On 07/24/2013 11:25:52 AM, Udma Catalin-Dan-B32721 wrote:
> This breaks the vdso for e500v1/v2 (userspace dies with SIGILL),
since
> KBUILD_CFLAGS doesn't get used when building asm files, and the vdso
> uses mftbu/mftbl which are not being assembled to the form that
> e500v1/v2 support.
>
> We should be setting -mcpu=whatever and -msoft-float in both CFLAGS
and
> AFLAGS, since we don't call "as" directly, and target selection
should
> not differ based on whether we're building a C file or an asm file.
>
> -Scott
[CU] Thank you, Scott. I'll update also AFLAGS.
I have some questions about how you reproduce the SIGILL issue.
I tried to reproduce the issue looking to gettimeofday.S, that uses
mftbu/mftbl. In my tests, I obtained the same output when compiling
this file
for p1021rdb before and after this patch, and also after adding -mcpu
to
AFLAGS: "objdump -d arch/powerpc/kernel/vdso32/gettimeofday.o" looks
the same
for the cases mentioned above:
"mftbu r3" from .S file is decoded to "mfspr r3,269" in "objdump
-d" output
Indeed, for -mcpu=601/power3, the "objdump -d" output is "mftbu r3"
and according to
powerISA this instruction would cause Illegal Instruction error
handler to be invoked
and permits the sw to emulate the instruction.
It probably depends on what the default is for your toolchain.
-Scott
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