The following commit has been merged into the objtool/core branch of tip:
Commit-ID: 87ccc826bf1c9e5ab4c2f649b404e02c63e47622
Gitweb: https://git.kernel.org/tip/87ccc826bf1c9e5ab4c2f649b404e02c63e47622
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate: Wed, 03 Feb 2021 12:02:21 +01:00
Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Wed, 10 Feb 2021 20:53:51 +01:00
x86/unwind/orc: Change REG_SP_INDIRECT
Currently REG_SP_INDIRECT is unused but means (%rsp + offset),
change it to mean (%rsp) + offset.
The reason is that we're going to swizzle stack in the middle of a C
function with non-trivial stack footprint. This means that when the
unwinder finds the ToS, it needs to dereference it (%rsp) and then add
the offset to the next frame, resulting in: (%rsp) + offset
This is somewhat unfortunate, since REG_BP_INDIRECT is used (by DRAP)
and thus needs to retain the current (%rbp + offset).
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Reviewed-by: Miroslav Benes <mbenes@xxxxxxx>
Acked-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
---
arch/x86/kernel/unwind_orc.c | 5 ++++-
tools/objtool/orc_dump.c | 2 +-
2 files changed, 5 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kernel/unwind_orc.c b/arch/x86/kernel/unwind_orc.c
index 73f8001..2a1d47f 100644
--- a/arch/x86/kernel/unwind_orc.c
+++ b/arch/x86/kernel/unwind_orc.c
@@ -471,7 +471,7 @@ bool unwind_next_frame(struct unwind_state *state)
break;
case ORC_REG_SP_INDIRECT:
- sp = state->sp + orc->sp_offset;
+ sp = state->sp;
indirect = true;
break;
@@ -521,6 +521,9 @@ bool unwind_next_frame(struct unwind_state *state)
if (indirect) {
if (!deref_stack_reg(state, sp, &sp))
goto err;
+
+ if (orc->sp_reg == ORC_REG_SP_INDIRECT)
+ sp += orc->sp_offset;
}
/* Find IP, SP and possibly regs: */
diff --git a/tools/objtool/orc_dump.c b/tools/objtool/orc_dump.c
index c53fae9..f5a8508 100644
--- a/tools/objtool/orc_dump.c
+++ b/tools/objtool/orc_dump.c
@@ -55,7 +55,7 @@ static void print_reg(unsigned int reg, int offset)
if (reg == ORC_REG_BP_INDIRECT)
printf("(bp%+d)", offset);
else if (reg == ORC_REG_SP_INDIRECT)
- printf("(sp%+d)", offset);
+ printf("(sp)%+d", offset);
else if (reg == ORC_REG_UNDEFINED)
printf("(und)");
else
|