[PATCH v6 1/2] powerpc/syscall: Do not check unsupported scv vector on PPC32

[Christophe Leroy]

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.le...@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