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ARM: linux-user: Restore VFP state from ucontext on sigreturn 

Restore the VFP registers from the ucontext on return from a signal
handler in linux-user mode. This means that signal handlers cannot
accidentally corrupt the interrupted code's VFP state, and allows
them to deliberately modify the state via the ucontext structure.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Riku Voipio <riku.voipio@nokia.com>
This commit is contained in:
Peter Maydell 2010-11-24 15:20:06 +00:00 committed by Riku Voipio
parent 0d871bdbaa
commit 5f9099d9ce
1 changed files with 40 additions and 0 deletions
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40
linux-user/signal.c
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@ -1535,10 +1535,41 @@ badframe:
return 0;
}
static abi_ulong *restore_sigframe_v2_vfp(CPUState *env, abi_ulong *regspace)
{
int i;
abi_ulong magic, sz;
uint32_t fpscr, fpexc;
struct target_vfp_sigframe *vfpframe;
vfpframe = (struct target_vfp_sigframe *)regspace;
__get_user(magic, &vfpframe->magic);
__get_user(sz, &vfpframe->size);
if (magic != TARGET_VFP_MAGIC || sz != sizeof(*vfpframe)) {
return 0;
}
for (i = 0; i < 32; i++) {
__get_user(env->vfp.regs[i], &vfpframe->ufp.fpregs[i]);
}
__get_user(fpscr, &vfpframe->ufp.fpscr);
vfp_set_fpscr(env, fpscr);
__get_user(fpexc, &vfpframe->ufp_exc.fpexc);
/* Sanitise FPEXC: ensure VFP is enabled, FPINST2 is invalid
* and the exception flag is cleared
*/
fpexc |= (1 << 30);
fpexc &= ~((1 << 31) | (1 << 28));
env->vfp.xregs[ARM_VFP_FPEXC] = fpexc;
__get_user(env->vfp.xregs[ARM_VFP_FPINST], &vfpframe->ufp_exc.fpinst);
__get_user(env->vfp.xregs[ARM_VFP_FPINST2], &vfpframe->ufp_exc.fpinst2);
return (abi_ulong*)(vfpframe + 1);
}
static int do_sigframe_return_v2(CPUState *env, target_ulong frame_addr,
struct target_ucontext_v2 *uc)
{
sigset_t host_set;
abi_ulong *regspace;
target_to_host_sigset(&host_set, &uc->tuc_sigmask);
sigprocmask(SIG_SETMASK, &host_set, NULL);
@ -1546,6 +1577,15 @@ static int do_sigframe_return_v2(CPUState *env, target_ulong frame_addr,
if (restore_sigcontext(env, &uc->tuc_mcontext))
return 1;
/* Restore coprocessor signal frame */
regspace = uc->tuc_regspace;
if (arm_feature(env, ARM_FEATURE_VFP)) {
regspace = restore_sigframe_v2_vfp(env, regspace);
if (!regspace) {
return 1;
}
}
if (do_sigaltstack(frame_addr + offsetof(struct target_ucontext_v2, tuc_stack), 0, get_sp_from_cpustate(env)) == -EFAULT)
return 1;