Michael Ellerman wrote:
"Naveen N. Rao" <naveen.n....@linux.ibm.com> writes:
Michael Ellerman wrote:
diff --git a/arch/powerpc/kernel/vdso/gettimeofday.S
b/arch/powerpc/kernel/vdso/gettimeofday.S
index eb9c81e1c218..0aee255e9cbb 100644
--- a/arch/powerpc/kernel/vdso/gettimeofday.S
+++ b/arch/powerpc/kernel/vdso/gettimeofday.S
@@ -22,12 +22,15 @@
.macro cvdso_call funct call_time=0
.cfi_startproc
PPC_STLU r1, -PPC_MIN_STKFRM(r1)
+ .cfi_adjust_cfa_offset PPC_MIN_STKFRM
mflr r0
- .cfi_register lr, r0
PPC_STLU r1, -PPC_MIN_STKFRM(r1)
+ .cfi_adjust_cfa_offset PPC_MIN_STKFRM
PPC_STL r0, PPC_MIN_STKFRM + PPC_LR_STKOFF(r1)
<snip>
@@ -46,6 +50,7 @@
mtlr r0
.cfi_restore lr
addi r1, r1, 2 * PPC_MIN_STKFRM
+ .cfi_def_cfa_offset 0
Should this be .cfi_adjust_cfa_offset, given that we used that at the
start of the function?
AIUI "adjust x" is offset += x, whereas "def x" is offset = x.
So we could use adjust here, but we'd need to adjust by -(2 * PPC_MIN_STKFRM).
It seemed clearer to just set the offset back to 0, which is what it is
at the start of the function.
I read the first .cfi_adjust_cfa_offset directive (rather than the
.cfi_def_cfa_offset directive) in this macro to be intentionally
retaining the offset to what it was before the VDSO. If that is
desirable, then setting it to 0 here will change it, I _think_.
But I'm not a CFI expert at all, so I'll defer to anyone else who has an
opinion :)
Oh, the above is just my hypothesis. Would be good to get confirmation.
- Naveen
