[PATCH v2 5/8] powerpc/signal: Include the new stack frame inside the user access block
From: "Christophe Leroy (CS GROUP)" <chleroy@kernel.org>
Date: 2026-06-02 08:47:27
Also in:
lkml
Subsystem:
linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Madhavan Srinivasan, Michael Ellerman, Linus Torvalds
Include the new stack frame inside the user access block and set it up using unsafe_put_user(). On an mpc 8321 (book3s/32) the improvment is about 4% on a process sending a signal to itself. Signed-off-by: Christophe Leroy (CS GROUP) <chleroy@kernel.org> --- arch/powerpc/kernel/signal_32.c | 28 ++++++++++++---------------- arch/powerpc/kernel/signal_64.c | 13 ++++++------- 2 files changed, 18 insertions(+), 23 deletions(-)
diff --git a/arch/powerpc/kernel/signal_32.c b/arch/powerpc/kernel/signal_32.c
index f5d5139a1426..6b1fbd95b07d 100644
--- a/arch/powerpc/kernel/signal_32.c
+++ b/arch/powerpc/kernel/signal_32.c@@ -730,7 +730,7 @@ int handle_rt_signal32(struct ksignal *ksig, sigset_t *oldset, struct task_struct *tsk) { struct rt_sigframe __user *frame; - unsigned long newsp = 0; + unsigned long __user *newsp; unsigned long tramp; struct pt_regs *regs = tsk->thread.regs; /* Save the thread's msr before get_tm_stackpointer() changes it */
@@ -738,12 +738,13 @@ int handle_rt_signal32(struct ksignal *ksig, sigset_t *oldset, /* Set up Signal Frame */ frame = get_sigframe(ksig, tsk, sizeof(*frame), 1); + newsp = (unsigned long __user *)((unsigned long)frame - (__SIGNAL_FRAMESIZE + 16)); if (MSR_TM_ACTIVE(msr)) prepare_save_tm_user_regs(); else prepare_save_user_regs(1); - scoped_user_rw_access(frame, badframe) { + scoped_user_rw_access_size(newsp, __SIGNAL_FRAMESIZE + 16 + sizeof(*frame), badframe) { struct mcontext __user *mctx; struct mcontext __user *tm_mctx = NULL;
@@ -784,6 +785,9 @@ int handle_rt_signal32(struct ksignal *ksig, sigset_t *oldset, asm("dcbst %y0; sync; icbi %y0; sync" :: "Z" (mctx->mc_pad[0])); } unsafe_put_sigset_t(&frame->uc.uc_sigmask, oldset, badframe); + + /* create a stack frame for the caller of the handler */ + unsafe_put_user(regs->gpr[1], newsp, badframe); } if (copy_siginfo_to_user(&frame->info, &ksig->info))
@@ -795,13 +799,8 @@ int handle_rt_signal32(struct ksignal *ksig, sigset_t *oldset, tsk->thread.fp_state.fpscr = 0; /* turn off all fp exceptions */ #endif - /* create a stack frame for the caller of the handler */ - newsp = ((unsigned long)frame) - (__SIGNAL_FRAMESIZE + 16); - if (put_user(regs->gpr[1], (u32 __user *)newsp)) - goto badframe; - /* Fill registers for signal handler */ - regs->gpr[1] = newsp; + regs->gpr[1] = (unsigned long)newsp; regs->gpr[3] = ksig->sig; regs->gpr[4] = (unsigned long)&frame->info; regs->gpr[5] = (unsigned long)&frame->uc;
@@ -826,7 +825,7 @@ int handle_signal32(struct ksignal *ksig, sigset_t *oldset, { struct sigcontext __user *sc; struct sigframe __user *frame; - unsigned long newsp = 0; + unsigned long __user *newsp; unsigned long tramp; struct pt_regs *regs = tsk->thread.regs; /* Save the thread's msr before get_tm_stackpointer() changes it */
@@ -834,12 +833,13 @@ int handle_signal32(struct ksignal *ksig, sigset_t *oldset, /* Set up Signal Frame */ frame = get_sigframe(ksig, tsk, sizeof(*frame), 1); + newsp = (unsigned long __user *)((unsigned long)frame - __SIGNAL_FRAMESIZE); if (MSR_TM_ACTIVE(msr)) prepare_save_tm_user_regs(); else prepare_save_user_regs(1); - scoped_user_rw_access(frame, badframe) { + scoped_user_rw_access_size(newsp, __SIGNAL_FRAMESIZE + sizeof(*frame), badframe) { struct mcontext __user *mctx; struct mcontext __user *tm_mctx = NULL;
@@ -876,6 +876,7 @@ int handle_signal32(struct ksignal *ksig, sigset_t *oldset, unsafe_put_user(PPC_RAW_SC(), &mctx->mc_pad[1], badframe); asm("dcbst %y0; sync; icbi %y0; sync" :: "Z" (mctx->mc_pad[0])); } + unsafe_put_user(regs->gpr[1], newsp, badframe); } regs->link = tramp;
@@ -884,12 +885,7 @@ int handle_signal32(struct ksignal *ksig, sigset_t *oldset, tsk->thread.fp_state.fpscr = 0; /* turn off all fp exceptions */ #endif - /* create a stack frame for the caller of the handler */ - newsp = ((unsigned long)frame) - __SIGNAL_FRAMESIZE; - if (put_user(regs->gpr[1], (u32 __user *)newsp)) - goto badframe; - - regs->gpr[1] = newsp; + regs->gpr[1] = (unsigned long)newsp; regs->gpr[3] = ksig->sig; regs->gpr[4] = (unsigned long) sc; regs_set_return_ip(regs, (unsigned long) ksig->ka.sa.sa_handler);
diff --git a/arch/powerpc/kernel/signal_64.c b/arch/powerpc/kernel/signal_64.c
index d23a980b32a8..19f320218ed1 100644
--- a/arch/powerpc/kernel/signal_64.c
+++ b/arch/powerpc/kernel/signal_64.c@@ -856,13 +856,14 @@ int handle_rt_signal64(struct ksignal *ksig, sigset_t *set, struct task_struct *tsk) { struct rt_sigframe __user *frame; - unsigned long newsp = 0; + unsigned long __user *newsp; long err = 0; struct pt_regs *regs = tsk->thread.regs; /* Save the thread's msr before get_tm_stackpointer() changes it */ unsigned long msr = regs->msr; frame = get_sigframe(ksig, tsk, sizeof(*frame), 0); + newsp = (unsigned long __user *)((unsigned long)frame - __SIGNAL_FRAMESIZE); /* * This only applies when calling unsafe_setup_sigcontext() and must be
@@ -874,7 +875,7 @@ int handle_rt_signal64(struct ksignal *ksig, sigset_t *set, err |= setup_tm_sigcontexts(frame, tsk, ksig->sig, NULL, (unsigned long)ksig->ka.sa.sa_handler, msr); - scoped_user_write_access(frame, badframe) { + scoped_user_write_access_size(newsp, __SIGNAL_FRAMESIZE + sizeof(*frame), badframe) { unsafe_put_user(&frame->info, &frame->pinfo, badframe); unsafe_put_user(&frame->uc, &frame->puc, badframe);
@@ -896,6 +897,8 @@ int handle_rt_signal64(struct ksignal *ksig, sigset_t *set, } unsafe_copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set), badframe); + /* Allocate a dummy caller frame for the signal handler. */ + unsafe_put_user(regs->gpr[1], newsp, badframe); } /* Save the siginfo outside of the unsafe block. */
@@ -915,10 +918,6 @@ int handle_rt_signal64(struct ksignal *ksig, sigset_t *set, regs_set_return_ip(regs, (unsigned long) &frame->tramp[0]); } - /* Allocate a dummy caller frame for the signal handler. */ - newsp = ((unsigned long)frame) - __SIGNAL_FRAMESIZE; - err |= put_user(regs->gpr[1], (unsigned long __user *)newsp); - /* Set up "regs" so we "return" to the signal handler. */ if (is_elf2_task()) { regs->ctr = (unsigned long) ksig->ka.sa.sa_handler;
@@ -940,7 +939,7 @@ int handle_rt_signal64(struct ksignal *ksig, sigset_t *set, /* enter the signal handler in native-endian mode */ regs_set_return_msr(regs, (regs->msr & ~MSR_LE) | (MSR_KERNEL & MSR_LE)); - regs->gpr[1] = newsp; + regs->gpr[1] = (unsigned long)newsp; regs->gpr[3] = ksig->sig; regs->result = 0; if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
--
2.54.0