Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf

Alexei Starovoitov says:

====================
pull-request: bpf 2019-12-11

The following pull-request contains BPF updates for your *net* tree.

We've added 8 non-merge commits during the last 1 day(s) which contain
a total of 10 files changed, 126 insertions(+), 18 deletions(-).

The main changes are:

1) Make BPF trampoline co-exist with ftrace-based tracers, from Alexei.

2) Fix build in minimal configurations, from Arnd.

3) Fix mips, riscv bpf_tail_call limit, from Paul.

4) Fix bpftool segfault, from Toke.

5) Fix samples/bpf, from Daniel.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

arch/mips/net/ebpf_jit.c

@@ -604,6 +604,7 @@ static void emit_const_to_reg(struct jit_ctx *ctx, int dst, u64 value)
 static int emit_bpf_tail_call(struct jit_ctx *ctx, int this_idx)
 {
 	int off, b_off;
+	int tcc_reg;
 
 	ctx->flags |= EBPF_SEEN_TC;
 	/*
@@ -616,14 +617,14 @@ static int emit_bpf_tail_call(struct jit_ctx *ctx, int this_idx)
 	b_off = b_imm(this_idx + 1, ctx);
 	emit_instr(ctx, bne, MIPS_R_AT, MIPS_R_ZERO, b_off);
 	/*
-	 * if (--TCC < 0)
+	 * if (TCC-- < 0)
 	 *     goto out;
 	 */
 	/* Delay slot */
-	emit_instr(ctx, daddiu, MIPS_R_T5,
-		   (ctx->flags & EBPF_TCC_IN_V1) ? MIPS_R_V1 : MIPS_R_S4, -1);
+	tcc_reg = (ctx->flags & EBPF_TCC_IN_V1) ? MIPS_R_V1 : MIPS_R_S4;
+	emit_instr(ctx, daddiu, MIPS_R_T5, tcc_reg, -1);
 	b_off = b_imm(this_idx + 1, ctx);
-	emit_instr(ctx, bltz, MIPS_R_T5, b_off);
+	emit_instr(ctx, bltz, tcc_reg, b_off);
 	/*
 	 * prog = array->ptrs[index];
 	 * if (prog == NULL)

arch/riscv/net/bpf_jit_comp.c

@@ -631,14 +631,14 @@ static int emit_bpf_tail_call(int insn, struct rv_jit_context *ctx)
 		return -1;
 	emit(rv_bgeu(RV_REG_A2, RV_REG_T1, off >> 1), ctx);
 
-	/* if (--TCC < 0)
+	/* if (TCC-- < 0)
 	 *     goto out;
 	 */
 	emit(rv_addi(RV_REG_T1, tcc, -1), ctx);
 	off = (tc_ninsn - (ctx->ninsns - start_insn)) << 2;
 	if (is_13b_check(off, insn))
 		return -1;
-	emit(rv_blt(RV_REG_T1, RV_REG_ZERO, off >> 1), ctx);
+	emit(rv_blt(tcc, RV_REG_ZERO, off >> 1), ctx);
 
 	/* prog = array->ptrs[index];
 	 * if (!prog)

include/linux/bpf.h

@@ -461,6 +461,7 @@ struct bpf_trampoline {
 	struct {
 		struct btf_func_model model;
 		void *addr;
+		bool ftrace_managed;
 	} func;
 	/* list of BPF programs using this trampoline */
 	struct hlist_head progs_hlist[BPF_TRAMP_MAX];

kernel/bpf/btf.c

@@ -3470,6 +3470,7 @@ static u8 bpf_ctx_convert_map[] = {
 	[_id] = __ctx_convert##_id,
 #include <linux/bpf_types.h>
 #undef BPF_PROG_TYPE
+	0, /* avoid empty array */
 };
 #undef BPF_MAP_TYPE
 

kernel/bpf/trampoline.c

@@ -3,6 +3,7 @@
 #include <linux/hash.h>
 #include <linux/bpf.h>
 #include <linux/filter.h>
+#include <linux/ftrace.h>
 
 /* btf_vmlinux has ~22k attachable functions. 1k htab is enough. */
 #define TRAMPOLINE_HASH_BITS 10
@@ -59,6 +60,60 @@ struct bpf_trampoline *bpf_trampoline_lookup(u64 key)
 	return tr;
 }
 
+static int is_ftrace_location(void *ip)
+{
+	long addr;
+
+	addr = ftrace_location((long)ip);
+	if (!addr)
+		return 0;
+	if (WARN_ON_ONCE(addr != (long)ip))
+		return -EFAULT;
+	return 1;
+}
+
+static int unregister_fentry(struct bpf_trampoline *tr, void *old_addr)
+{
+	void *ip = tr->func.addr;
+	int ret;
+
+	if (tr->func.ftrace_managed)
+		ret = unregister_ftrace_direct((long)ip, (long)old_addr);
+	else
+		ret = bpf_arch_text_poke(ip, BPF_MOD_CALL, old_addr, NULL);
+	return ret;
+}
+
+static int modify_fentry(struct bpf_trampoline *tr, void *old_addr, void *new_addr)
+{
+	void *ip = tr->func.addr;
+	int ret;
+
+	if (tr->func.ftrace_managed)
+		ret = modify_ftrace_direct((long)ip, (long)old_addr, (long)new_addr);
+	else
+		ret = bpf_arch_text_poke(ip, BPF_MOD_CALL, old_addr, new_addr);
+	return ret;
+}
+
+/* first time registering */
+static int register_fentry(struct bpf_trampoline *tr, void *new_addr)
+{
+	void *ip = tr->func.addr;
+	int ret;
+
+	ret = is_ftrace_location(ip);
+	if (ret < 0)
+		return ret;
+	tr->func.ftrace_managed = ret;
+
+	if (tr->func.ftrace_managed)
+		ret = register_ftrace_direct((long)ip, (long)new_addr);
+	else
+		ret = bpf_arch_text_poke(ip, BPF_MOD_CALL, NULL, new_addr);
+	return ret;
+}
+
 /* Each call __bpf_prog_enter + call bpf_func + call __bpf_prog_exit is ~50
  * bytes on x86.  Pick a number to fit into PAGE_SIZE / 2
  */
@@ -77,8 +132,7 @@ static int bpf_trampoline_update(struct bpf_trampoline *tr)
 	int err;
 
 	if (fentry_cnt + fexit_cnt == 0) {
-		err = bpf_arch_text_poke(tr->func.addr, BPF_MOD_CALL,
-					 old_image, NULL);
+		err = unregister_fentry(tr, old_image);
 		tr->selector = 0;
 		goto out;
 	}
@@ -105,12 +159,10 @@ static int bpf_trampoline_update(struct bpf_trampoline *tr)
 
 	if (tr->selector)
 		/* progs already running at this address */
-		err = bpf_arch_text_poke(tr->func.addr, BPF_MOD_CALL,
-					 old_image, new_image);
+		err = modify_fentry(tr, old_image, new_image);
 	else
 		/* first time registering */
-		err = bpf_arch_text_poke(tr->func.addr, BPF_MOD_CALL, NULL,
-					 new_image);
+		err = register_fentry(tr, new_image);
 	if (err)
 		goto out;
 	tr->selector++;

samples/bpf/syscall_tp_kern.c

@@ -47,13 +47,27 @@ static __always_inline void count(void *map)
 SEC("tracepoint/syscalls/sys_enter_open")
 int trace_enter_open(struct syscalls_enter_open_args *ctx)
 {
-	count((void *)&enter_open_map);
+	count(&enter_open_map);
+	return 0;
+}
+
+SEC("tracepoint/syscalls/sys_enter_openat")
+int trace_enter_open_at(struct syscalls_enter_open_args *ctx)
+{
+	count(&enter_open_map);
 	return 0;
 }
 
 SEC("tracepoint/syscalls/sys_exit_open")
 int trace_enter_exit(struct syscalls_exit_open_args *ctx)
 {
-	count((void *)&exit_open_map);
+	count(&exit_open_map);
+	return 0;
+}
+
+SEC("tracepoint/syscalls/sys_exit_openat")
+int trace_enter_exit_at(struct syscalls_exit_open_args *ctx)
+{
+	count(&exit_open_map);
 	return 0;
 }

samples/bpf/trace_event_user.c

@@ -37,9 +37,9 @@ static void print_ksym(__u64 addr)
 	}
 
 	printf("%s;", sym->name);
-	if (!strcmp(sym->name, "sys_read"))
+	if (!strstr(sym->name, "sys_read"))
 		sys_read_seen = true;
-	else if (!strcmp(sym->name, "sys_write"))
+	else if (!strstr(sym->name, "sys_write"))
 		sys_write_seen = true;
 }
 

tools/bpf/bpftool/prog.c

@@ -493,7 +493,7 @@ static int do_dump(int argc, char **argv)
 
 	info = &info_linear->info;
 	if (mode == DUMP_JITED) {
-		if (info->jited_prog_len == 0) {
+		if (info->jited_prog_len == 0 || !info->jited_prog_insns) {
 			p_info("no instructions returned");
 			goto err_free;
 		}

tools/bpf/bpftool/xlated_dumper.c

@@ -174,7 +174,7 @@ static const char *print_call(void *private_data,
 	struct kernel_sym *sym;
 
 	if (insn->src_reg == BPF_PSEUDO_CALL &&
-	    (__u32) insn->imm < dd->nr_jited_ksyms)
+	    (__u32) insn->imm < dd->nr_jited_ksyms && dd->jited_ksyms)
 		address = dd->jited_ksyms[insn->imm];
 
 	sym = kernel_syms_search(dd, address);

tools/testing/selftests/bpf/test_ftrace.sh

@@ -0,0 +1,39 @@
+#!/bin/bash
+
+TR=/sys/kernel/debug/tracing/
+clear_trace() { # reset trace output
+    echo > $TR/trace
+}
+
+disable_tracing() { # stop trace recording
+    echo 0 > $TR/tracing_on
+}
+
+enable_tracing() { # start trace recording
+    echo 1 > $TR/tracing_on
+}
+
+reset_tracer() { # reset the current tracer
+    echo nop > $TR/current_tracer
+}
+
+disable_tracing
+clear_trace
+
+echo "" > $TR/set_ftrace_filter
+echo '*printk* *console* *wake* *serial* *lock*' > $TR/set_ftrace_notrace
+
+echo "bpf_prog_test*" > $TR/set_graph_function
+echo "" > $TR/set_graph_notrace
+
+echo function_graph > $TR/current_tracer
+
+enable_tracing
+./test_progs -t fentry
+./test_progs -t fexit
+disable_tracing
+clear_trace
+
+reset_tracer
+
+exit 0