Add signal handling support for x86_64.

Note that x86_64 has only _rt signal handlers. This implementation
attempts to share code with the x86_32 implementation.

Reported-by: Timothy Pearson <tpearson@raptorengineering.com>
Suggested-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Allan Wirth <awirth@akamai.com>

---
 linux-user/signal.c      | 344 ++++++++++++++++++++++++++++++++++++-----------
 target-i386/cpu.h        |   2 +
 target-i386/fpu_helper.c |  12 ++
 3 files changed, 282 insertions(+), 76 deletions(-)

-- 
1.9.1

On 9 July 2016 at 21:07, Wirth, Allan <awirth@akamai.com> wrote:
> Note that x86_64 has only _rt signal handlers. This implementation
> attempts to share code with the x86_32 implementation.
>
> Reported-by: Timothy Pearson <tpearson@raptorengineering.com>
> Suggested-by: Peter Maydell <peter.maydell@linaro.org>
> Signed-off-by: Allan Wirth <awirth@akamai.com>

Thanks. This mostly looks good; I have one comment below about
a definite bug, and the rest are minor style comments.

The commit message subject line should start with a "linux-user: " prefix.

> ---
>  linux-user/signal.c      | 344 ++++++++++++++++++++++++++++++++++++-----------
>  target-i386/cpu.h        |   2 +
>  target-i386/fpu_helper.c |  12 ++
>  3 files changed, 282 insertions(+), 76 deletions(-)
>
> diff --git a/linux-user/signal.c b/linux-user/signal.c
> index 9d98045..edca9e4 100644
> --- a/linux-user/signal.c
> +++ b/linux-user/signal.c
> @@ -253,8 +253,7 @@ int do_sigprocmask(int how, const sigset_t *set, sigset_t *oldset)
>      return 0;
>  }
>
> -#if !defined(TARGET_OPENRISC) && !defined(TARGET_UNICORE32) && \
> -    !defined(TARGET_X86_64)
> +#if !defined(TARGET_OPENRISC) && !defined(TARGET_UNICORE32)
>  /* Just set the guest's signal mask to the specified value; the
>   * caller is assumed to have called block_signals() already.
>   */
> @@ -789,9 +788,8 @@ int do_sigaction(int sig, const struct target_sigaction *act,
>      return ret;
>  }
>
> -#if defined(TARGET_I386) && TARGET_ABI_BITS == 32
> -
> -/* from the Linux kernel */
> +#if defined(TARGET_I386)
> +/* from the Linux kernel - /arch/x86/include/uapi/asm/sigcontext.h */
>
>  struct target_fpreg {
>      uint16_t significand[4];
> @@ -805,7 +803,7 @@ struct target_fpxreg {
>  };
>
>  struct target_xmmreg {
> -    abi_ulong element[4];
> +    uint32_t element[4];
>  };
>
>  struct target_fpstate {
> @@ -830,33 +828,117 @@ struct target_fpstate {
>      abi_ulong padding[56];
>  };
>
> -#define X86_FXSR_MAGIC         0x0000
> +struct target_fpstate_32 {
> +    /* Regular FPU environment */
> +    uint32_t cw;
> +    uint32_t sw;
> +    uint32_t tag;
> +    uint32_t ipoff;
> +    uint32_t cssel;
> +    uint32_t dataoff;
> +    uint32_t datasel;
> +    struct target_fpreg _st[8];

Better to avoid the leading underscores.

> +    uint16_t  status;
> +    uint16_t  magic;          /* 0xffff = regular FPU data only */
>
> -struct target_sigcontext {
> +    /* FXSR FPU environment */
> +    uint32_t _fxsr_env[6];   /* FXSR FPU env is ignored */
> +    uint32_t mxcsr;
> +    uint32_t reserved;
> +    struct target_fpxreg _fxsr_st[8]; /* FXSR FPU reg data is ignored */
> +    struct target_xmmreg _xmm[8];
> +    uint32_t padding[56];
> +};
> +
> +struct target_fpstate_64 {
> +    /* FXSAVE format */
> +    uint16_t cw;
> +    uint16_t sw;
> +    uint16_t twd;
> +    uint16_t fop;
> +    uint64_t rip;
> +    uint64_t rdp;
> +    uint32_t mxcsr;
> +    uint32_t mxcsr_mask;
> +    uint32_t st_space[32];
> +    uint32_t xmm_space[64];
> +    uint32_t reserved[24];
> +};
> +
> +#ifndef TARGET_X86_64
> +# define target_fpstate target_fpstate_32
> +#else
> +# define target_fpstate target_fpstate_64
> +#endif
> +
> +struct target_sigcontext_32 {
>      uint16_t gs, __gsh;
>      uint16_t fs, __fsh;
>      uint16_t es, __esh;
>      uint16_t ds, __dsh;
> -    abi_ulong edi;
> -    abi_ulong esi;
> -    abi_ulong ebp;
> -    abi_ulong esp;
> -    abi_ulong ebx;
> -    abi_ulong edx;
> -    abi_ulong ecx;
> -    abi_ulong eax;
> -    abi_ulong trapno;
> -    abi_ulong err;
> -    abi_ulong eip;
> +    uint32_t edi;
> +    uint32_t esi;
> +    uint32_t ebp;
> +    uint32_t esp;
> +    uint32_t ebx;
> +    uint32_t edx;
> +    uint32_t ecx;
> +    uint32_t eax;
> +    uint32_t trapno;
> +    uint32_t err;
> +    uint32_t eip;
>      uint16_t cs, __csh;
> -    abi_ulong eflags;
> -    abi_ulong esp_at_signal;
> +    uint32_t eflags;
> +    uint32_t esp_at_signal;
>      uint16_t ss, __ssh;
> -    abi_ulong fpstate; /* pointer */
> -    abi_ulong oldmask;
> -    abi_ulong cr2;
> +    uint32_t fpstate; /* pointer */
> +    uint32_t oldmask;
> +    uint32_t cr2;
>  };
>
> +struct target_sigcontext_64 {
> +    uint64_t r8;
> +    uint64_t r9;
> +    uint64_t r10;
> +    uint64_t r11;
> +    uint64_t r12;
> +    uint64_t r13;
> +    uint64_t r14;
> +    uint64_t r15;
> +
> +    uint64_t rdi;
> +    uint64_t rsi;
> +    uint64_t rbp;
> +    uint64_t rbx;
> +    uint64_t rdx;
> +    uint64_t rax;
> +    uint64_t rcx;
> +    uint64_t rsp;
> +    uint64_t rip;
> +
> +    uint64_t eflags;
> +
> +    uint16_t cs;
> +    uint16_t gs;
> +    uint16_t fs;
> +    uint16_t ss;
> +
> +    uint64_t err;
> +    uint64_t trapno;
> +    uint64_t oldmask;
> +    uint64_t cr2;
> +
> +    uint64_t fpstate; /* pointer */
> +    uint64_t padding[8];
> +};
> +
> +#ifndef TARGET_X86_64
> +# define target_sigcontext target_sigcontext_32
> +#else
> +# define target_sigcontext target_sigcontext_64
> +#endif
> +
> +/* see Linux/include/uapi/asm-generic/ucontext.h */
>  struct target_ucontext {
>      abi_ulong         tuc_flags;
>      abi_ulong         tuc_link;
> @@ -865,6 +947,7 @@ struct target_ucontext {
>      target_sigset_t   tuc_sigmask;  /* mask last for extensibility */
>  };
>
> +#ifndef TARGET_X86_64
>  struct sigframe
>  {
>      abi_ulong pretcode;
> @@ -887,6 +970,18 @@ struct rt_sigframe
>      char retcode[8];
>  };
>
> +#else
> +
> +struct rt_sigframe
> +{

This brace should be on the line before. If you run your patch
through scripts/checkpatch.pl it will catch this nit (and
another ten coding style issues that I'm not going to bother
to list out below).

> +    abi_ulong pretcode;
> +    struct target_ucontext uc;
> +    struct target_siginfo info;
> +    struct target_fpstate fpstate;
> +};
> +
> +#endif
> +
>  /*
>   * Set up a signal frame.
>   */
> @@ -897,6 +992,7 @@ static void setup_sigcontext(struct target_sigcontext *sc,
>          abi_ulong fpstate_addr)
>  {
>      CPUState *cs = CPU(x86_env_get_cpu(env));
> +#ifndef TARGET_X86_64
>      uint16_t magic;
>
>      /* already locked in setup_frame() */
> @@ -929,12 +1025,49 @@ static void setup_sigcontext(struct target_sigcontext *sc,
>      /* non-iBCS2 extensions.. */
>      __put_user(mask, &sc->oldmask);
>      __put_user(env->cr[2], &sc->cr2);
> +#else
> +    __put_user(env->regs[8], &sc->r8);
> +    __put_user(env->regs[9], &sc->r9);
> +    __put_user(env->regs[10], &sc->r10);
> +    __put_user(env->regs[11], &sc->r11);
> +    __put_user(env->regs[12], &sc->r12);
> +    __put_user(env->regs[13], &sc->r13);
> +    __put_user(env->regs[14], &sc->r14);
> +    __put_user(env->regs[15], &sc->r15);
> +
> +    __put_user(env->regs[R_EDI], &sc->rdi);
> +    __put_user(env->regs[R_ESI], &sc->rsi);
> +    __put_user(env->regs[R_EBP], &sc->rbp);
> +    __put_user(env->regs[R_EBX], &sc->rbx);
> +    __put_user(env->regs[R_EDX], &sc->rdx);
> +    __put_user(env->regs[R_EAX], &sc->rax);
> +    __put_user(env->regs[R_ECX], &sc->rcx);
> +    __put_user(env->regs[R_ESP], &sc->rsp);
> +    __put_user(env->eip, &sc->rip);
> +
> +    __put_user(env->eflags, &sc->eflags);
> +
> +    __put_user(env->segs[R_CS].selector, &sc->cs);
> +    __put_user((uint16_t)0, &sc->gs);
> +    __put_user((uint16_t)0, &sc->fs);
> +    __put_user(env->segs[R_SS].selector, &sc->ss);
> +
> +    __put_user(env->error_code, &sc->err);
> +    __put_user(cs->exception_index, &sc->trapno);
> +    __put_user(mask, &sc->oldmask);
> +    __put_user(env->cr[2], &sc->cr2);
> +
> +    /* fpstate_addr must be 16 byte aligned for fxsave */
> +    assert (! (fpstate_addr & 0xf));
> +
> +    cpu_x86_fxsave(env, fpstate_addr);
> +    __put_user(fpstate_addr, &sc->fpstate);
> +#endif
>  }
>
>  /*
>   * Determine which stack to use..
>   */
> -

Stray whitespace change.

>  static inline abi_ulong
>  get_sigframe(struct target_sigaction *ka, CPUX86State *env, size_t frame_size)
>  {
> @@ -942,63 +1075,98 @@ get_sigframe(struct target_sigaction *ka, CPUX86State *env, size_t frame_size)
>
>      /* Default to using normal stack */
>      esp = env->regs[R_ESP];
> +#ifdef TARGET_X86_64
> +    esp -= 128; /* this is the redzone */
> +#endif
> +
>      /* This is the X/Open sanctioned signal stack switching.  */
>      if (ka->sa_flags & TARGET_SA_ONSTACK) {
>          if (sas_ss_flags(esp) == 0) {
>              esp = target_sigaltstack_used.ss_sp + target_sigaltstack_used.ss_size;
>          }
> +#ifndef TARGET_X86_64

This would be better after the "} else {" so we don't have mismatched
nesting of #if..#endif and if..else...

>      } else {
> -
>          /* This is the legacy signal stack switching. */
>          if ((env->segs[R_SS].selector & 0xffff) != __USER_DS &&
>                  !(ka->sa_flags & TARGET_SA_RESTORER) &&
>                  ka->sa_restorer) {
>              esp = (unsigned long) ka->sa_restorer;
>          }
> +#endif
>      }
> +
> +#ifndef TARGET_X86_64
>      return (esp - frame_size) & -8ul;
> +#else
> +    return ((esp - frame_size) & (~15ul)) - 8;
> +#endif
>  }
>
> -/* compare linux/arch/i386/kernel/signal.c:setup_frame() */
> -static void setup_frame(int sig, struct target_sigaction *ka,
> -                        target_sigset_t *set, CPUX86State *env)
> +/* compare linux/arch/i386/kernel/signal.c:setup_rt_frame() */
> +static void setup_rt_frame(int sig, struct target_sigaction *ka,
> +                           target_siginfo_t *info,
> +                           target_sigset_t *set, CPUX86State *env)

Why have you switched the order of these two functions? It makes the
diff very hard to read :-(

>  {
>      abi_ulong frame_addr;
> -    struct sigframe *frame;
> +#ifndef TARGET_X86_64
> +    abi_ulong addr;
> +#endif
> +    struct rt_sigframe *frame;
>      int i;
>
>      frame_addr = get_sigframe(ka, env, sizeof(*frame));
> -    trace_user_setup_frame(env, frame_addr);
> +    trace_user_setup_rt_frame(env, frame_addr);
>
>      if (!lock_user_struct(VERIFY_WRITE, frame, frame_addr, 0))
>          goto give_sigsegv;
>
> +    /* These fields are only in rt_sigframe on 32 bit...? */

Yes; you can remove the "?" from the comment. (They correspond
to setting up arguments on the stack for the signal handler.
x86-64's ABI passes arguments in registers; see later.)

> +#ifndef TARGET_X86_64
>      __put_user(sig, &frame->sig);
> +    addr = frame_addr + offsetof(struct rt_sigframe, info);
> +    __put_user(addr, &frame->pinfo);
> +    addr = frame_addr + offsetof(struct rt_sigframe, uc);
> +    __put_user(addr, &frame->puc);
> +#endif
> +    if (info) {
> +        tswap_siginfo(&frame->info, info);
> +    }
>
> -    setup_sigcontext(&frame->sc, &frame->fpstate, env, set->sig[0],
> -            frame_addr + offsetof(struct sigframe, fpstate));
> +    /* Create the ucontext.  */
> +    __put_user(0, &frame->uc.tuc_flags);
> +    __put_user(0, &frame->uc.tuc_link);
> +    __put_user(target_sigaltstack_used.ss_sp, &frame->uc.tuc_stack.ss_sp);
> +    __put_user(sas_ss_flags(get_sp_from_cpustate(env)),
> +               &frame->uc.tuc_stack.ss_flags);
> +    __put_user(target_sigaltstack_used.ss_size,
> +               &frame->uc.tuc_stack.ss_size);
> +    setup_sigcontext(&frame->uc.tuc_mcontext, &frame->fpstate, env,
> +            set->sig[0], frame_addr + offsetof(struct rt_sigframe, fpstate));
>
> -    for(i = 1; i < TARGET_NSIG_WORDS; i++) {
> -        __put_user(set->sig[i], &frame->extramask[i - 1]);
> +    for(i = 0; i < TARGET_NSIG_WORDS; i++) {
> +        __put_user(set->sig[i], &frame->uc.tuc_sigmask.sig[i]);
>      }
>
>      /* Set up to return from userspace.  If provided, use a stub
>         already in userspace.  */
> +#ifndef TARGET_X86_64
>      if (ka->sa_flags & TARGET_SA_RESTORER) {
>          __put_user(ka->sa_restorer, &frame->pretcode);
>      } else {
>          uint16_t val16;
> -        abi_ulong retcode_addr;
> -        retcode_addr = frame_addr + offsetof(struct sigframe, retcode);
> -        __put_user(retcode_addr, &frame->pretcode);
> -        /* This is popl %eax ; movl $,%eax ; int $0x80 */
> -        val16 = 0xb858;
> -        __put_user(val16, (uint16_t *)(frame->retcode+0));
> -        __put_user(TARGET_NR_sigreturn, (int *)(frame->retcode+2));
> +        addr = frame_addr + offsetof(struct rt_sigframe, retcode);
> +        __put_user(addr, &frame->pretcode);
> +        /* This is movl $,%eax ; int $0x80 */
> +        __put_user(0xb8, (char *)(frame->retcode+0));
> +        __put_user(TARGET_NR_rt_sigreturn, (int *)(frame->retcode+1));
>          val16 = 0x80cd;
> -        __put_user(val16, (uint16_t *)(frame->retcode+6));
> +        __put_user(val16, (uint16_t *)(frame->retcode+5));
>      }
> -
> +#else
> +    /// XXX: Would be slightly better to return -EFAULT here if test fails
> +    assert(ka->sa_flags & TARGET_SA_RESTORER);

Don't assert() on things the guest can provoke, please.

> +    __put_user(ka->sa_restorer, &frame->pretcode);
> +#endif
>
>      /* Set up registers for signal handler */
>      env->regs[R_ESP] = frame_addr;

If you try a test program that registers a handler and prints
the arguments to the signal handler (either just the signal
number, or all 3 arguments if you use sigaction and set SA_SIGINFO)
you will find that your code doesn't correctly pass the parameters
for x86-64, because you aren't setting the necessary registers here.
Compare
http://lxr.free-electrons.com/source/arch/x86/kernel/signal.c#L496

where we set EAX, EDI, ESI, and EDX.

> @@ -1021,41 +1189,28 @@ give_sigsegv:
>      force_sig(TARGET_SIGSEGV /* , current */);
>  }
>
> -/* compare linux/arch/i386/kernel/signal.c:setup_rt_frame() */
> -static void setup_rt_frame(int sig, struct target_sigaction *ka,
> -                           target_siginfo_t *info,
> -                           target_sigset_t *set, CPUX86State *env)
> +/* compare linux/arch/i386/kernel/signal.c:setup_frame() */
> +static void setup_frame(int sig, struct target_sigaction *ka,
> +                        target_sigset_t *set, CPUX86State *env)
>  {
> -    abi_ulong frame_addr, addr;
> -    struct rt_sigframe *frame;
> +#ifndef TARGET_X86_64
> +    abi_ulong frame_addr;
> +    struct sigframe *frame;
>      int i;
>
>      frame_addr = get_sigframe(ka, env, sizeof(*frame));
> -    trace_user_setup_rt_frame(env, frame_addr);
> +    trace_user_setup_frame(env, frame_addr);
>
>      if (!lock_user_struct(VERIFY_WRITE, frame, frame_addr, 0))
>          goto give_sigsegv;
>
>      __put_user(sig, &frame->sig);
> -    addr = frame_addr + offsetof(struct rt_sigframe, info);
> -    __put_user(addr, &frame->pinfo);
> -    addr = frame_addr + offsetof(struct rt_sigframe, uc);
> -    __put_user(addr, &frame->puc);
> -    tswap_siginfo(&frame->info, info);
>
> -    /* Create the ucontext.  */
> -    __put_user(0, &frame->uc.tuc_flags);
> -    __put_user(0, &frame->uc.tuc_link);
> -    __put_user(target_sigaltstack_used.ss_sp, &frame->uc.tuc_stack.ss_sp);
> -    __put_user(sas_ss_flags(get_sp_from_cpustate(env)),
> -               &frame->uc.tuc_stack.ss_flags);
> -    __put_user(target_sigaltstack_used.ss_size,
> -               &frame->uc.tuc_stack.ss_size);
> -    setup_sigcontext(&frame->uc.tuc_mcontext, &frame->fpstate, env,
> -            set->sig[0], frame_addr + offsetof(struct rt_sigframe, fpstate));
> +    setup_sigcontext(&frame->sc, &frame->fpstate, env, set->sig[0],
> +            frame_addr + offsetof(struct sigframe, fpstate));
>
> -    for(i = 0; i < TARGET_NSIG_WORDS; i++) {
> -        __put_user(set->sig[i], &frame->uc.tuc_sigmask.sig[i]);
> +    for(i = 1; i < TARGET_NSIG_WORDS; i++) {
> +        __put_user(set->sig[i], &frame->extramask[i - 1]);
>      }
>
>      /* Set up to return from userspace.  If provided, use a stub
> @@ -1064,15 +1219,18 @@ static void setup_rt_frame(int sig, struct target_sigaction *ka,
>          __put_user(ka->sa_restorer, &frame->pretcode);
>      } else {
>          uint16_t val16;
> -        addr = frame_addr + offsetof(struct rt_sigframe, retcode);
> -        __put_user(addr, &frame->pretcode);
> -        /* This is movl $,%eax ; int $0x80 */
> -        __put_user(0xb8, (char *)(frame->retcode+0));
> -        __put_user(TARGET_NR_rt_sigreturn, (int *)(frame->retcode+1));
> +        abi_ulong retcode_addr;
> +        retcode_addr = frame_addr + offsetof(struct sigframe, retcode);
> +        __put_user(retcode_addr, &frame->pretcode);
> +        /* This is popl %eax ; movl $,%eax ; int $0x80 */
> +        val16 = 0xb858;
> +        __put_user(val16, (uint16_t *)(frame->retcode+0));
> +        __put_user(TARGET_NR_sigreturn, (int *)(frame->retcode+2));
>          val16 = 0x80cd;
> -        __put_user(val16, (uint16_t *)(frame->retcode+5));
> +        __put_user(val16, (uint16_t *)(frame->retcode+6));
>      }
>
> +
>      /* Set up registers for signal handler */
>      env->regs[R_ESP] = frame_addr;
>      env->eip = ka->_sa_handler;
> @@ -1092,15 +1250,19 @@ give_sigsegv:
>          ka->_sa_handler = TARGET_SIG_DFL;
>      }
>      force_sig(TARGET_SIGSEGV /* , current */);
> +#else
> +    setup_rt_frame(sig, ka, 0, set, env);

Why is this here? setup_frame() should never be called if the
architecture doesn't implement it -- you should adjust the
#if in handle_pending_signal(), and then put the whole
setup_frame() function definition inside an #ifndef TARGET_X86_64.

> +#endif
>  }
>
>  static int
>  restore_sigcontext(CPUX86State *env, struct target_sigcontext *sc)
>  {
> -    unsigned int err = 0;
>      abi_ulong fpstate_addr;
>      unsigned int tmpflags;
> +    unsigned int err = 0;
>
> +#ifndef TARGET_X86_64
>      cpu_x86_load_seg(env, R_GS, tswap16(sc->gs));
>      cpu_x86_load_seg(env, R_FS, tswap16(sc->fs));
>      cpu_x86_load_seg(env, R_ES, tswap16(sc->es));
> @@ -1114,7 +1276,29 @@ restore_sigcontext(CPUX86State *env, struct target_sigcontext *sc)
>      env->regs[R_EDX] = tswapl(sc->edx);
>      env->regs[R_ECX] = tswapl(sc->ecx);
>      env->regs[R_EAX] = tswapl(sc->eax);
> +
>      env->eip = tswapl(sc->eip);
> +#else
> +    env->regs[8] = tswapl(sc->r8);
> +    env->regs[9] = tswapl(sc->r9);
> +    env->regs[10] = tswapl(sc->r10);
> +    env->regs[11] = tswapl(sc->r11);
> +    env->regs[12] = tswapl(sc->r12);
> +    env->regs[13] = tswapl(sc->r13);
> +    env->regs[14] = tswapl(sc->r14);
> +    env->regs[15] = tswapl(sc->r15);
> +
> +    env->regs[R_EDI] = tswapl(sc->rdi);
> +    env->regs[R_ESI] = tswapl(sc->rsi);
> +    env->regs[R_EBP] = tswapl(sc->rbp);
> +    env->regs[R_EBX] = tswapl(sc->rbx);
> +    env->regs[R_EDX] = tswapl(sc->rdx);
> +    env->regs[R_EAX] = tswapl(sc->rax);
> +    env->regs[R_ECX] = tswapl(sc->rcx);
> +    env->regs[R_ESP] = tswapl(sc->rsp);
> +
> +    env->eip = tswapl(sc->rip);
> +#endif
>
>      cpu_x86_load_seg(env, R_CS, lduw_p(&sc->cs) | 3);
>      cpu_x86_load_seg(env, R_SS, lduw_p(&sc->ss) | 3);
> @@ -1128,14 +1312,21 @@ restore_sigcontext(CPUX86State *env, struct target_sigcontext *sc)
>          if (!access_ok(VERIFY_READ, fpstate_addr,
>                         sizeof(struct target_fpstate)))
>              goto badframe;
> +#ifndef TARGET_X86_64
>          cpu_x86_frstor(env, fpstate_addr, 1);
> +#else
> +        cpu_x86_fxrstor(env, fpstate_addr);
> +#endif
>      }
>
>      return err;
> +

Stray whitespace change.

>  badframe:
>      return 1;
>  }
>
> +/* Note: there is no sigreturn on x86_64, there is only rt_sigreturn */
> +#ifndef TARGET_X86_64
>  long do_sigreturn(CPUX86State *env)
>  {
>      struct sigframe *frame;
> @@ -1167,6 +1358,7 @@ badframe:
>      force_sig(TARGET_SIGSEGV);
>      return 0;
>  }
> +#endif
>
>  long do_rt_sigreturn(CPUX86State *env)
>  {
> @@ -1174,7 +1366,7 @@ long do_rt_sigreturn(CPUX86State *env)
>      struct rt_sigframe *frame;
>      sigset_t set;
>
> -    frame_addr = env->regs[R_ESP] - 4;
> +    frame_addr = env->regs[R_ESP] - sizeof(abi_ulong);
>      trace_user_do_rt_sigreturn(env, frame_addr);
>      if (!lock_user_struct(VERIFY_READ, frame, frame_addr, 1))
>          goto badframe;
> diff --git a/target-i386/cpu.h b/target-i386/cpu.h
> index 474b0b9..90410d8 100644
> --- a/target-i386/cpu.h
> +++ b/target-i386/cpu.h
> @@ -1337,6 +1337,8 @@ floatx80 cpu_set_fp80(uint64_t mant, uint16_t upper);
>  void cpu_x86_load_seg(CPUX86State *s, int seg_reg, int selector);
>  void cpu_x86_fsave(CPUX86State *s, target_ulong ptr, int data32);
>  void cpu_x86_frstor(CPUX86State *s, target_ulong ptr, int data32);
> +void cpu_x86_fxsave(CPUX86State *s, target_ulong ptr);
> +void cpu_x86_fxrstor(CPUX86State *s, target_ulong ptr);
>
>  /* you can call this signal handler from your SIGBUS and SIGSEGV
>     signal handlers to inform the virtual CPU of exceptions. non zero
> diff --git a/target-i386/fpu_helper.c b/target-i386/fpu_helper.c
> index 929489b..617fdf2 100644
> --- a/target-i386/fpu_helper.c
> +++ b/target-i386/fpu_helper.c
> @@ -1370,6 +1370,18 @@ void helper_fxrstor(CPUX86State *env, target_ulong ptr)
>      }
>  }
>
> +#if defined(CONFIG_USER_ONLY)
> +void cpu_x86_fxsave(CPUX86State *env, target_ulong ptr)
> +{
> +    helper_fxsave(env, ptr);
> +}
> +
> +void cpu_x86_fxrstor(CPUX86State *env, target_ulong ptr)
> +{
> +    helper_fxrstor(env, ptr);
> +}
> +#endif
> +
>  void helper_xrstor(CPUX86State *env, target_ulong ptr, uint64_t rfbm)
>  {
>      uintptr_t ra = GETPC();
> --
> 1.9.1

thanks
-- PMM