Hello!
The attached patch enables the sigaltstack syscall in qemu-sh4.
The following minimal test code verifies that sigaltstack works as
expected:
=============================================================
#include <setjmp.h>
#include <signal.h>
#include <stdlib.h>
#include <stdio.h>
jmp_buf exit_jmp;
void handler(int x)
{
longjmp(exit_jmp, 1);
}
int f(void)
{
return f();
}
int main(void)
{
stack_t sigstack;
sigstack.ss_sp = malloc(1024*1024);
sigstack.ss_size = 1024*1024;
sigstack.ss_flags = 0;
sigaltstack(&sigstack, NULL);
struct sigaction sa;
sa.sa_handler = handler;
sigemptyset(&sa.sa_mask);
sa.sa_flags = SA_ONSTACK;
sigaction(SIGSEGV, &sa, NULL);
if (setjmp(exit_jmp) == 0)
{
return f();
}
puts("recovered");
return 0;
}
=============================================================
Without sigaltstack enabled, this code produces a segmentation fault.
With sigaltstack enabled, it prints out "recovered".
Also posted on qemu-devel mailing list:
> http://lists.nongnu.org/archive/html/qemu-devel/2015-11/msg04300.html
> http://lists.nongnu.org/archive/html/qemu-devel/2015-11/msg04301.html
Cheers,
Adrian
** Patch added: "Patch to enable sigaltstack in qemu-sh4"
https://bugs.launchpad.net/qemu/+bug/1516408/+attachment/4521728/+files/0001-linux-user-Enable-sigaltstack-syscall-for-sh4.patch
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https://bugs.launchpad.net/bugs/1516408
Title:
sh4: Unsupported syscall: 186
Status in QEMU:
New
Bug description:
Hello!
I'm currently testing qemu as a possibility to set up a buildd for the
Debian sh4 port.
I set up qemu and an sh4 chroot as described in the Debian Wiki [1].
This seems to be working mostly fine (besides the fact that qemu
segfaults on an amd64 host while it runs fine on an i386 host, I'll
file a separate bug report). However, when installing python3.4 in the
sh4 chroot, qemu repeatedly printed an error message about an
unimplemented syscall: 186:
qemu: Unsupported syscall: 186
From the source code in linux-user/sh4/syscall_nr.h it's apparent that
186 is defined as
#define TARGET_NR_sigaltstack 186
Looking at the implementation part, it becomes obvious that this
syscall is not enabled for sh4:
#if defined(TARGET_I386) || defined(TARGET_ARM) || defined(TARGET_MIPS) || \
defined(TARGET_SPARC) || defined(TARGET_PPC) || defined(TARGET_ALPHA) || \
defined(TARGET_M68K) || defined(TARGET_S390X) || defined(TARGET_OPENRISC)
ret = do_sigaltstack(arg1, arg2, get_sp_from_cpustate((CPUArchState
*)cpu_env));
break;
#else
goto unimplemented;
#endif
Is there any particular reason why TARGET_NR_sigaltstack is not
enabled on sh4? If not, could you enable it?
Thanks,
Adrian
> [1] https://wiki.debian.org/QemuUserEmulation
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