[PATCH 1/2] powerpc/signal: Fix handling of SA_RESTORER sigaction flag

Christophe Leroy
2021-06-25T10:49:55Z

powerpc advertises support of SA_RESTORER sigaction flag.

Make it the truth.

Cc: stable@vger.kernel.org
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
arch/powerpc/kernel/signal_32.c | 8 ++++++--
arch/powerpc/kernel/signal_64.c | 4 +++-
2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/kernel/signal_32.c b/arch/powerpc/kernel/signal_32.c
index 0608581967f0..cf3da1386595 100644
--- a/arch/powerpc/kernel/signal_32.c
+++ b/arch/powerpc/kernel/signal_32.c
@@ -769,7 +769,9 @@ int handle_rt_signal32(struct ksignal *ksig, sigset_t *oldset,
}

/* Save user registers on the stack */
- if (tsk->mm->context.vdso) {
+ if (ksig->ka.sa.sa_flags & SA_RESTORER) {
+ tramp = (unsigned long)ksig->ka.sa.sa_restorer;
+ } else if (tsk->mm->context.vdso) {
tramp = VDSO32_SYMBOL(tsk->mm->context.vdso, sigtramp_rt32);
} else {
tramp = (unsigned long)mctx->mc_pad;
@@ -865,7 +867,9 @@ int handle_signal32(struct ksignal *ksig, sigset_t *oldset,
else
unsafe_save_user_regs(regs, mctx, tm_mctx, 1, failed);

- if (tsk->mm->context.vdso) {
+ if (ksig->ka.sa.sa_flags & SA_RESTORER) {
+ tramp = (unsigned long)ksig->ka.sa.sa_restorer;
+ } else if (tsk->mm->context.vdso) {
tramp = VDSO32_SYMBOL(tsk->mm->context.vdso, sigtramp32);
} else {
tramp = (unsigned long)mctx->mc_pad;
diff --git a/arch/powerpc/kernel/signal_64.c b/arch/powerpc/kernel/signal_64.c
index 1831bba0582e..fb31a334aca6 100644
--- a/arch/powerpc/kernel/signal_64.c
+++ b/arch/powerpc/kernel/signal_64.c
@@ -910,7 +910,9 @@ int handle_rt_signal64(struct ksignal *ksig, sigset_t *set,
tsk->thread.fp_state.fpscr = 0;

/* Set up to return from userspace. */
- if (tsk->mm->context.vdso) {
+ if (ksig->ka.sa.sa_flags & SA_RESTORER) {
+ regs_set_return_ip(regs, (unsigned long)ksig->ka.sa.sa_restorer);
+ } else if (tsk->mm->context.vdso) {
regs_set_return_ip(regs, VDSO64_SYMBOL(tsk->mm->context.vdso, sigtramp_rt64));
} else {
err |= setup_trampoline(__NR_rt_sigreturn, &frame->tramp[0]);
--
2.25.0