From 0be234a46596cd19eb56d2cf46836de8221afb6b Mon Sep 17 00:00:00 2001 From: Benjamin Herrenschmidt <benh@kernel.crashing.org> Date: Mon, 2 Jun 2008 16:22:59 +1000 Subject: [PATCH] [POWERPC] Fix incorrect enabling of VMX when building signal or user context When building a signal or a ucontext, we can incorrectly set the MSR_VEC bit of the kernel pt_regs->msr before returning to userspace if the task -ever- used VMX. This can lead to funny result if that stack used it in the past, then "lost" it (ie. it wasn't enabled after a context switch for example) and then called get_context. It can end up with VMX enabled and the registers containing values from some other task. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Paul Mackerras <paulus@samba.org> --- arch/powerpc/kernel/signal_64.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/kernel/signal_64.c b/arch/powerpc/kernel/signal_64.c index faeb8f207ea48..da7c058e3731f 100644 --- a/arch/powerpc/kernel/signal_64.c +++ b/arch/powerpc/kernel/signal_64.c @@ -87,6 +87,7 @@ static long setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs, #ifdef CONFIG_ALTIVEC elf_vrreg_t __user *v_regs = (elf_vrreg_t __user *)(((unsigned long)sc->vmx_reserve + 15) & ~0xful); #endif + unsigned long msr = regs->msr; long err = 0; flush_fp_to_thread(current); @@ -102,7 +103,7 @@ static long setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs, /* set MSR_VEC in the MSR value in the frame to indicate that sc->v_reg) * contains valid data. */ - regs->msr |= MSR_VEC; + msr |= MSR_VEC; } /* We always copy to/from vrsave, it's 0 if we don't have or don't * use altivec. @@ -114,6 +115,7 @@ static long setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs, err |= __put_user(&sc->gp_regs, &sc->regs); WARN_ON(!FULL_REGS(regs)); err |= __copy_to_user(&sc->gp_regs, regs, GP_REGS_SIZE); + err |= __put_user(msr, &sc->gp_regs[PT_MSR]); err |= __copy_to_user(&sc->fp_regs, ¤t->thread.fpr, FP_REGS_SIZE); err |= __put_user(signr, &sc->signal); err |= __put_user(handler, &sc->handler); -- GitLab