This series implements C syscall entry/exit for PPC32. It reuses
the work already done for PPC64.
This series is based on today's next-test (f538b53fd47a) where main patchs from v5 are merged in.
The first patch is important for performance.
v6:
- Forced scv param to 0 on syscall_exit_prepare(), and added is_not_scv bool.
- Reworked the last patch to avoid code duplication.
Christophe Leroy (2):
powerpc/syscall: Do not check unsupported scv vector on PPC32
powerpc/32: Handle bookE debugging in C in syscall entry/exit
arch/powerpc/include/asm/interrupt.h | 12 +++++++
arch/powerpc/include/asm/ptrace.h | 5 +++
arch/powerpc/include/asm/reg_booke.h | 3 ++
arch/powerpc/kernel/entry_32.S | 7 ----
arch/powerpc/kernel/head_32.h | 15 ---------
arch/powerpc/kernel/head_booke.h | 19 -----------
arch/powerpc/kernel/interrupt.c | 50 ++++++++++++++++++----------
7 files changed, 52 insertions(+), 59 deletions(-)
--
2.25.0
By saving the pointer pointing to thread_info.flags, gcc copies r2
in a non-volatile register.
We know 'current' doesn't change, so avoid that intermediaite pointer.
Reduces null_syscall benchmark by 2 cycles (322 => 320 cycles)
On PPC64, gcc seems to know that 'current' is not changing, and it keeps
it in a non volatile register to avoid multiple read of 'current' in paca.
Signed-off-by: Christophe Leroy <[email protected]>
---
v5: Also in interrupt exit prepare
v6: Removed change related to booke current->thread.debug
v7: Rebased on top of "powerpc/32: Handle bookE debugging in C in syscall entry/exit"
---
arch/powerpc/kernel/interrupt.c | 21 +++++++++------------
1 file changed, 9 insertions(+), 12 deletions(-)
diff --git a/arch/powerpc/kernel/interrupt.c b/arch/powerpc/kernel/interrupt.c
index f93664ad4a5e..398cd86b6ada 100644
--- a/arch/powerpc/kernel/interrupt.c
+++ b/arch/powerpc/kernel/interrupt.c
@@ -241,7 +241,6 @@ notrace unsigned long syscall_exit_prepare(unsigned long r3,
struct pt_regs *regs,
long scv)
{
- unsigned long *ti_flagsp = ¤t_thread_info()->flags;
unsigned long ti_flags;
unsigned long ret = 0;
bool is_not_scv = !IS_ENABLED(CONFIG_PPC_BOOK3S_64) || !scv;
@@ -257,7 +256,7 @@ notrace unsigned long syscall_exit_prepare(unsigned long r3,
/* Check whether the syscall is issued inside a restartable sequence */
rseq_syscall(regs);
- ti_flags = *ti_flagsp;
+ ti_flags = current_thread_info()->flags;
if (unlikely(r3 >= (unsigned long)-MAX_ERRNO) && is_not_scv) {
if (likely(!(ti_flags & (_TIF_NOERROR | _TIF_RESTOREALL)))) {
@@ -271,7 +270,7 @@ notrace unsigned long syscall_exit_prepare(unsigned long r3,
ret = _TIF_RESTOREALL;
else
regs->gpr[3] = r3;
- clear_bits(_TIF_PERSYSCALL_MASK, ti_flagsp);
+ clear_bits(_TIF_PERSYSCALL_MASK, ¤t_thread_info()->flags);
} else {
regs->gpr[3] = r3;
}
@@ -284,7 +283,7 @@ notrace unsigned long syscall_exit_prepare(unsigned long r3,
local_irq_disable();
again:
- ti_flags = READ_ONCE(*ti_flagsp);
+ ti_flags = READ_ONCE(current_thread_info()->flags);
while (unlikely(ti_flags & (_TIF_USER_WORK_MASK & ~_TIF_RESTORE_TM))) {
local_irq_enable();
if (ti_flags & _TIF_NEED_RESCHED) {
@@ -300,7 +299,7 @@ notrace unsigned long syscall_exit_prepare(unsigned long r3,
do_notify_resume(regs, ti_flags);
}
local_irq_disable();
- ti_flags = READ_ONCE(*ti_flagsp);
+ ti_flags = READ_ONCE(current_thread_info()->flags);
}
if (IS_ENABLED(CONFIG_PPC_BOOK3S) && IS_ENABLED(CONFIG_PPC_FPU)) {
@@ -357,7 +356,6 @@ notrace unsigned long syscall_exit_prepare(unsigned long r3,
#ifndef CONFIG_PPC_BOOK3E_64 /* BOOK3E not yet using this */
notrace unsigned long interrupt_exit_user_prepare(struct pt_regs *regs, unsigned long msr)
{
- unsigned long *ti_flagsp = ¤t_thread_info()->flags;
unsigned long ti_flags;
unsigned long flags;
unsigned long ret = 0;
@@ -380,7 +378,7 @@ notrace unsigned long interrupt_exit_user_prepare(struct pt_regs *regs, unsigned
local_irq_save(flags);
again:
- ti_flags = READ_ONCE(*ti_flagsp);
+ 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) {
@@ -391,7 +389,7 @@ notrace unsigned long interrupt_exit_user_prepare(struct pt_regs *regs, unsigned
do_notify_resume(regs, ti_flags);
}
local_irq_disable();
- ti_flags = READ_ONCE(*ti_flagsp);
+ ti_flags = READ_ONCE(current_thread_info()->flags);
}
if (IS_ENABLED(CONFIG_PPC_BOOK3S) && IS_ENABLED(CONFIG_PPC_FPU)) {
@@ -443,7 +441,6 @@ void preempt_schedule_irq(void);
notrace unsigned long interrupt_exit_kernel_prepare(struct pt_regs *regs, unsigned long msr)
{
- unsigned long *ti_flagsp = ¤t_thread_info()->flags;
unsigned long flags;
unsigned long ret = 0;
#ifdef CONFIG_PPC64
@@ -466,8 +463,8 @@ notrace unsigned long interrupt_exit_kernel_prepare(struct pt_regs *regs, unsign
amr = kuap_get_and_check_amr();
#endif
- if (unlikely(*ti_flagsp & _TIF_EMULATE_STACK_STORE)) {
- clear_bits(_TIF_EMULATE_STACK_STORE, ti_flagsp);
+ if (unlikely(current_thread_info()->flags & _TIF_EMULATE_STACK_STORE)) {
+ clear_bits(_TIF_EMULATE_STACK_STORE, ¤t_thread_info()->flags);
ret = 1;
}
@@ -479,7 +476,7 @@ notrace unsigned long interrupt_exit_kernel_prepare(struct pt_regs *regs, unsign
again:
if (IS_ENABLED(CONFIG_PREEMPT)) {
/* Return to preemptible kernel context */
- if (unlikely(*ti_flagsp & _TIF_NEED_RESCHED)) {
+ if (unlikely(current_thread_info()->flags & _TIF_NEED_RESCHED)) {
if (preempt_count() == 0)
preempt_schedule_irq();
}
--
2.25.0
On Tue, 9 Feb 2021 19:29:26 +0000 (UTC), Christophe Leroy wrote:
> This series implements C syscall entry/exit for PPC32. It reuses
> the work already done for PPC64.
>
> This series is based on today's next-test (f538b53fd47a) where main patchs from v5 are merged in.
>
> The first patch is important for performance.
>
> [...]
Applied to powerpc/next.
[1/3] powerpc/syscall: Do not check unsupported scv vector on PPC32
https://git.kernel.org/powerpc/c/b966f2279048ee9f30d83ef8568b99fa40917c54
[2/3] powerpc/32: Handle bookE debugging in C in syscall entry/exit
https://git.kernel.org/powerpc/c/d524dda719f06967db4d3ba519edf9267f84c155
[3/3] powerpc/syscall: Avoid storing 'current' in another pointer
https://git.kernel.org/powerpc/c/5b90b9661a3396e00f6e8bcbb617a0787fb683d0
cheers