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) <pet...@infradead.org>
---
arch/x86/kernel/unwind_orc.c | 5 ++++-
tools/objtool/orc_dump.c | 2 +-
2 files changed, 5 insertions(+), 2 deletions(-)
--- a/arch/x86/kernel/unwind_orc.c
+++ b/arch/x86/kernel/unwind_orc.c
@@ -471,7 +471,7 @@ bool unwind_next_frame(struct unwind_sta
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_sta
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: */
--- a/tools/objtool/orc_dump.c
+++ b/tools/objtool/orc_dump.c
@@ -54,7 +54,7 @@ static void print_reg(unsigned int reg,
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
