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authorBenjamin Herrenschmidt <benh@kernel.crashing.org>2008-06-02 10:22:59 +0400
committerPaul Mackerras <paulus@samba.org>2008-06-09 05:32:36 +0400
commit0be234a46596cd19eb56d2cf46836de8221afb6b (patch)
tree5752259ba499e1e0e033df1fb59b8c57521a91ba /arch/powerpc
parentefa58fbf19fb778a8ad2fd000a6dfa9c75263a37 (diff)
downloadlinux-0be234a46596cd19eb56d2cf46836de8221afb6b.tar.xz
[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>
Diffstat (limited to 'arch/powerpc')
-rw-r--r--arch/powerpc/kernel/signal_64.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/arch/powerpc/kernel/signal_64.c b/arch/powerpc/kernel/signal_64.c
index faeb8f207ea4..da7c058e3731 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, &current->thread.fpr, FP_REGS_SIZE);
err |= __put_user(signr, &sc->signal);
err |= __put_user(handler, &sc->handler);