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Re: [PATCH v7 3/8] Use xml-syscall to compare syscall numbers in arm_linux_sigreturn_return-addr.
- From: Antoine Tremblay <antoine dot tremblay at ericsson dot com>
- To: Pedro Alves <palves at redhat dot com>, Yao Qi <qiyaoltc at gmail dot com>
- Cc: <gdb-patches at sourceware dot org>
- Date: Fri, 11 Dec 2015 08:04:50 -0500
- Subject: Re: [PATCH v7 3/8] Use xml-syscall to compare syscall numbers in arm_linux_sigreturn_return-addr.
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- References: <1449583641-18156-1-git-send-email-antoine dot tremblay at ericsson dot com> <1449583641-18156-4-git-send-email-antoine dot tremblay at ericsson dot com> <86io45ql3x dot fsf at gmail dot com> <566ABA91 dot 5000508 at redhat dot com> <566ABB44 dot 3080004 at gmail dot com> <566ABC0C dot 10101 at redhat dot com> <566AC23B dot 6060800 at ericsson dot com> <566AC5EA dot 4090204 at redhat dot com>
On 12/11/2015 07:47 AM, Pedro Alves wrote:
On 12/11/2015 12:31 PM, Antoine Tremblay wrote:
On 12/11/2015 07:05 AM, Pedro Alves wrote:
On 12/11/2015 12:02 PM, Yao Qi wrote:
On 11/12/15 11:59, Pedro Alves wrote:
but then you might as well just do:
#define ARM_SIGRETURN 119
How about using __NR_sigreturn and __NR_rt_sigreturn directly? like
what patch #6 does.
Those are host/native macros. Only make sense for the running host.
Can't use that in a tdep file, like arm-linux-tdep.c. Otherwise, e.g.,
a x86-hosted cross debugger would be using the x86 __NR_sigreturn, etc.
Exactly that's why I use those only in GDBServer.
Hmm, actually, that sounds wrong.
What about Aarch64 gdbserver debugging Aarch32?
I see that the new code in question in patch #6 is in gdbserver/linux-arm-low.c,
which is not built on Aarch64, but, shouldn't that new arm_sigreturn_next_pc
code be used in the biarch scenario as well?
This is only used if we need software single stepping, I think in that
case hardware single stepping will be used on aarch64 even if stepping
over an arm32 program, Yao can confirm ?
If you just made that 32-bit-specific code compile on Aarch64 it would
be compiling against Aarch64's __NR_sigreturn, which I'd assume is wrong for Aarch32.
Looking at the kernel code in linux/arch/arm64 I see :
include/asm/unistd.h:#define __NR_compat_sigreturn 119
include/asm/unistd.h:#define __NR_compat_rt_sigreturn 173
include/asm/unistd32.h:#define __NR_sigreturn 119
include/asm/unistd32.h:__SYSCALL(__NR_sigreturn,
compat_sys_sigreturn_wrapper)
include/asm/unistd32.h:#define __NR_rt_sigreturn 173
include/asm/unistd32.h:__SYSCALL(__NR_rt_sigreturn,
compat_sys_rt_sigreturn_wrapper)
So I think it's ok... but I can't compile on aarch64 at the moment.
Personally while I like the #define ARM_SIGRETURN 119 better, I think
the xml function is fine.
If you added
#define ARM_LINUX_SIGRETURN 119
to arch/arm-linux.h
you could use it in both places.
That was my first thought, I would be OK with that if Yao is too,
however I think both methods work.