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x86/ftrace: Support objtool vmlinux.o validation in ftrace_64.S 

With objtool vmlinux.o validation of return_to_handler(), now that
objtool has visibility inside the retpoline, jumping from EMPTY state to
a proper function state results in a stack state mismatch.

return_to_handler() is actually quite normal despite the underlying
magic.  Just annotate it as a normal function.

Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/14f48e623f61dbdcd84cf27a56ed8ccae73199ef.1611263462.git.jpoimboe@redhat.com
This commit is contained in:
Josh Poimboeuf 2021-01-21 15:29:31 -06:00
parent 82694854ca
commit 7cae4b1cf1
1 changed files with 2 additions and 3 deletions
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5
arch/x86/kernel/ftrace_64.S
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@ -334,8 +334,7 @@ SYM_FUNC_START(ftrace_graph_caller)
retq
SYM_FUNC_END(ftrace_graph_caller)
SYM_CODE_START(return_to_handler)
UNWIND_HINT_EMPTY
SYM_FUNC_START(return_to_handler)
subq $24, %rsp
/* Save the return values */
@ -350,5 +349,5 @@ SYM_CODE_START(return_to_handler)
movq (%rsp), %rax
addq $24, %rsp
JMP_NOSPEC rdi
SYM_CODE_END(return_to_handler)
SYM_FUNC_END(return_to_handler)
#endif