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authorPaul Mackerras <paulus@samba.org>2006-06-07 16:14:40 +1000
committerPaul Mackerras <paulus@samba.org>2006-06-09 21:24:15 +1000
commitfab5db97e44f76461f76b24adfa8ccb14d4df498 (patch)
tree123026a1a6f1702468220189b7410077479ae8a2 /arch/powerpc/kernel/signal_64.c
parent651d765d0b2c72d33430487c8b6ef64c60cd2134 (diff)
[PATCH] powerpc: Implement support for setting little-endian mode via prctl
This adds the PowerPC part of the code to allow processes to change their endian mode via prctl. This also extends the alignment exception handler to be able to fix up alignment exceptions that occur in little-endian mode, both for "PowerPC" little-endian and true little-endian. We always enter signal handlers in big-endian mode -- the support for little-endian mode does not amount to the creation of a little-endian user/kernel ABI. If the signal handler returns, the endian mode is restored to what it was when the signal was delivered. We have two new kernel CPU feature bits, one for PPC little-endian and one for true little-endian. Most of the classic 32-bit processors support PPC little-endian, and this is reflected in the CPU feature table. There are two corresponding feature bits reported to userland in the AT_HWCAP aux vector entry. This is based on an earlier patch by Anton Blanchard. Signed-off-by: Paul Mackerras <paulus@samba.org>
Diffstat (limited to 'arch/powerpc/kernel/signal_64.c')
-rw-r--r--arch/powerpc/kernel/signal_64.c12
1 files changed, 8 insertions, 4 deletions
diff --git a/arch/powerpc/kernel/signal_64.c b/arch/powerpc/kernel/signal_64.c
index 23ba69c26913..66a5fbe31989 100644
--- a/arch/powerpc/kernel/signal_64.c
+++ b/arch/powerpc/kernel/signal_64.c
@@ -141,9 +141,7 @@ static long restore_sigcontext(struct pt_regs *regs, sigset_t *set, int sig,
unsigned long err = 0;
unsigned long save_r13 = 0;
elf_greg_t *gregs = (elf_greg_t *)regs;
-#ifdef CONFIG_ALTIVEC
unsigned long msr;
-#endif
int i;
/* If this is not a signal return, we preserve the TLS in r13 */
@@ -154,7 +152,12 @@ static long restore_sigcontext(struct pt_regs *regs, sigset_t *set, int sig,
err |= __copy_from_user(regs, &sc->gp_regs,
PT_MSR*sizeof(unsigned long));
- /* skip MSR and SOFTE */
+ /* get MSR separately, transfer the LE bit if doing signal return */
+ err |= __get_user(msr, &sc->gp_regs[PT_MSR]);
+ if (sig)
+ regs->msr = (regs->msr & ~MSR_LE) | (msr & MSR_LE);
+
+ /* skip SOFTE */
for (i = PT_MSR+1; i <= PT_RESULT; i++) {
if (i == PT_SOFTE)
continue;
@@ -179,7 +182,6 @@ static long restore_sigcontext(struct pt_regs *regs, sigset_t *set, int sig,
#ifdef CONFIG_ALTIVEC
err |= __get_user(v_regs, &sc->v_regs);
- err |= __get_user(msr, &sc->gp_regs[PT_MSR]);
if (err)
return err;
/* Copy 33 vec registers (vr0..31 and vscr) from the stack */
@@ -410,6 +412,8 @@ static int setup_rt_frame(int signr, struct k_sigaction *ka, siginfo_t *info,
/* Set up "regs" so we "return" to the signal handler. */
err |= get_user(regs->nip, &funct_desc_ptr->entry);
+ /* enter the signal handler in big-endian mode */
+ regs->msr &= ~MSR_LE;
regs->gpr[1] = newsp;
err |= get_user(regs->gpr[2], &funct_desc_ptr->toc);
regs->gpr[3] = signr;