[PATCH 4.19 46/48] objtool: Fix stack offset tracking for indirect CFAs

Greg Kroah-Hartman
2020-05-13T10:04:16Z

From: Josh Poimboeuf <jpoimboe@redhat.com>

commit d8dd25a461e4eec7190cb9d66616aceacc5110ad upstream.

When the current frame address (CFA) is stored on the stack (i.e.,
cfa->base == CFI_SP_INDIRECT), objtool neglects to adjust the stack
offset when there are subsequent pushes or pops. This results in bad
ORC data at the end of the ENTER_IRQ_STACK macro, when it puts the
previous stack pointer on the stack and does a subsequent push.

This fixes the following unwinder warning:

WARNING: can't dereference registers at 00000000f0a6bdba for ip interrupt_entry+0x9f/0xa0

Fixes: 627fce14809b ("objtool: Add ORC unwind table generation")
Reported-by: Vince Weaver <vincent.weaver@maine.edu>
Reported-by: Dave Jones <dsj@fb.com>
Reported-by: Steven Rostedt <rostedt@goodmis.org>
Reported-by: Vegard Nossum <vegard.nossum@oracle.com>
Reported-by: Joe Mario <jmario@redhat.com>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Jann Horn <jannh@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/853d5d691b29e250333332f09b8e27410b2d9924.1587808742.git.jpoimboe@redhat.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
tools/objtool/check.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -1315,7 +1315,7 @@ static int update_insn_state_regs(struct
struct cfi_reg *cfa = &state->cfa;
struct stack_op *op = &insn->stack_op;

- if (cfa->base != CFI_SP)
+ if (cfa->base != CFI_SP && cfa->base != CFI_SP_INDIRECT)
return 0;

/* push */