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objtool: Add module specific retpoline rules 

David allowed retpolines in .init.text, except for modules, which will
trip up objtool retpoline validation, fix that.

Requested-by: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Peter Zijlstra 2018-01-31 10:18:28 +01:00 committed by Ingo Molnar
parent b5bc2231b8
commit ca41b97ed9
4 changed files with 14 additions and 2 deletions
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2
scripts/Makefile.build
View File

@ -256,6 +256,8 @@ __objtool_obj := $(objtree)/tools/objtool/objtool
objtool_args = $(if $(CONFIG_UNWINDER_ORC),orc generate,check)
objtool_args += $(if $(part-of-module), --module,)
ifndef CONFIG_FRAME_POINTER
objtool_args += --no-fp
endif

3
tools/objtool/builtin-check.c
View File

@ -29,7 +29,7 @@
#include "builtin.h"
#include "check.h"
bool no_fp, no_unreachable, retpoline;
bool no_fp, no_unreachable, retpoline, module;
static const char * const check_usage[] = {
"objtool check [<options>] file.o",
@ -40,6 +40,7 @@ const struct option check_options[] = {
OPT_BOOLEAN('f', "no-fp", &no_fp, "Skip frame pointer validation"),
OPT_BOOLEAN('u', "no-unreachable", &no_unreachable, "Skip 'unreachable instruction' warnings"),
OPT_BOOLEAN('r', "retpoline", &retpoline, "Validate retpoline assumptions"),
OPT_BOOLEAN('m', "module", &module, "Indicates the object will be part of a kernel module"),
OPT_END(),
};

2
tools/objtool/builtin.h
View File

@ -20,7 +20,7 @@
#include <subcmd/parse-options.h>
extern const struct option check_options[];
extern bool no_fp, no_unreachable, retpoline;
extern bool no_fp, no_unreachable, retpoline, module;
extern int cmd_check(int argc, const char **argv);
extern int cmd_orc(int argc, const char **argv);

9
tools/objtool/check.c
View File

@ -1958,6 +1958,15 @@ static int validate_retpoline(struct objtool_file *file)
if (insn->retpoline_safe)
continue;
/*
* .init.text code is ran before userspace and thus doesn't
* strictly need retpolines, except for modules which are
* loaded late, they very much do need retpoline in their
* .init.text
*/
if (!strcmp(insn->sec->name, ".init.text") && !module)
continue;
WARN_FUNC("indirect %s found in RETPOLINE build",
insn->sec, insn->offset,
insn->type == INSN_JUMP_DYNAMIC ? "jump" : "call");