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authorJosh Poimboeuf <jpoimboe@redhat.com>2019-05-13 12:01:32 -0500
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2019-05-22 07:37:35 +0200
commit7b72ca6312abfd2b61aea45ad9f0d2c45bf2a4e9 (patch)
tree4ca65ec254507c0015b780574b799fd5c4c40f42 /tools/objtool
parentb185029f5c41b7c7e4ac5d0f294cc81e56b4c785 (diff)
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objtool: Fix function fallthrough detection
commit e6f393bc939d566ce3def71232d8013de9aaadde upstream. When a function falls through to the next function due to a compiler bug, objtool prints some obscure warnings. For example: drivers/regulator/core.o: warning: objtool: regulator_count_voltages()+0x95: return with modified stack frame drivers/regulator/core.o: warning: objtool: regulator_count_voltages()+0x0: stack state mismatch: cfa1=7+32 cfa2=7+8 Instead it should be printing: drivers/regulator/core.o: warning: objtool: regulator_supply_is_couple() falls through to next function regulator_count_voltages() This used to work, but was broken by the following commit: 13810435b9a7 ("objtool: Support GCC 8's cold subfunctions") The padding nops at the end of a function aren't actually part of the function, as defined by the symbol table. So the 'func' variable in validate_branch() is getting cleared to NULL when a padding nop is encountered, breaking the fallthrough detection. If the current instruction doesn't have a function associated with it, just consider it to be part of the previously detected function by not overwriting the previous value of 'func'. Reported-by: kbuild test robot <lkp@intel.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: <stable@vger.kernel.org> Fixes: 13810435b9a7 ("objtool: Support GCC 8's cold subfunctions") Link: http://lkml.kernel.org/r/546d143820cd08a46624ae8440d093dd6c902cae.1557766718.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'tools/objtool')
-rw-r--r--tools/objtool/check.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index ef152daccc33..46be34576620 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -1805,7 +1805,8 @@ static int validate_branch(struct objtool_file *file, struct instruction *first,
return 1;
}
- func = insn->func ? insn->func->pfunc : NULL;
+ if (insn->func)
+ func = insn->func->pfunc;
if (func && insn->ignore) {
WARN_FUNC("BUG: why am I validating an ignored function?",