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Subject[PATCH v6 1/2] powerpc/syscall: Do not check unsupported scv vector on PPC32
Date
Only book3s/64 has scv. No need to check the 0x7ff0 trap on 32 or 64e.
For that, add a helper trap_is_unsupported_scv() similar to
trap_is_scv().

And ignore the scv parameter in syscall_exit_prepare (Save 14 cycles
346 => 332 cycles)

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
v5: Added a helper trap_is_unsupported_scv()
v6: Still set r5 when calling syscall_exit_prepare() and introduce a local bool 'is_not_scv'
---
arch/powerpc/include/asm/ptrace.h | 5 +++++
arch/powerpc/kernel/interrupt.c | 9 +++++----
2 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/include/asm/ptrace.h b/arch/powerpc/include/asm/ptrace.h
index 8236c5e749e4..975ba260006a 100644
--- a/arch/powerpc/include/asm/ptrace.h
+++ b/arch/powerpc/include/asm/ptrace.h
@@ -232,6 +232,11 @@ static inline bool trap_is_scv(struct pt_regs *regs)
return (IS_ENABLED(CONFIG_PPC_BOOK3S_64) && TRAP(regs) == 0x3000);
}

+static inline bool trap_is_unsupported_scv(struct pt_regs *regs)
+{
+ return IS_ENABLED(CONFIG_PPC_BOOK3S_64) && TRAP(regs) == 0x7ff0;
+}
+
static inline bool trap_is_syscall(struct pt_regs *regs)
{
return (trap_is_scv(regs) || TRAP(regs) == 0xc00);
diff --git a/arch/powerpc/kernel/interrupt.c b/arch/powerpc/kernel/interrupt.c
index 107ec39f05cb..75d657b63332 100644
--- a/arch/powerpc/kernel/interrupt.c
+++ b/arch/powerpc/kernel/interrupt.c
@@ -88,7 +88,7 @@ notrace long system_call_exception(long r3, long r4, long r5,
local_irq_enable();

if (unlikely(current_thread_info()->flags & _TIF_SYSCALL_DOTRACE)) {
- if (unlikely(regs->trap == 0x7ff0)) {
+ if (unlikely(trap_is_unsupported_scv(regs))) {
/* Unsupported scv vector */
_exception(SIGILL, regs, ILL_ILLOPC, regs->nip);
return regs->gpr[3];
@@ -111,7 +111,7 @@ notrace long system_call_exception(long r3, long r4, long r5,
r8 = regs->gpr[8];

} else if (unlikely(r0 >= NR_syscalls)) {
- if (unlikely(regs->trap == 0x7ff0)) {
+ if (unlikely(trap_is_unsupported_scv(regs))) {
/* Unsupported scv vector */
_exception(SIGILL, regs, ILL_ILLOPC, regs->nip);
return regs->gpr[3];
@@ -220,6 +220,7 @@ notrace unsigned long syscall_exit_prepare(unsigned long r3,
unsigned long *ti_flagsp = &current_thread_info()->flags;
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);

@@ -234,7 +235,7 @@ notrace unsigned long syscall_exit_prepare(unsigned long r3,

ti_flags = *ti_flagsp;

- if (unlikely(r3 >= (unsigned long)-MAX_ERRNO) && !scv) {
+ 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 */
@@ -305,7 +306,7 @@ notrace unsigned long syscall_exit_prepare(unsigned long r3,
user_enter_irqoff();

/* scv need not set RI=0 because SRRs are not used */
- if (unlikely(!__prep_irq_for_enabled_exit(!scv))) {
+ if (unlikely(!__prep_irq_for_enabled_exit(is_not_scv))) {
user_exit_irqoff();
local_irq_enable();
local_irq_disable();
--
2.25.0
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