[PATCH v5 17/22] powerpc/syscall: Do not check unsupported scv vector on PPC32

Christophe Leroy
2021-02-08T16:38:27Z

Only PPC64 has scv. No need to check the 0x7ff0 trap on PPC32.
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()
---
arch/powerpc/include/asm/ptrace.h | 5 +++++
arch/powerpc/kernel/entry_32.S | 1 -
arch/powerpc/kernel/interrupt.c | 7 +++++--
3 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/include/asm/ptrace.h b/arch/powerpc/include/asm/ptrace.h
index 58f9dc060a7b..2c842b11a924 100644
--- a/arch/powerpc/include/asm/ptrace.h
+++ b/arch/powerpc/include/asm/ptrace.h
@@ -229,6 +229,11 @@ 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/entry_32.S b/arch/powerpc/kernel/entry_32.S
index cffe58e63356..7c824e8928d0 100644
--- a/arch/powerpc/kernel/entry_32.S
+++ b/arch/powerpc/kernel/entry_32.S
@@ -344,7 +344,6 @@ transfer_to_syscall:

ret_from_syscall:
addi r4,r1,STACK_FRAME_OVERHEAD
- li r5,0
bl syscall_exit_prepare
#if defined(CONFIG_4xx) || defined(CONFIG_BOOKE)
/* If the process has its own DBCR0 value, load it up. The internal
diff --git a/arch/powerpc/kernel/interrupt.c b/arch/powerpc/kernel/interrupt.c
index 205902052112..8fafca727b8b 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];
@@ -224,6 +224,9 @@ notrace unsigned long syscall_exit_prepare(unsigned long r3,
unsigned long ti_flags;
unsigned long ret = 0;

+ if (IS_ENABLED(CONFIG_PPC32))
+ scv = 0;
+
CT_WARN_ON(ct_state() == CONTEXT_USER);

#ifdef CONFIG_PPC64
--
2.25.0