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Re: [Qemu-devel] [PATCH 3/3] linux-user:Signal handling for MIPS64

From: Khansa Butt
Subject: Re: [Qemu-devel] [PATCH 3/3] linux-user:Signal handling for MIPS64
Date: Thu, 29 Dec 2011 15:58:57 +0500

On Wed, Dec 14, 2011 at 9:20 PM, Richard Henderson <address@hidden> wrote:
> On 12/07/2011 09:25 PM, address@hidden wrote:
>> +#if defined(TARGET_MIPS64)
>> +        /* tswapal() do 64 bit swap in case of MIPS64 but
>> +           we need 32 bit swap as sa_flags is 32 bit */
>> +        k->sa_flags = bswap32(act->sa_flags);
>> +#else
>>          k->sa_flags = tswapal(act->sa_flags);
>> +#endif
> The condition in syscall_defs.h is TARGET_MIPS, not TARGET_MIPS64.
> They should match, despite the fact that it doesn't actually matter
> for the 32-bit abis.
>>  #elif defined(TARGET_ABI_MIPSN64)
>> -# warning signal handling not implemented
>> +struct target_sigcontext {
>> +    uint32_t   sc_regmask;     /* Unused */
>> +    uint32_t   sc_status;
> There's no reason to duplicate all this code.  Yes, when someone wrote
> this in the first place, they wrote separate sectons for each mips abi.
> However, as you can see that huge portions of this block are identical,
> this was obviously a mistake.
> Start by changing the original section to #elif defined(TARGET_MIPS)
> and see what needs changing specifically for the ABIs.  I'm not even
> sure there are any differences at all.

The difference lies in setup_frame(). the trampoline function needs
syscall number
    install_sigtramp(frame->sf_code, TARGET_NR_sigreturn);
sigreturn is not defined for MIPS64 instead it has only rt_sigreturn.
I tried with #elif defined(TARGET_MIPS). cross compile the following
small program and run it on
#include <stdio.h>
#include <signal.h>
#include <string.h>
#include <unistd.h>

struct sigaction act;

void sighandler(int signum, siginfo_t *info, void *ptr)
    printf("Received signal %d\n", signum);
    printf("Signal originates from process %lu\n",(unsigned long)info->si_pid);

int main()
    printf("I am %lu\n", (unsigned long)getpid());

    memset(&act, 0, sizeof(act));

    act.sa_sigaction = sighandler;
    act.sa_flags = SA_SIGINFO;

    sigaction(SIGILL, &act, NULL);

    // Waiting

    return 0;

and again I found that only install_sigtramp line is needed to be changed.
keeping  #elif defined(TARGET_MIPS) above signal handling portion, can i use
 #if defined(TARGET_MIPS64)
for install_sigtramp() difference
> r~

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