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Message-Id: <cd0634769e5fea397411a0f833db52749852c6f8.1620980916.git.christophe.leroy@csgroup.eu>
Date: Fri, 14 May 2021 08:28:49 +0000 (UTC)
From: Christophe Leroy <christophe.leroy@...roup.eu>
To: Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Paul Mackerras <paulus@...ba.org>,
Michael Ellerman <mpe@...erman.id.au>, npiggin@...il.com
Cc: linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH 1/2] powerpc/interrupt: Refactor interrupt_exit_user_prepare()
and syscall_exit_prepare()
Last part of interrupt_exit_user_prepare() and syscall_exit_prepare()
are identical.
Create a __interrupt_exit_user_prepare() function that is called by
both.
Note that it replaces a local_irq_save(flags) by local_irq_disable().
This is similar because the flags are never used. On ppc 8xx it is
more efficient because it doesn't require reading MSR.
Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
---
It requires the following commits that are in powerpc/fixes-test:
5d510ed78bcf powerpc/syscall: Calling kuap_save_and_lock() is wrong
a78339698ab1 powerpc/interrupts: Fix kuep_unlock() call
Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
---
arch/powerpc/kernel/interrupt.c | 147 ++++++++++----------------------
1 file changed, 44 insertions(+), 103 deletions(-)
diff --git a/arch/powerpc/kernel/interrupt.c b/arch/powerpc/kernel/interrupt.c
index e0938ba298f2..d896fc6ed0be 100644
--- a/arch/powerpc/kernel/interrupt.c
+++ b/arch/powerpc/kernel/interrupt.c
@@ -231,56 +231,15 @@ static notrace void booke_load_dbcr0(void)
#endif
}
-/*
- * This should be called after a syscall returns, with r3 the return value
- * from the syscall. If this function returns non-zero, the system call
- * exit assembly should additionally load all GPR registers and CTR and XER
- * from the interrupt frame.
- *
- * The function graph tracer can not trace the return side of this function,
- * because RI=0 and soft mask state is "unreconciled", so it is marked notrace.
- */
-notrace unsigned long syscall_exit_prepare(unsigned long r3,
- struct pt_regs *regs,
- long scv)
+static notrace unsigned long __interrupt_exit_user_prepare(struct pt_regs *regs, unsigned long ret,
+ bool is_not_scv)
{
unsigned long ti_flags;
- unsigned long ret = 0;
- bool is_not_scv = !IS_ENABLED(CONFIG_PPC_BOOK3S_64) || !scv;
CT_WARN_ON(ct_state() == CONTEXT_USER);
kuap_assert_locked();
- regs->result = r3;
-
- /* Check whether the syscall is issued inside a restartable sequence */
- rseq_syscall(regs);
-
- ti_flags = current_thread_info()->flags;
-
- if (unlikely(r3 >= (unsigned long)-MAX_ERRNO) && is_not_scv) {
- if (likely(!(ti_flags & (_TIF_NOERROR | _TIF_RESTOREALL)))) {
- r3 = -r3;
- regs->ccr |= 0x10000000; /* Set SO bit in CR */
- }
- }
-
- if (unlikely(ti_flags & _TIF_PERSYSCALL_MASK)) {
- if (ti_flags & _TIF_RESTOREALL)
- ret = _TIF_RESTOREALL;
- else
- regs->gpr[3] = r3;
- clear_bits(_TIF_PERSYSCALL_MASK, ¤t_thread_info()->flags);
- } else {
- regs->gpr[3] = r3;
- }
-
- if (unlikely(ti_flags & _TIF_SYSCALL_DOTRACE)) {
- do_syscall_trace_leave(regs);
- ret |= _TIF_RESTOREALL;
- }
-
local_irq_disable();
again:
@@ -303,7 +262,7 @@ notrace unsigned long syscall_exit_prepare(unsigned long r3,
ti_flags = READ_ONCE(current_thread_info()->flags);
}
- if (IS_ENABLED(CONFIG_PPC_BOOK3S) && IS_ENABLED(CONFIG_PPC_FPU)) {
+ if (IS_ENABLED(CONFIG_PPC_BOOK3S_64) && IS_ENABLED(CONFIG_PPC_FPU)) {
if (IS_ENABLED(CONFIG_PPC_TRANSACTIONAL_MEM) &&
unlikely((ti_flags & _TIF_RESTORE_TM))) {
restore_tm_state(regs);
@@ -352,81 +311,63 @@ notrace unsigned long syscall_exit_prepare(unsigned long r3,
return ret;
}
-notrace unsigned long interrupt_exit_user_prepare(struct pt_regs *regs, unsigned long msr)
+/*
+ * This should be called after a syscall returns, with r3 the return value
+ * from the syscall. If this function returns non-zero, the system call
+ * exit assembly should additionally load all GPR registers and CTR and XER
+ * from the interrupt frame.
+ *
+ * The function graph tracer can not trace the return side of this function,
+ * because RI=0 and soft mask state is "unreconciled", so it is marked notrace.
+ */
+notrace unsigned long syscall_exit_prepare(unsigned long r3,
+ struct pt_regs *regs,
+ long scv)
{
unsigned long ti_flags;
- unsigned long flags;
unsigned long ret = 0;
+ bool is_not_scv = !IS_ENABLED(CONFIG_PPC_BOOK3S_64) || !scv;
- if (!IS_ENABLED(CONFIG_BOOKE) && !IS_ENABLED(CONFIG_40x))
- BUG_ON(!(regs->msr & MSR_RI));
- BUG_ON(!(regs->msr & MSR_PR));
- BUG_ON(arch_irq_disabled_regs(regs));
- CT_WARN_ON(ct_state() == CONTEXT_USER);
+ regs->result = r3;
- /*
- * We don't need to restore AMR on the way back to userspace for KUAP.
- * AMR can only have been unlocked if we interrupted the kernel.
- */
- kuap_assert_locked();
+ /* Check whether the syscall is issued inside a restartable sequence */
+ rseq_syscall(regs);
- local_irq_save(flags);
+ ti_flags = current_thread_info()->flags;
-again:
- ti_flags = READ_ONCE(current_thread_info()->flags);
- while (unlikely(ti_flags & (_TIF_USER_WORK_MASK & ~_TIF_RESTORE_TM))) {
- local_irq_enable(); /* returning to user: may enable */
- if (ti_flags & _TIF_NEED_RESCHED) {
- schedule();
- } else {
- if (ti_flags & _TIF_SIGPENDING)
- ret |= _TIF_RESTOREALL;
- do_notify_resume(regs, ti_flags);
+ if (unlikely(r3 >= (unsigned long)-MAX_ERRNO) && is_not_scv) {
+ if (likely(!(ti_flags & (_TIF_NOERROR | _TIF_RESTOREALL)))) {
+ r3 = -r3;
+ regs->ccr |= 0x10000000; /* Set SO bit in CR */
}
- local_irq_disable();
- ti_flags = READ_ONCE(current_thread_info()->flags);
}
- if (IS_ENABLED(CONFIG_PPC_BOOK3S_64) && IS_ENABLED(CONFIG_PPC_FPU)) {
- if (IS_ENABLED(CONFIG_PPC_TRANSACTIONAL_MEM) &&
- unlikely((ti_flags & _TIF_RESTORE_TM))) {
- restore_tm_state(regs);
- } else {
- unsigned long mathflags = MSR_FP;
-
- if (cpu_has_feature(CPU_FTR_VSX))
- mathflags |= MSR_VEC | MSR_VSX;
- else if (cpu_has_feature(CPU_FTR_ALTIVEC))
- mathflags |= MSR_VEC;
-
- /* See above restore_math comment */
- if ((regs->msr & mathflags) != mathflags)
- restore_math(regs);
- }
+ if (unlikely(ti_flags & _TIF_PERSYSCALL_MASK)) {
+ if (ti_flags & _TIF_RESTOREALL)
+ ret = _TIF_RESTOREALL;
+ else
+ regs->gpr[3] = r3;
+ clear_bits(_TIF_PERSYSCALL_MASK, ¤t_thread_info()->flags);
+ } else {
+ regs->gpr[3] = r3;
}
- user_enter_irqoff();
-
- if (unlikely(!__prep_irq_for_enabled_exit(true))) {
- user_exit_irqoff();
- local_irq_enable();
- local_irq_disable();
- goto again;
+ if (unlikely(ti_flags & _TIF_SYSCALL_DOTRACE)) {
+ do_syscall_trace_leave(regs);
+ ret |= _TIF_RESTOREALL;
}
- booke_load_dbcr0();
-
-#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
- local_paca->tm_scratch = regs->msr;
-#endif
-
- account_cpu_user_exit();
+ return __interrupt_exit_user_prepare(regs, ret, is_not_scv);
+}
- /* Restore user access locks last */
- kuap_user_restore(regs);
- kuep_unlock();
+notrace unsigned long interrupt_exit_user_prepare(struct pt_regs *regs, unsigned long msr)
+{
+ if (!IS_ENABLED(CONFIG_BOOKE) && !IS_ENABLED(CONFIG_40x))
+ BUG_ON(!(regs->msr & MSR_RI));
+ BUG_ON(!(regs->msr & MSR_PR));
+ BUG_ON(arch_irq_disabled_regs(regs));
- return ret;
+ return __interrupt_exit_user_prepare(regs, 0, true);
}
void preempt_schedule_irq(void);
--
2.25.0
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