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x86/unwind/orc: Detect the end of the stack

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The existing UNWIND_HINT_EMPTY annotations happen to be good indicators
of where entry code calls into C code for the first time.  So also use
them to mark the end of the stack for the ORC unwinder.

Use that information to set unwind->error if the ORC unwinder doesn't
unwind all the way to the end.  This will be needed for enabling
HAVE_RELIABLE_STACKTRACE for the ORC unwinder so we can use it with the
livepatch consistency model.

Thanks to Jiri Slaby for teaching the ORCs about the unwind hints.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/lkml/20180518064713.26440-5-jslaby@suse.cz
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Josh Poimboeuf
2018-05-18 08:47:12 +02:00
committed by Ingo Molnar
parent 0c414367c0
commit d31a580266
9 changed files with 52 additions and 29 deletions
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2
tools/objtool/orc_gen.c
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@@ -31,6 +31,8 @@ int create_orc(struct objtool_file *file)
struct cfi_reg *cfa = &insn->state.cfa;
struct cfi_reg *bp = &insn->state.regs[CFI_BP];
orc->end = insn->state.end;
if (cfa->base == CFI_UNDEFINED) {
orc->sp_reg = ORC_REG_UNDEFINED;
continue;