From 25cf0d8aa2a3440ed32bf1f8df1310d6baf3f1e8 Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Thu, 6 May 2021 21:33:53 +0200
Subject: [PATCH 01/20] objtool: Rewrite hashtable sizing

Currently objtool has 5 hashtables and sizes them 16 or 20 bits
depending on the --vmlinux argument.

However, a single side doesn't really work well for the 5 tables,
which among them, cover 3 different uses. Also, while vmlinux is
larger, there is still a very wide difference between a defconfig and
allyesconfig build, which again isn't optimally covered by a single
size.

Another aspect is the cost of elf_hash_init(), which for large tables
dominates the runtime for small input files. It turns out that all it
does it assign NULL, something that is required when using malloc().
However, when we allocate memory using mmap(), we're guaranteed to get
zero filled pages.

Therefore, rewrite the whole thing to:

 1) use more dynamic sized tables, depending on the input file,
 2) avoid the need for elf_hash_init() entirely by using mmap().

This speeds up a regular kernel build (100s to 98s for
x86_64-defconfig), and potentially dramatically speeds up vmlinux
processing.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210506194157.452881700@infradead.org
---
 tools/objtool/elf.c                 | 113 +++++++++++++++++-----------
 tools/objtool/include/objtool/elf.h |  17 +++--
 2 files changed, 83 insertions(+), 47 deletions(-)

diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index d08f5f3670f8..a8a0ee21f71a 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -9,6 +9,7 @@
 
 #include <sys/types.h>
 #include <sys/stat.h>
+#include <sys/mman.h>
 #include <fcntl.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -27,21 +28,27 @@ static inline u32 str_hash(const char *str)
 	return jhash(str, strlen(str), 0);
 }
 
-static inline int elf_hash_bits(void)
-{
-	return vmlinux ? ELF_HASH_BITS : 16;
-}
+#define __elf_table(name)	(elf->name##_hash)
+#define __elf_bits(name)	(elf->name##_bits)
 
-#define elf_hash_add(hashtable, node, key) \
-	hlist_add_head(node, &hashtable[hash_min(key, elf_hash_bits())])
+#define elf_hash_add(name, node, key) \
+	hlist_add_head(node, &__elf_table(name)[hash_min(key, __elf_bits(name))])
 
-static void elf_hash_init(struct hlist_head *table)
-{
-	__hash_init(table, 1U << elf_hash_bits());
-}
+#define elf_hash_for_each_possible(name, obj, member, key) \
+	hlist_for_each_entry(obj, &__elf_table(name)[hash_min(key, __elf_bits(name))], member)
 
-#define elf_hash_for_each_possible(name, obj, member, key)			\
-	hlist_for_each_entry(obj, &name[hash_min(key, elf_hash_bits())], member)
+#define elf_alloc_hash(name, size) \
+({ \
+	__elf_bits(name) = max(10, ilog2(size)); \
+	__elf_table(name) = mmap(NULL, sizeof(struct hlist_head) << __elf_bits(name), \
+				 PROT_READ|PROT_WRITE, \
+				 MAP_PRIVATE|MAP_ANON, -1, 0); \
+	if (__elf_table(name) == (void *)-1L) { \
+		WARN("mmap fail " #name); \
+		__elf_table(name) = NULL; \
+	} \
+	__elf_table(name); \
+})
 
 static bool symbol_to_offset(struct rb_node *a, const struct rb_node *b)
 {
@@ -80,9 +87,10 @@ struct section *find_section_by_name(const struct elf *elf, const char *name)
 {
 	struct section *sec;
 
-	elf_hash_for_each_possible(elf->section_name_hash, sec, name_hash, str_hash(name))
+	elf_hash_for_each_possible(section_name, sec, name_hash, str_hash(name)) {
 		if (!strcmp(sec->name, name))
 			return sec;
+	}
 
 	return NULL;
 }
@@ -92,9 +100,10 @@ static struct section *find_section_by_index(struct elf *elf,
 {
 	struct section *sec;
 
-	elf_hash_for_each_possible(elf->section_hash, sec, hash, idx)
+	elf_hash_for_each_possible(section, sec, hash, idx) {
 		if (sec->idx == idx)
 			return sec;
+	}
 
 	return NULL;
 }
@@ -103,9 +112,10 @@ static struct symbol *find_symbol_by_index(struct elf *elf, unsigned int idx)
 {
 	struct symbol *sym;
 
-	elf_hash_for_each_possible(elf->symbol_hash, sym, hash, idx)
+	elf_hash_for_each_possible(symbol, sym, hash, idx) {
 		if (sym->idx == idx)
 			return sym;
+	}
 
 	return NULL;
 }
@@ -170,9 +180,10 @@ struct symbol *find_symbol_by_name(const struct elf *elf, const char *name)
 {
 	struct symbol *sym;
 
-	elf_hash_for_each_possible(elf->symbol_name_hash, sym, name_hash, str_hash(name))
+	elf_hash_for_each_possible(symbol_name, sym, name_hash, str_hash(name)) {
 		if (!strcmp(sym->name, name))
 			return sym;
+	}
 
 	return NULL;
 }
@@ -189,8 +200,8 @@ struct reloc *find_reloc_by_dest_range(const struct elf *elf, struct section *se
 	sec = sec->reloc;
 
 	for_offset_range(o, offset, offset + len) {
-		elf_hash_for_each_possible(elf->reloc_hash, reloc, hash,
-				       sec_offset_hash(sec, o)) {
+		elf_hash_for_each_possible(reloc, reloc, hash,
+					   sec_offset_hash(sec, o)) {
 			if (reloc->sec != sec)
 				continue;
 
@@ -228,6 +239,10 @@ static int read_sections(struct elf *elf)
 		return -1;
 	}
 
+	if (!elf_alloc_hash(section, sections_nr) ||
+	    !elf_alloc_hash(section_name, sections_nr))
+		return -1;
+
 	for (i = 0; i < sections_nr; i++) {
 		sec = malloc(sizeof(*sec));
 		if (!sec) {
@@ -274,12 +289,14 @@ static int read_sections(struct elf *elf)
 		sec->len = sec->sh.sh_size;
 
 		list_add_tail(&sec->list, &elf->sections);
-		elf_hash_add(elf->section_hash, &sec->hash, sec->idx);
-		elf_hash_add(elf->section_name_hash, &sec->name_hash, str_hash(sec->name));
+		elf_hash_add(section, &sec->hash, sec->idx);
+		elf_hash_add(section_name, &sec->name_hash, str_hash(sec->name));
 	}
 
-	if (stats)
+	if (stats) {
 		printf("nr_sections: %lu\n", (unsigned long)sections_nr);
+		printf("section_bits: %d\n", elf->section_bits);
+	}
 
 	/* sanity check, one more call to elf_nextscn() should return NULL */
 	if (elf_nextscn(elf->elf, s)) {
@@ -308,8 +325,8 @@ static void elf_add_symbol(struct elf *elf, struct symbol *sym)
 	else
 		entry = &sym->sec->symbol_list;
 	list_add(&sym->list, entry);
-	elf_hash_add(elf->symbol_hash, &sym->hash, sym->idx);
-	elf_hash_add(elf->symbol_name_hash, &sym->name_hash, str_hash(sym->name));
+	elf_hash_add(symbol, &sym->hash, sym->idx);
+	elf_hash_add(symbol_name, &sym->name_hash, str_hash(sym->name));
 
 	/*
 	 * Don't store empty STT_NOTYPE symbols in the rbtree.  They
@@ -329,19 +346,25 @@ static int read_symbols(struct elf *elf)
 	Elf32_Word shndx;
 
 	symtab = find_section_by_name(elf, ".symtab");
-	if (!symtab) {
+	if (symtab) {
+		symtab_shndx = find_section_by_name(elf, ".symtab_shndx");
+		if (symtab_shndx)
+			shndx_data = symtab_shndx->data;
+
+		symbols_nr = symtab->sh.sh_size / symtab->sh.sh_entsize;
+	} else {
 		/*
 		 * A missing symbol table is actually possible if it's an empty
-		 * .o file.  This can happen for thunk_64.o.
+		 * .o file. This can happen for thunk_64.o. Make sure to at
+		 * least allocate the symbol hash tables so we can do symbol
+		 * lookups without crashing.
 		 */
-		return 0;
+		symbols_nr = 0;
 	}
 
-	symtab_shndx = find_section_by_name(elf, ".symtab_shndx");
-	if (symtab_shndx)
-		shndx_data = symtab_shndx->data;
-
-	symbols_nr = symtab->sh.sh_size / symtab->sh.sh_entsize;
+	if (!elf_alloc_hash(symbol, symbols_nr) ||
+	    !elf_alloc_hash(symbol_name, symbols_nr))
+		return -1;
 
 	for (i = 0; i < symbols_nr; i++) {
 		sym = malloc(sizeof(*sym));
@@ -389,8 +412,10 @@ static int read_symbols(struct elf *elf)
 		elf_add_symbol(elf, sym);
 	}
 
-	if (stats)
+	if (stats) {
 		printf("nr_symbols: %lu\n", (unsigned long)symbols_nr);
+		printf("symbol_bits: %d\n", elf->symbol_bits);
+	}
 
 	/* Create parent/child links for any cold subfunctions */
 	list_for_each_entry(sec, &elf->sections, list) {
@@ -479,7 +504,7 @@ int elf_add_reloc(struct elf *elf, struct section *sec, unsigned long offset,
 	reloc->addend = addend;
 
 	list_add_tail(&reloc->list, &sec->reloc->reloc_list);
-	elf_hash_add(elf->reloc_hash, &reloc->hash, reloc_hash(reloc));
+	elf_hash_add(reloc, &reloc->hash, reloc_hash(reloc));
 
 	sec->reloc->changed = true;
 
@@ -556,6 +581,15 @@ static int read_relocs(struct elf *elf)
 	unsigned int symndx;
 	unsigned long nr_reloc, max_reloc = 0, tot_reloc = 0;
 
+	sec = find_section_by_name(elf, ".text");
+	if (!sec) {
+		WARN("no .text");
+		return -1;
+	}
+
+	if (!elf_alloc_hash(reloc, sec->len / 16))
+		return -1;
+
 	list_for_each_entry(sec, &elf->sections, list) {
 		if ((sec->sh.sh_type != SHT_RELA) &&
 		    (sec->sh.sh_type != SHT_REL))
@@ -600,7 +634,7 @@ static int read_relocs(struct elf *elf)
 			}
 
 			list_add_tail(&reloc->list, &sec->reloc_list);
-			elf_hash_add(elf->reloc_hash, &reloc->hash, reloc_hash(reloc));
+			elf_hash_add(reloc, &reloc->hash, reloc_hash(reloc));
 
 			nr_reloc++;
 		}
@@ -611,6 +645,7 @@ static int read_relocs(struct elf *elf)
 	if (stats) {
 		printf("max_reloc: %lu\n", max_reloc);
 		printf("tot_reloc: %lu\n", tot_reloc);
+		printf("reloc_bits: %d\n", elf->reloc_bits);
 	}
 
 	return 0;
@@ -632,12 +667,6 @@ struct elf *elf_open_read(const char *name, int flags)
 
 	INIT_LIST_HEAD(&elf->sections);
 
-	elf_hash_init(elf->symbol_hash);
-	elf_hash_init(elf->symbol_name_hash);
-	elf_hash_init(elf->section_hash);
-	elf_hash_init(elf->section_name_hash);
-	elf_hash_init(elf->reloc_hash);
-
 	elf->fd = open(name, flags);
 	if (elf->fd == -1) {
 		fprintf(stderr, "objtool: Can't open '%s': %s\n",
@@ -850,8 +879,8 @@ struct section *elf_create_section(struct elf *elf, const char *name,
 		return NULL;
 
 	list_add_tail(&sec->list, &elf->sections);
-	elf_hash_add(elf->section_hash, &sec->hash, sec->idx);
-	elf_hash_add(elf->section_name_hash, &sec->name_hash, str_hash(sec->name));
+	elf_hash_add(section, &sec->hash, sec->idx);
+	elf_hash_add(section_name, &sec->name_hash, str_hash(sec->name));
 
 	elf->changed = true;
 
diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h
index 45e5ede363b0..90082751f851 100644
--- a/tools/objtool/include/objtool/elf.h
+++ b/tools/objtool/include/objtool/elf.h
@@ -84,11 +84,18 @@ struct elf {
 	bool changed;
 	char *name;
 	struct list_head sections;
-	DECLARE_HASHTABLE(symbol_hash, ELF_HASH_BITS);
-	DECLARE_HASHTABLE(symbol_name_hash, ELF_HASH_BITS);
-	DECLARE_HASHTABLE(section_hash, ELF_HASH_BITS);
-	DECLARE_HASHTABLE(section_name_hash, ELF_HASH_BITS);
-	DECLARE_HASHTABLE(reloc_hash, ELF_HASH_BITS);
+
+	int symbol_bits;
+	int symbol_name_bits;
+	int section_bits;
+	int section_name_bits;
+	int reloc_bits;
+
+	struct hlist_head *symbol_hash;
+	struct hlist_head *symbol_name_hash;
+	struct hlist_head *section_hash;
+	struct hlist_head *section_name_hash;
+	struct hlist_head *reloc_hash;
 };
 
 #define OFFSET_STRIDE_BITS	4

From 80870e6ece78ce67b91398db88fb6b92a178f574 Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Thu, 6 May 2021 21:33:54 +0200
Subject: [PATCH 02/20] x86, objtool: Dont exclude arch/x86/realmode/

Specifically, init.c uses jump_labels.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210506194157.516200011@infradead.org
---
 arch/x86/realmode/Makefile | 1 -
 1 file changed, 1 deletion(-)

diff --git a/arch/x86/realmode/Makefile b/arch/x86/realmode/Makefile
index 6b1f3a4eeb44..a0b491ae2de8 100644
--- a/arch/x86/realmode/Makefile
+++ b/arch/x86/realmode/Makefile
@@ -10,7 +10,6 @@
 # Sanitizer runtimes are unavailable and cannot be linked here.
 KASAN_SANITIZE			:= n
 KCSAN_SANITIZE			:= n
-OBJECT_FILES_NON_STANDARD	:= y
 
 subdir- := rm
 

From 8bfafcdccb52e770695b12530b1f800fe98b16b1 Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Thu, 6 May 2021 21:33:55 +0200
Subject: [PATCH 03/20] jump_label, x86: Strip ASM jump_label support

In prepration for variable size jump_label support; remove all ASM
bits, which are currently unused.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210506194157.599716762@infradead.org
---
 arch/x86/include/asm/jump_label.h | 36 -------------------------------
 1 file changed, 36 deletions(-)

diff --git a/arch/x86/include/asm/jump_label.h b/arch/x86/include/asm/jump_label.h
index 610a05374c02..01de21e2d967 100644
--- a/arch/x86/include/asm/jump_label.h
+++ b/arch/x86/include/asm/jump_label.h
@@ -47,42 +47,6 @@ static __always_inline bool arch_static_branch_jump(struct static_key * const ke
 	return true;
 }
 
-#else	/* __ASSEMBLY__ */
-
-.macro STATIC_JUMP_IF_TRUE target, key, def
-.Lstatic_jump_\@:
-	.if \def
-	/* Equivalent to "jmp.d32 \target" */
-	.byte		0xe9
-	.long		\target - .Lstatic_jump_after_\@
-.Lstatic_jump_after_\@:
-	.else
-	.byte		BYTES_NOP5
-	.endif
-	.pushsection __jump_table, "aw"
-	_ASM_ALIGN
-	.long		.Lstatic_jump_\@ - ., \target - .
-	_ASM_PTR	\key - .
-	.popsection
-.endm
-
-.macro STATIC_JUMP_IF_FALSE target, key, def
-.Lstatic_jump_\@:
-	.if \def
-	.byte		BYTES_NOP5
-	.else
-	/* Equivalent to "jmp.d32 \target" */
-	.byte		0xe9
-	.long		\target - .Lstatic_jump_after_\@
-.Lstatic_jump_after_\@:
-	.endif
-	.pushsection __jump_table, "aw"
-	_ASM_ALIGN
-	.long		.Lstatic_jump_\@ - ., \target - .
-	_ASM_PTR	\key + 1 - .
-	.popsection
-.endm
-
 #endif	/* __ASSEMBLY__ */
 
 #endif

From e1aa35c4c4bc71e44dabc9d7d167b807edd7b439 Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Thu, 6 May 2021 21:33:56 +0200
Subject: [PATCH 04/20] jump_label, x86: Factor out the __jump_table generation

Both arch_static_branch() and arch_static_branch_jump() have the same
blurb to generate the __jump_table entry, share it.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210506194157.663132781@infradead.org
---
 arch/x86/include/asm/jump_label.h | 24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/arch/x86/include/asm/jump_label.h b/arch/x86/include/asm/jump_label.h
index 01de21e2d967..dfdc2b1c17dd 100644
--- a/arch/x86/include/asm/jump_label.h
+++ b/arch/x86/include/asm/jump_label.h
@@ -14,15 +14,19 @@
 #include <linux/stringify.h>
 #include <linux/types.h>
 
+#define JUMP_TABLE_ENTRY				\
+	".pushsection __jump_table,  \"aw\" \n\t"	\
+	_ASM_ALIGN "\n\t"				\
+	".long 1b - . \n\t"				\
+	".long %l[l_yes] - . \n\t"			\
+	_ASM_PTR "%c0 + %c1 - .\n\t"			\
+	".popsection \n\t"
+
 static __always_inline bool arch_static_branch(struct static_key * const key, const bool branch)
 {
 	asm_volatile_goto("1:"
 		".byte " __stringify(BYTES_NOP5) "\n\t"
-		".pushsection __jump_table,  \"aw\" \n\t"
-		_ASM_ALIGN "\n\t"
-		".long 1b - ., %l[l_yes] - . \n\t"
-		_ASM_PTR "%c0 + %c1 - .\n\t"
-		".popsection \n\t"
+		JUMP_TABLE_ENTRY
 		: :  "i" (key), "i" (branch) : : l_yes);
 
 	return false;
@@ -33,13 +37,9 @@ static __always_inline bool arch_static_branch(struct static_key * const key, co
 static __always_inline bool arch_static_branch_jump(struct static_key * const key, const bool branch)
 {
 	asm_volatile_goto("1:"
-		".byte 0xe9\n\t .long %l[l_yes] - 2f\n\t"
-		"2:\n\t"
-		".pushsection __jump_table,  \"aw\" \n\t"
-		_ASM_ALIGN "\n\t"
-		".long 1b - ., %l[l_yes] - . \n\t"
-		_ASM_PTR "%c0 + %c1 - .\n\t"
-		".popsection \n\t"
+		".byte 0xe9 \n\t"
+		".long %l[l_yes] - (. + 4) \n\t"
+		JUMP_TABLE_ENTRY
 		: :  "i" (key), "i" (branch) : : l_yes);
 
 	return false;

From f9510fa9caaf8229381d5f86ba0774bf1a6ca39b Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Thu, 6 May 2021 21:33:57 +0200
Subject: [PATCH 05/20] jump_label, x86: Improve error when we fail expected
 text

There is only a single usage site left, remove the function and extend
the print to include more information, like the expected text and the
patch type.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210506194157.726939027@infradead.org
---
 arch/x86/kernel/jump_label.c | 33 ++++++++++++++-------------------
 1 file changed, 14 insertions(+), 19 deletions(-)

diff --git a/arch/x86/kernel/jump_label.c b/arch/x86/kernel/jump_label.c
index 6a2eb62c85e6..638d3b9be0ad 100644
--- a/arch/x86/kernel/jump_label.c
+++ b/arch/x86/kernel/jump_label.c
@@ -16,37 +16,32 @@
 #include <asm/alternative.h>
 #include <asm/text-patching.h>
 
-static void bug_at(const void *ip, int line)
-{
-	/*
-	 * The location is not an op that we were expecting.
-	 * Something went wrong. Crash the box, as something could be
-	 * corrupting the kernel.
-	 */
-	pr_crit("jump_label: Fatal kernel bug, unexpected op at %pS [%p] (%5ph) %d\n", ip, ip, ip, line);
-	BUG();
-}
-
 static const void *
 __jump_label_set_jump_code(struct jump_entry *entry, enum jump_label_type type)
 {
 	const void *expect, *code;
 	const void *addr, *dest;
-	int line;
 
 	addr = (void *)jump_entry_code(entry);
 	dest = (void *)jump_entry_target(entry);
 
 	code = text_gen_insn(JMP32_INSN_OPCODE, addr, dest);
 
-	if (type == JUMP_LABEL_JMP) {
-		expect = x86_nops[5]; line = __LINE__;
-	} else {
-		expect = code; line = __LINE__;
-	}
+	if (type == JUMP_LABEL_JMP)
+		expect = x86_nops[5];
+	else
+		expect = code;
 
-	if (memcmp(addr, expect, JUMP_LABEL_NOP_SIZE))
-		bug_at(addr, line);
+	if (memcmp(addr, expect, JUMP_LABEL_NOP_SIZE)) {
+		/*
+		 * The location is not an op that we were expecting.
+		 * Something went wrong. Crash the box, as something could be
+		 * corrupting the kernel.
+		 */
+		pr_crit("jump_label: Fatal kernel bug, unexpected op at %pS [%p] (%5ph != %5ph)) type:%d\n",
+				addr, addr, addr, expect, type);
+		BUG();
+	}
 
 	if (type == JUMP_LABEL_NOP)
 		code = x86_nops[5];

From fa5e5dc39669b4427830c546ede8709323b8276c Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Thu, 6 May 2021 21:33:58 +0200
Subject: [PATCH 06/20] jump_label, x86: Introduce jump_entry_size()

This allows architectures to have variable sized jumps.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210506194157.786777050@infradead.org
---
 arch/x86/include/asm/jump_label.h | 4 ++--
 arch/x86/kernel/jump_label.c      | 7 +++++++
 include/linux/jump_label.h        | 9 +++++++++
 kernel/jump_label.c               | 2 +-
 4 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/arch/x86/include/asm/jump_label.h b/arch/x86/include/asm/jump_label.h
index dfdc2b1c17dd..d85802a00629 100644
--- a/arch/x86/include/asm/jump_label.h
+++ b/arch/x86/include/asm/jump_label.h
@@ -4,8 +4,6 @@
 
 #define HAVE_JUMP_LABEL_BATCH
 
-#define JUMP_LABEL_NOP_SIZE 5
-
 #include <asm/asm.h>
 #include <asm/nops.h>
 
@@ -47,6 +45,8 @@ static __always_inline bool arch_static_branch_jump(struct static_key * const ke
 	return true;
 }
 
+extern int arch_jump_entry_size(struct jump_entry *entry);
+
 #endif	/* __ASSEMBLY__ */
 
 #endif
diff --git a/arch/x86/kernel/jump_label.c b/arch/x86/kernel/jump_label.c
index 638d3b9be0ad..a29eecc14c94 100644
--- a/arch/x86/kernel/jump_label.c
+++ b/arch/x86/kernel/jump_label.c
@@ -16,6 +16,13 @@
 #include <asm/alternative.h>
 #include <asm/text-patching.h>
 
+#define JUMP_LABEL_NOP_SIZE	JMP32_INSN_SIZE
+
+int arch_jump_entry_size(struct jump_entry *entry)
+{
+	return JMP32_INSN_SIZE;
+}
+
 static const void *
 __jump_label_set_jump_code(struct jump_entry *entry, enum jump_label_type type)
 {
diff --git a/include/linux/jump_label.h b/include/linux/jump_label.h
index 05f5554d860f..8c45f58292ac 100644
--- a/include/linux/jump_label.h
+++ b/include/linux/jump_label.h
@@ -176,6 +176,15 @@ static inline void jump_entry_set_init(struct jump_entry *entry)
 	entry->key |= 2;
 }
 
+static inline int jump_entry_size(struct jump_entry *entry)
+{
+#ifdef JUMP_LABEL_NOP_SIZE
+	return JUMP_LABEL_NOP_SIZE;
+#else
+	return arch_jump_entry_size(entry);
+#endif
+}
+
 #endif
 #endif
 
diff --git a/kernel/jump_label.c b/kernel/jump_label.c
index ba39fbb1f8e7..521cafcfcb69 100644
--- a/kernel/jump_label.c
+++ b/kernel/jump_label.c
@@ -309,7 +309,7 @@ EXPORT_SYMBOL_GPL(jump_label_rate_limit);
 static int addr_conflict(struct jump_entry *entry, void *start, void *end)
 {
 	if (jump_entry_code(entry) <= (unsigned long)end &&
-	    jump_entry_code(entry) + JUMP_LABEL_NOP_SIZE > (unsigned long)start)
+	    jump_entry_code(entry) + jump_entry_size(entry) > (unsigned long)start)
 		return 1;
 
 	return 0;

From 001951bea748d3f675e1778f42b17290a8c551bf Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Thu, 6 May 2021 21:33:59 +0200
Subject: [PATCH 07/20] jump_label, x86: Add variable length patching support

This allows the patching to to emit 2 byte JMP/NOP instruction in
addition to the 5 byte JMP/NOP we already did. This allows for more
compact code.

This code is not yet used, as we don't emit shorter code at compile
time yet.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210506194157.846870383@infradead.org
---
 arch/x86/kernel/jump_label.c | 53 ++++++++++++++++++++++++------------
 1 file changed, 35 insertions(+), 18 deletions(-)

diff --git a/arch/x86/kernel/jump_label.c b/arch/x86/kernel/jump_label.c
index a29eecc14c94..190d810fa435 100644
--- a/arch/x86/kernel/jump_label.c
+++ b/arch/x86/kernel/jump_label.c
@@ -23,44 +23,63 @@ int arch_jump_entry_size(struct jump_entry *entry)
 	return JMP32_INSN_SIZE;
 }
 
-static const void *
-__jump_label_set_jump_code(struct jump_entry *entry, enum jump_label_type type)
+struct jump_label_patch {
+	const void *code;
+	int size;
+};
+
+static struct jump_label_patch
+__jump_label_patch(struct jump_entry *entry, enum jump_label_type type)
 {
-	const void *expect, *code;
+	const void *expect, *code, *nop;
 	const void *addr, *dest;
+	int size;
 
 	addr = (void *)jump_entry_code(entry);
 	dest = (void *)jump_entry_target(entry);
 
-	code = text_gen_insn(JMP32_INSN_OPCODE, addr, dest);
+	size = arch_jump_entry_size(entry);
+	switch (size) {
+	case JMP8_INSN_SIZE:
+		code = text_gen_insn(JMP8_INSN_OPCODE, addr, dest);
+		nop = x86_nops[size];
+		break;
+
+	case JMP32_INSN_SIZE:
+		code = text_gen_insn(JMP32_INSN_OPCODE, addr, dest);
+		nop = x86_nops[size];
+		break;
+
+	default: BUG();
+	}
 
 	if (type == JUMP_LABEL_JMP)
-		expect = x86_nops[5];
+		expect = nop;
 	else
 		expect = code;
 
-	if (memcmp(addr, expect, JUMP_LABEL_NOP_SIZE)) {
+	if (memcmp(addr, expect, size)) {
 		/*
 		 * The location is not an op that we were expecting.
 		 * Something went wrong. Crash the box, as something could be
 		 * corrupting the kernel.
 		 */
-		pr_crit("jump_label: Fatal kernel bug, unexpected op at %pS [%p] (%5ph != %5ph)) type:%d\n",
-				addr, addr, addr, expect, type);
+		pr_crit("jump_label: Fatal kernel bug, unexpected op at %pS [%p] (%5ph != %5ph)) size:%d type:%d\n",
+				addr, addr, addr, expect, size, type);
 		BUG();
 	}
 
 	if (type == JUMP_LABEL_NOP)
-		code = x86_nops[5];
+		code = nop;
 
-	return code;
+	return (struct jump_label_patch){.code = code, .size = size};
 }
 
 static inline void __jump_label_transform(struct jump_entry *entry,
 					  enum jump_label_type type,
 					  int init)
 {
-	const void *opcode = __jump_label_set_jump_code(entry, type);
+	const struct jump_label_patch jlp = __jump_label_patch(entry, type);
 
 	/*
 	 * As long as only a single processor is running and the code is still
@@ -74,12 +93,11 @@ static inline void __jump_label_transform(struct jump_entry *entry,
 	 * always nop being the 'currently valid' instruction
 	 */
 	if (init || system_state == SYSTEM_BOOTING) {
-		text_poke_early((void *)jump_entry_code(entry), opcode,
-				JUMP_LABEL_NOP_SIZE);
+		text_poke_early((void *)jump_entry_code(entry), jlp.code, jlp.size);
 		return;
 	}
 
-	text_poke_bp((void *)jump_entry_code(entry), opcode, JUMP_LABEL_NOP_SIZE, NULL);
+	text_poke_bp((void *)jump_entry_code(entry), jlp.code, jlp.size, NULL);
 }
 
 static void __ref jump_label_transform(struct jump_entry *entry,
@@ -100,7 +118,7 @@ void arch_jump_label_transform(struct jump_entry *entry,
 bool arch_jump_label_transform_queue(struct jump_entry *entry,
 				     enum jump_label_type type)
 {
-	const void *opcode;
+	struct jump_label_patch jlp;
 
 	if (system_state == SYSTEM_BOOTING) {
 		/*
@@ -111,9 +129,8 @@ bool arch_jump_label_transform_queue(struct jump_entry *entry,
 	}
 
 	mutex_lock(&text_mutex);
-	opcode = __jump_label_set_jump_code(entry, type);
-	text_poke_queue((void *)jump_entry_code(entry),
-			opcode, JUMP_LABEL_NOP_SIZE, NULL);
+	jlp = __jump_label_patch(entry, type);
+	text_poke_queue((void *)jump_entry_code(entry), jlp.code, jlp.size, NULL);
 	mutex_unlock(&text_mutex);
 	return true;
 }

From 5af0ea293d78c8b8f0b87ae2b13f7ac584057bc3 Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Thu, 6 May 2021 21:34:00 +0200
Subject: [PATCH 08/20] jump_label: Free jump_entry::key bit1 for build use

Have jump_label_init() set jump_entry::key bit1 to either 0 ot 1
unconditionally. This makes it available for build-time games.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210506194157.906893264@infradead.org
---
 include/linux/jump_label.h |  7 +++++--
 kernel/jump_label.c        | 10 ++++++----
 2 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/include/linux/jump_label.h b/include/linux/jump_label.h
index 8c45f58292ac..48b9b2a82767 100644
--- a/include/linux/jump_label.h
+++ b/include/linux/jump_label.h
@@ -171,9 +171,12 @@ static inline bool jump_entry_is_init(const struct jump_entry *entry)
 	return (unsigned long)entry->key & 2UL;
 }
 
-static inline void jump_entry_set_init(struct jump_entry *entry)
+static inline void jump_entry_set_init(struct jump_entry *entry, bool set)
 {
-	entry->key |= 2;
+	if (set)
+		entry->key |= 2;
+	else
+		entry->key &= ~2;
 }
 
 static inline int jump_entry_size(struct jump_entry *entry)
diff --git a/kernel/jump_label.c b/kernel/jump_label.c
index 521cafcfcb69..bdb0681bece8 100644
--- a/kernel/jump_label.c
+++ b/kernel/jump_label.c
@@ -483,13 +483,14 @@ void __init jump_label_init(void)
 
 	for (iter = iter_start; iter < iter_stop; iter++) {
 		struct static_key *iterk;
+		bool in_init;
 
 		/* rewrite NOPs */
 		if (jump_label_type(iter) == JUMP_LABEL_NOP)
 			arch_jump_label_transform_static(iter, JUMP_LABEL_NOP);
 
-		if (init_section_contains((void *)jump_entry_code(iter), 1))
-			jump_entry_set_init(iter);
+		in_init = init_section_contains((void *)jump_entry_code(iter), 1);
+		jump_entry_set_init(iter, in_init);
 
 		iterk = jump_entry_key(iter);
 		if (iterk == key)
@@ -634,9 +635,10 @@ static int jump_label_add_module(struct module *mod)
 
 	for (iter = iter_start; iter < iter_stop; iter++) {
 		struct static_key *iterk;
+		bool in_init;
 
-		if (within_module_init(jump_entry_code(iter), mod))
-			jump_entry_set_init(iter);
+		in_init = within_module_init(jump_entry_code(iter), mod);
+		jump_entry_set_init(iter, in_init);
 
 		iterk = jump_entry_key(iter);
 		if (iterk == key)

From e7bf1ba97afdde75b0ef43e4bdb718bf843613f1 Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Thu, 6 May 2021 21:34:01 +0200
Subject: [PATCH 09/20] jump_label, x86: Emit short JMP

Now that we can patch short JMP/NOP, allow the compiler/assembler to
emit short JMP instructions.

There is no way to have the assembler emit short NOPs based on the
potential displacement, so leave those long for now.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210506194157.967034497@infradead.org
---
 arch/x86/include/asm/jump_label.h | 3 +--
 arch/x86/kernel/jump_label.c      | 8 +++++++-
 2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/arch/x86/include/asm/jump_label.h b/arch/x86/include/asm/jump_label.h
index d85802a00629..ef819e33cfc1 100644
--- a/arch/x86/include/asm/jump_label.h
+++ b/arch/x86/include/asm/jump_label.h
@@ -35,8 +35,7 @@ static __always_inline bool arch_static_branch(struct static_key * const key, co
 static __always_inline bool arch_static_branch_jump(struct static_key * const key, const bool branch)
 {
 	asm_volatile_goto("1:"
-		".byte 0xe9 \n\t"
-		".long %l[l_yes] - (. + 4) \n\t"
+		"jmp %l[l_yes]\n\t"
 		JUMP_TABLE_ENTRY
 		: :  "i" (key), "i" (branch) : : l_yes);
 
diff --git a/arch/x86/kernel/jump_label.c b/arch/x86/kernel/jump_label.c
index 190d810fa435..a762dc1c615e 100644
--- a/arch/x86/kernel/jump_label.c
+++ b/arch/x86/kernel/jump_label.c
@@ -15,12 +15,18 @@
 #include <asm/kprobes.h>
 #include <asm/alternative.h>
 #include <asm/text-patching.h>
+#include <asm/insn.h>
 
 #define JUMP_LABEL_NOP_SIZE	JMP32_INSN_SIZE
 
 int arch_jump_entry_size(struct jump_entry *entry)
 {
-	return JMP32_INSN_SIZE;
+	struct insn insn = {};
+
+	insn_decode_kernel(&insn, (void *)jump_entry_code(entry));
+	BUG_ON(insn.length != 2 && insn.length != 5);
+
+	return insn.length;
 }
 
 struct jump_label_patch {

From cbf82a3dc241aea82b941a872ed5c52f6af527ea Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Thu, 6 May 2021 21:34:02 +0200
Subject: [PATCH 10/20] objtool: Decode jump_entry::key addend

Teach objtool about the the low bits in the struct static_key pointer.

That is, the low two bits of @key in:

  struct jump_entry {
	s32 code;
	s32 target;
	long key;
  }

as found in the __jump_table section. Since @key has a relocation to
the variable (to be resolved by the linker), the low two bits will be
reflected in the relocation's addend.

As such, find the reloc and store the addend, such that we can access
these bits.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210506194158.028024143@infradead.org
---
 tools/objtool/arch/x86/include/arch/special.h |  1 +
 tools/objtool/include/objtool/special.h       |  1 +
 tools/objtool/special.c                       | 14 ++++++++++++++
 3 files changed, 16 insertions(+)

diff --git a/tools/objtool/arch/x86/include/arch/special.h b/tools/objtool/arch/x86/include/arch/special.h
index 14271cca0c74..f2918f789a0a 100644
--- a/tools/objtool/arch/x86/include/arch/special.h
+++ b/tools/objtool/arch/x86/include/arch/special.h
@@ -9,6 +9,7 @@
 #define JUMP_ENTRY_SIZE		16
 #define JUMP_ORIG_OFFSET	0
 #define JUMP_NEW_OFFSET		4
+#define JUMP_KEY_OFFSET		8
 
 #define ALT_ENTRY_SIZE		12
 #define ALT_ORIG_OFFSET		0
diff --git a/tools/objtool/include/objtool/special.h b/tools/objtool/include/objtool/special.h
index 8a09f4e9d480..dc4721e19002 100644
--- a/tools/objtool/include/objtool/special.h
+++ b/tools/objtool/include/objtool/special.h
@@ -27,6 +27,7 @@ struct special_alt {
 	unsigned long new_off;
 
 	unsigned int orig_len, new_len; /* group only */
+	u8 key_addend;
 };
 
 int special_get_alts(struct elf *elf, struct list_head *alts);
diff --git a/tools/objtool/special.c b/tools/objtool/special.c
index 07b21cfabf5c..bc925cf19e2d 100644
--- a/tools/objtool/special.c
+++ b/tools/objtool/special.c
@@ -23,6 +23,7 @@ struct special_entry {
 	unsigned char size, orig, new;
 	unsigned char orig_len, new_len; /* group only */
 	unsigned char feature; /* ALTERNATIVE macro CPU feature */
+	unsigned char key; /* jump_label key */
 };
 
 struct special_entry entries[] = {
@@ -42,6 +43,7 @@ struct special_entry entries[] = {
 		.size = JUMP_ENTRY_SIZE,
 		.orig = JUMP_ORIG_OFFSET,
 		.new = JUMP_NEW_OFFSET,
+		.key = JUMP_KEY_OFFSET,
 	},
 	{
 		.sec = "__ex_table",
@@ -122,6 +124,18 @@ static int get_alt_entry(struct elf *elf, struct special_entry *entry,
 			alt->new_off -= 0x7ffffff0;
 	}
 
+	if (entry->key) {
+		struct reloc *key_reloc;
+
+		key_reloc = find_reloc_by_dest(elf, sec, offset + entry->key);
+		if (!key_reloc) {
+			WARN_FUNC("can't find key reloc",
+				  sec, offset + entry->key);
+			return -1;
+		}
+		alt->key_addend = key_reloc->addend;
+	}
+
 	return 0;
 }
 

From 6d37b83c5d79ef5996cc49c3e3ac3d8ecd8c7050 Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Thu, 6 May 2021 21:34:03 +0200
Subject: [PATCH 11/20] objtool: Rewrite jump_label instructions

When a jump_entry::key has bit1 set, rewrite the instruction to be a
NOP. This allows the compiler/assembler to emit JMP (and thus decide
on which encoding to use).

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210506194158.091028792@infradead.org
---
 tools/objtool/check.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 9ed1a4cd00dc..98cf87f2c501 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -1234,6 +1234,20 @@ static int handle_jump_alt(struct objtool_file *file,
 		return -1;
 	}
 
+	if (special_alt->key_addend & 2) {
+		struct reloc *reloc = insn_reloc(file, orig_insn);
+
+		if (reloc) {
+			reloc->type = R_NONE;
+			elf_write_reloc(file->elf, reloc);
+		}
+		elf_write_insn(file->elf, orig_insn->sec,
+			       orig_insn->offset, orig_insn->len,
+			       arch_nop_insn(orig_insn->len));
+		orig_insn->type = INSN_NOP;
+		return 0;
+	}
+
 	*new_insn = list_next_entry(orig_insn, list);
 	return 0;
 }

From e2d9494beff21a26438eb611c260b8a6c2dc4dbf Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Thu, 6 May 2021 21:34:04 +0200
Subject: [PATCH 12/20] objtool: Provide stats for jump_labels

Add objtool --stats to count the jump_label sites it encounters.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210506194158.153101906@infradead.org
---
 tools/objtool/check.c                   | 22 ++++++++++++++++++++--
 tools/objtool/include/objtool/objtool.h |  3 +++
 2 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 98cf87f2c501..2c6a93edf27e 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -1225,8 +1225,15 @@ static int handle_jump_alt(struct objtool_file *file,
 			   struct instruction *orig_insn,
 			   struct instruction **new_insn)
 {
-	if (orig_insn->type == INSN_NOP)
+	if (orig_insn->type == INSN_NOP) {
+do_nop:
+		if (orig_insn->len == 2)
+			file->jl_nop_short++;
+		else
+			file->jl_nop_long++;
+
 		return 0;
+	}
 
 	if (orig_insn->type != INSN_JUMP_UNCONDITIONAL) {
 		WARN_FUNC("unsupported instruction at jump label",
@@ -1245,9 +1252,14 @@ static int handle_jump_alt(struct objtool_file *file,
 			       orig_insn->offset, orig_insn->len,
 			       arch_nop_insn(orig_insn->len));
 		orig_insn->type = INSN_NOP;
-		return 0;
+		goto do_nop;
 	}
 
+	if (orig_insn->len == 2)
+		file->jl_short++;
+	else
+		file->jl_long++;
+
 	*new_insn = list_next_entry(orig_insn, list);
 	return 0;
 }
@@ -1328,6 +1340,12 @@ static int add_special_section_alts(struct objtool_file *file)
 		free(special_alt);
 	}
 
+	if (stats) {
+		printf("jl\\\tNOP\tJMP\n");
+		printf("short:\t%ld\t%ld\n", file->jl_nop_short, file->jl_short);
+		printf("long:\t%ld\t%ld\n", file->jl_nop_long, file->jl_long);
+	}
+
 out:
 	return ret;
 }
diff --git a/tools/objtool/include/objtool/objtool.h b/tools/objtool/include/objtool/objtool.h
index e4084afb2304..24fa83634de4 100644
--- a/tools/objtool/include/objtool/objtool.h
+++ b/tools/objtool/include/objtool/objtool.h
@@ -22,6 +22,9 @@ struct objtool_file {
 	struct list_head static_call_list;
 	struct list_head mcount_loc_list;
 	bool ignore_unreachables, c_file, hints, rodata;
+
+	unsigned long jl_short, jl_long;
+	unsigned long jl_nop_short, jl_nop_long;
 };
 
 struct objtool_file *objtool_open_read(const char *_objname);

From ab3257042c26d0cd44793c741e2f89bf38b21fe8 Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Thu, 6 May 2021 21:34:05 +0200
Subject: [PATCH 13/20] jump_label, x86: Allow short NOPs

Now that objtool is able to rewrite jump_label instructions, have the
compiler emit a JMP, such that it can decide on the optimal encoding,
and set jump_entry::key bit1 to indicate that objtool should rewrite
the instruction to a matching NOP.

For x86_64-allyesconfig this gives:

  jl\     NOP     JMP
  short:  22997   124
  long:   30874   90

IOW, we save (22997+124) * 3 bytes of kernel text in hotpaths.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210506194158.216763632@infradead.org
---
 arch/x86/include/asm/jump_label.h | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/arch/x86/include/asm/jump_label.h b/arch/x86/include/asm/jump_label.h
index ef819e33cfc1..0449b125d27f 100644
--- a/arch/x86/include/asm/jump_label.h
+++ b/arch/x86/include/asm/jump_label.h
@@ -20,6 +20,22 @@
 	_ASM_PTR "%c0 + %c1 - .\n\t"			\
 	".popsection \n\t"
 
+#ifdef CONFIG_STACK_VALIDATION
+
+static __always_inline bool arch_static_branch(struct static_key *key, bool branch)
+{
+	asm_volatile_goto("1:"
+		"jmp %l[l_yes] # objtool NOPs this \n\t"
+		JUMP_TABLE_ENTRY
+		: :  "i" (key), "i" (2 | branch) : : l_yes);
+
+	return false;
+l_yes:
+	return true;
+}
+
+#else
+
 static __always_inline bool arch_static_branch(struct static_key * const key, const bool branch)
 {
 	asm_volatile_goto("1:"
@@ -32,6 +48,8 @@ static __always_inline bool arch_static_branch(struct static_key * const key, co
 	return true;
 }
 
+#endif /* STACK_VALIDATION */
+
 static __always_inline bool arch_static_branch_jump(struct static_key * const key, const bool branch)
 {
 	asm_volatile_goto("1:"

From d46f61b20b060f03b58fde170ee618f17dc6f99d Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Thu, 13 May 2021 16:16:47 +0200
Subject: [PATCH 14/20] jump_label/x86: Remove unused JUMP_LABEL_NOP_SIZE

JUMP_LABEL_NOP_SIZE is now unused, remove it.

Fixes: 001951bea748 ("jump_label, x86: Add variable length patching support")
Reported-by: Miroslav Benes <mbenes@suse.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/YJ00zxsvocDV5vLU@hirez.programming.kicks-ass.net
---
 arch/x86/kernel/jump_label.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/arch/x86/kernel/jump_label.c b/arch/x86/kernel/jump_label.c
index a762dc1c615e..674906fad43b 100644
--- a/arch/x86/kernel/jump_label.c
+++ b/arch/x86/kernel/jump_label.c
@@ -17,8 +17,6 @@
 #include <asm/text-patching.h>
 #include <asm/insn.h>
 
-#define JUMP_LABEL_NOP_SIZE	JMP32_INSN_SIZE
-
 int arch_jump_entry_size(struct jump_entry *entry)
 {
 	struct insn insn = {};

From 48001d26c19f02c33795829ec9fc71a0d8d42413 Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Thu, 13 May 2021 16:15:50 +0200
Subject: [PATCH 15/20] objtool: Reflow handle_jump_alt()

Miroslav figured the code flow in handle_jump_alt() was sub-optimal
with that goto. Reflow the code to make it clearer.

Reported-by: Miroslav Benes <mbenes@suse.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/YJ00lgslY+IpA/rL@hirez.programming.kicks-ass.net
---
 tools/objtool/check.c | 22 +++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 2c6a93edf27e..e5947fbb9e7a 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -1225,17 +1225,9 @@ static int handle_jump_alt(struct objtool_file *file,
 			   struct instruction *orig_insn,
 			   struct instruction **new_insn)
 {
-	if (orig_insn->type == INSN_NOP) {
-do_nop:
-		if (orig_insn->len == 2)
-			file->jl_nop_short++;
-		else
-			file->jl_nop_long++;
+	if (orig_insn->type != INSN_JUMP_UNCONDITIONAL &&
+	    orig_insn->type != INSN_NOP) {
 
-		return 0;
-	}
-
-	if (orig_insn->type != INSN_JUMP_UNCONDITIONAL) {
 		WARN_FUNC("unsupported instruction at jump label",
 			  orig_insn->sec, orig_insn->offset);
 		return -1;
@@ -1252,7 +1244,15 @@ static int handle_jump_alt(struct objtool_file *file,
 			       orig_insn->offset, orig_insn->len,
 			       arch_nop_insn(orig_insn->len));
 		orig_insn->type = INSN_NOP;
-		goto do_nop;
+	}
+
+	if (orig_insn->type == INSN_NOP) {
+		if (orig_insn->len == 2)
+			file->jl_nop_short++;
+		else
+			file->jl_nop_long++;
+
+		return 0;
 	}
 
 	if (orig_insn->len == 2)

From 8852c552402979508fdc395ae07aa8761aa46045 Mon Sep 17 00:00:00 2001
From: Josh Poimboeuf <jpoimboe@redhat.com>
Date: Tue, 18 May 2021 18:59:15 -0500
Subject: [PATCH 16/20] kbuild: Fix objtool dependency for
 'OBJECT_FILES_NON_STANDARD_<obj> := n'

"OBJECT_FILES_NON_STANDARD_vma.o := n" has a dependency bug.  When
objtool source is updated, the affected object doesn't get re-analyzed
by objtool.

Peter's new variable-sized jump label feature relies on objtool
rewriting the object file.  Otherwise the system can fail to boot.  That
effectively upgrades this minor dependency issue to a major bug.

The problem is that variables in prerequisites are expanded early,
during the read-in phase.  The '$(objtool_dep)' variable indirectly uses
'$@', which isn't yet available when the target prerequisites are
evaluated.

Use '.SECONDEXPANSION:' which causes '$(objtool_dep)' to be expanded in
a later phase, after the target-specific '$@' variable has been defined.

Fixes: b9ab5ebb14ec ("objtool: Add CONFIG_STACK_VALIDATION option")
Fixes: ab3257042c26 ("jump_label, x86: Allow short NOPs")
Reported-by: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
---
 scripts/Makefile.build | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 949f723efe53..34d257653fb4 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -268,7 +268,8 @@ define rule_as_o_S
 endef
 
 # Built-in and composite module parts
-$(obj)/%.o: $(src)/%.c $(recordmcount_source) $(objtool_dep) FORCE
+.SECONDEXPANSION:
+$(obj)/%.o: $(src)/%.c $(recordmcount_source) $$(objtool_dep) FORCE
 	$(call if_changed_rule,cc_o_c)
 	$(call cmd,force_checksrc)
 
@@ -349,7 +350,7 @@ cmd_modversions_S =								\
 	fi
 endif
 
-$(obj)/%.o: $(src)/%.S $(objtool_dep) FORCE
+$(obj)/%.o: $(src)/%.S $$(objtool_dep) FORCE
 	$(call if_changed_rule,as_o_S)
 
 targets += $(filter-out $(subdir-builtin), $(real-obj-y))

From f1069a8756b9e9f6c055e709740d2d66650f0fb0 Mon Sep 17 00:00:00 2001
From: Vasily Gorbik <gor@linux.ibm.com>
Date: Wed, 19 May 2021 15:03:08 +0200
Subject: [PATCH 17/20] compiler.h: Avoid using inline asm operand modifiers

The expansion of annotate_reachable/annotate_unreachable on s390 will
result in a compiler error if the __COUNTER__ value is high enough.
For example with "i" (154) the "%c0" operand of annotate_reachable
will be expanded to -102:

        -102:
        .pushsection .discard.reachable
        .long -102b - .
        .popsection

This is a quirk of the gcc backend for s390, it interprets the %c0
as a signed byte value. Avoid using operand modifiers in this case
by simply converting __COUNTER__ to string, with the same result,
but in an arch assembler independent way.

Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/patch-1.thread-1a26be.git-930d1b44844a.your-ad-here.call-01621428935-ext-2104@work.hours
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Miroslav Benes <mbenes@suse.cz>
Cc: Borislav Petkov <bp@suse.de>
Cc: linux-kernel@vger.kernel.org
---
 include/linux/compiler.h | 22 ++++++++++++++--------
 1 file changed, 14 insertions(+), 8 deletions(-)

diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index df5b405e6305..77047904cf70 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -115,18 +115,24 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
  * The __COUNTER__ based labels are a hack to make each instance of the macros
  * unique, to convince GCC not to merge duplicate inline asm statements.
  */
-#define annotate_reachable() ({						\
-	asm volatile("%c0:\n\t"						\
+#define __stringify_label(n) #n
+
+#define __annotate_reachable(c) ({					\
+	asm volatile(__stringify_label(c) ":\n\t"			\
 		     ".pushsection .discard.reachable\n\t"		\
-		     ".long %c0b - .\n\t"				\
-		     ".popsection\n\t" : : "i" (__COUNTER__));		\
+		     ".long " __stringify_label(c) "b - .\n\t"		\
+		     ".popsection\n\t");				\
 })
-#define annotate_unreachable() ({					\
-	asm volatile("%c0:\n\t"						\
+#define annotate_reachable() __annotate_reachable(__COUNTER__)
+
+#define __annotate_unreachable(c) ({					\
+	asm volatile(__stringify_label(c) ":\n\t"			\
 		     ".pushsection .discard.unreachable\n\t"		\
-		     ".long %c0b - .\n\t"				\
-		     ".popsection\n\t" : : "i" (__COUNTER__));		\
+		     ".long " __stringify_label(c) "b - .\n\t"		\
+		     ".popsection\n\t");				\
 })
+#define annotate_unreachable() __annotate_unreachable(__COUNTER__)
+
 #define ASM_UNREACHABLE							\
 	"999:\n\t"							\
 	".pushsection .discard.unreachable\n\t"				\

From c199f64ff93c48a45add92eee4456ffcabfc838e Mon Sep 17 00:00:00 2001
From: Vasily Gorbik <gor@linux.ibm.com>
Date: Wed, 19 May 2021 15:03:13 +0200
Subject: [PATCH 18/20] instrumentation.h: Avoid using inline asm operand
 modifiers

The expansion of instrumentation_begin/instrumentation_end on s390 will
result in a compiler error if the __COUNTER__ value is high enough.
For example with "i" (154) the "%c0" operand of annotate_reachable
will be expanded to -102:

        -102:
        .pushsection .discard.instr_begin
        .long -102b - .
        .popsection

This is a quirk of the gcc backend for s390, it interprets the %c0
as a signed byte value. Avoid using operand modifiers in this case
by simply converting __COUNTER__ to string, with the same result,
but in an arch assembler independent way.

Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/patch-2.thread-1a26be.git-1a26be80cb18.your-ad-here.call-01621428935-ext-2104@work.hours
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Miroslav Benes <mbenes@suse.cz>
Cc: Borislav Petkov <bp@suse.de>
Cc: linux-kernel@vger.kernel.org
---
 include/linux/instrumentation.h | 20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/include/linux/instrumentation.h b/include/linux/instrumentation.h
index 93e2ad67fc10..fa2cd8c63dcc 100644
--- a/include/linux/instrumentation.h
+++ b/include/linux/instrumentation.h
@@ -4,13 +4,16 @@
 
 #if defined(CONFIG_DEBUG_ENTRY) && defined(CONFIG_STACK_VALIDATION)
 
+#include <linux/stringify.h>
+
 /* Begin/end of an instrumentation safe region */
-#define instrumentation_begin() ({					\
-	asm volatile("%c0: nop\n\t"						\
+#define __instrumentation_begin(c) ({					\
+	asm volatile(__stringify(c) ": nop\n\t"				\
 		     ".pushsection .discard.instr_begin\n\t"		\
-		     ".long %c0b - .\n\t"				\
-		     ".popsection\n\t" : : "i" (__COUNTER__));		\
+		     ".long " __stringify(c) "b - .\n\t"		\
+		     ".popsection\n\t");				\
 })
+#define instrumentation_begin() __instrumentation_begin(__COUNTER__)
 
 /*
  * Because instrumentation_{begin,end}() can nest, objtool validation considers
@@ -43,12 +46,13 @@
  * To avoid this, have _end() be a NOP instruction, this ensures it will be
  * part of the condition block and does not escape.
  */
-#define instrumentation_end() ({					\
-	asm volatile("%c0: nop\n\t"					\
+#define __instrumentation_end(c) ({					\
+	asm volatile(__stringify(c) ": nop\n\t"				\
 		     ".pushsection .discard.instr_end\n\t"		\
-		     ".long %c0b - .\n\t"				\
-		     ".popsection\n\t" : : "i" (__COUNTER__));		\
+		     ".long " __stringify(c) "b - .\n\t"		\
+		     ".popsection\n\t");				\
 })
+#define instrumentation_end() __instrumentation_end(__COUNTER__)
 #else
 # define instrumentation_begin()	do { } while(0)
 # define instrumentation_end()		do { } while(0)

From d33b9035e14a35f6f2a5f067f0b156a93581811d Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Fri, 11 Jun 2021 08:33:36 +0200
Subject: [PATCH 19/20] objtool: Improve reloc hash size guestimate

Nathan reported that LLVM ThinLTO builds have a performance regression
with commit 25cf0d8aa2a3 ("objtool: Rewrite hashtable sizing"). Sami
was quick to note that this is due to their use of -ffunction-sections.

As a result the .text section is small and basing the number of relocs
off of that no longer works. Instead have read_sections() compute the
sum of all SHF_EXECINSTR sections and use that.

Fixes: 25cf0d8aa2a3 ("objtool: Rewrite hashtable sizing")
Reported-by: Nathan Chancellor <nathan@kernel.org>
Debugged-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Link: https://lkml.kernel.org/r/YMJpGLuGNsGtA5JJ@hirez.programming.kicks-ass.net
---
 tools/objtool/elf.c                 | 11 ++++-------
 tools/objtool/include/objtool/elf.h |  1 +
 2 files changed, 5 insertions(+), 7 deletions(-)

diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index a8a0ee21f71a..2371ccc412eb 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -288,6 +288,9 @@ static int read_sections(struct elf *elf)
 		}
 		sec->len = sec->sh.sh_size;
 
+		if (sec->sh.sh_flags & SHF_EXECINSTR)
+			elf->text_size += sec->len;
+
 		list_add_tail(&sec->list, &elf->sections);
 		elf_hash_add(section, &sec->hash, sec->idx);
 		elf_hash_add(section_name, &sec->name_hash, str_hash(sec->name));
@@ -581,13 +584,7 @@ static int read_relocs(struct elf *elf)
 	unsigned int symndx;
 	unsigned long nr_reloc, max_reloc = 0, tot_reloc = 0;
 
-	sec = find_section_by_name(elf, ".text");
-	if (!sec) {
-		WARN("no .text");
-		return -1;
-	}
-
-	if (!elf_alloc_hash(reloc, sec->len / 16))
+	if (!elf_alloc_hash(reloc, elf->text_size / 16))
 		return -1;
 
 	list_for_each_entry(sec, &elf->sections, list) {
diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h
index 90082751f851..e34395047530 100644
--- a/tools/objtool/include/objtool/elf.h
+++ b/tools/objtool/include/objtool/elf.h
@@ -83,6 +83,7 @@ struct elf {
 	int fd;
 	bool changed;
 	char *name;
+	unsigned int text_size;
 	struct list_head sections;
 
 	int symbol_bits;

From e31694e0a7a709293319475d8001e05e31f2178c Mon Sep 17 00:00:00 2001
From: Josh Poimboeuf <jpoimboe@redhat.com>
Date: Wed, 23 Jun 2021 10:42:28 -0500
Subject: [PATCH 20/20] objtool: Don't make .altinstructions writable

When objtool creates the .altinstructions section, it sets the SHF_WRITE
flag to make the section writable -- unless the section had already been
previously created by the kernel.  The mismatch between kernel-created
and objtool-created section flags can cause failures with external
tooling (kpatch-build).  And the section doesn't need to be writable
anyway.

Make the section flags consistent with the kernel's.

Fixes: 9bc0bb50727c ("objtool/x86: Rewrite retpoline thunk calls")
Reported-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/6c284ae89717889ea136f9f0064d914cd8329d31.1624462939.git.jpoimboe@redhat.com
---
 tools/objtool/arch/x86/decode.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c
index 523aa4157f80..bc821056aba9 100644
--- a/tools/objtool/arch/x86/decode.c
+++ b/tools/objtool/arch/x86/decode.c
@@ -684,7 +684,7 @@ static int elf_add_alternative(struct elf *elf,
 	sec = find_section_by_name(elf, ".altinstructions");
 	if (!sec) {
 		sec = elf_create_section(elf, ".altinstructions",
-					 SHF_WRITE, size, 0);
+					 SHF_ALLOC, size, 0);
 
 		if (!sec) {
 			WARN_ELF("elf_create_section");