* [PATCH v6 1/2] powerpc/syscall: Do not check unsupported scv vector on PPC32
2021-02-09 19:29 [PATCH v6 0/2] powerpc/32: Implement C syscall entry/exit (complement) Christophe Leroy
@ 2021-02-09 19:29 ` Christophe Leroy
2021-02-09 19:29 ` [PATCH v6 2/2] powerpc/32: Handle bookE debugging in C in syscall entry/exit Christophe Leroy
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: Christophe Leroy @ 2021-02-09 19:29 UTC (permalink / raw)
To: Benjamin Herrenschmidt, Paul Mackerras, Michael Ellerman,
npiggin, msuchanek
Cc: linux-kernel, linuxppc-dev
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 = ¤t_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
^ permalink raw reply related [flat|nested] 5+ messages in thread
* [PATCH v6 2/2] powerpc/32: Handle bookE debugging in C in syscall entry/exit
2021-02-09 19:29 [PATCH v6 0/2] powerpc/32: Implement C syscall entry/exit (complement) Christophe Leroy
2021-02-09 19:29 ` [PATCH v6 1/2] powerpc/syscall: Do not check unsupported scv vector on PPC32 Christophe Leroy
@ 2021-02-09 19:29 ` Christophe Leroy
2021-02-10 8:44 ` [PATCH v6 3/2] powerpc/syscall: Avoid storing 'current' in another pointer Christophe Leroy
2021-02-12 0:19 ` [PATCH v6 0/2] powerpc/32: Implement C syscall entry/exit (complement) Michael Ellerman
3 siblings, 0 replies; 5+ messages in thread
From: Christophe Leroy @ 2021-02-09 19:29 UTC (permalink / raw)
To: Benjamin Herrenschmidt, Paul Mackerras, Michael Ellerman,
npiggin, msuchanek
Cc: linux-kernel, linuxppc-dev
The handling of SPRN_DBCR0 and other registers can easily
be done in C instead of ASM.
For that, create booke_load_dbcr0() and booke_restore_dbcr0().
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
v5: New
v6: Refactor into helpers
---
arch/powerpc/include/asm/interrupt.h | 12 ++++++++
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 | 41 ++++++++++++++++++----------
6 files changed, 42 insertions(+), 55 deletions(-)
diff --git a/arch/powerpc/include/asm/interrupt.h b/arch/powerpc/include/asm/interrupt.h
index 4badb3e51c19..e62c37915bbe 100644
--- a/arch/powerpc/include/asm/interrupt.h
+++ b/arch/powerpc/include/asm/interrupt.h
@@ -14,6 +14,18 @@ struct interrupt_state {
#endif
};
+static inline void booke_restore_dbcr0(void)
+{
+#ifdef CONFIG_PPC_ADV_DEBUG_REGS
+ unsigned long dbcr0 = current->thread.debug.dbcr0;
+
+ if (IS_ENABLED(CONFIG_PPC32) && unlikely(dbcr0 & DBCR0_IDM)) {
+ mtspr(SPRN_DBSR, -1);
+ mtspr(SPRN_DBCR0, global_dbcr0[smp_processor_id()]);
+ }
+#endif
+}
+
static inline void interrupt_enter_prepare(struct pt_regs *regs, struct interrupt_state *state)
{
/*
diff --git a/arch/powerpc/include/asm/reg_booke.h b/arch/powerpc/include/asm/reg_booke.h
index 262782f08fd4..17b8dcd9a40d 100644
--- a/arch/powerpc/include/asm/reg_booke.h
+++ b/arch/powerpc/include/asm/reg_booke.h
@@ -691,6 +691,9 @@
#define mttmr(rn, v) asm volatile(MTTMR(rn, %0) : \
: "r" ((unsigned long)(v)) \
: "memory")
+
+extern unsigned long global_dbcr0[];
+
#endif /* !__ASSEMBLY__ */
#endif /* __ASM_POWERPC_REG_BOOKE_H__ */
diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
index 9dd90be9f8a5..78c430b7f9d9 100644
--- a/arch/powerpc/kernel/entry_32.S
+++ b/arch/powerpc/kernel/entry_32.S
@@ -343,13 +343,6 @@ 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
- debug mode bit tells us that dbcr0 should be loaded. */
- lwz r0,THREAD+THREAD_DBCR0(r2)
- andis. r10,r0,DBCR0_IDM@h
- bnel- load_dbcr0
-#endif
#ifdef CONFIG_PPC_47x
lis r4,icache_44x_need_flush@ha
lwz r5,icache_44x_need_flush@l(r4)
diff --git a/arch/powerpc/kernel/head_32.h b/arch/powerpc/kernel/head_32.h
index 1afad7bc3395..5d4706c14572 100644
--- a/arch/powerpc/kernel/head_32.h
+++ b/arch/powerpc/kernel/head_32.h
@@ -153,21 +153,6 @@
SAVE_4GPRS(3, r11)
SAVE_2GPRS(7, r11)
addi r2,r12,-THREAD
-#if defined(CONFIG_40x)
- /* Check to see if the dbcr0 register is set up to debug. Use the
- internal debug mode bit to do this. */
- lwz r12,THREAD_DBCR0(r12)
- andis. r12,r12,DBCR0_IDM@h
- beq+ 3f
- /* From user and task is ptraced - load up global dbcr0 */
- li r12,-1 /* clear all pending debug events */
- mtspr SPRN_DBSR,r12
- lis r11,global_dbcr0@ha
- addi r11,r11,global_dbcr0@l
- lwz r12,0(r11)
- mtspr SPRN_DBCR0,r12
-3:
-#endif
b transfer_to_syscall /* jump to handler */
.endm
diff --git a/arch/powerpc/kernel/head_booke.h b/arch/powerpc/kernel/head_booke.h
index 5f565232b99d..47857795f50a 100644
--- a/arch/powerpc/kernel/head_booke.h
+++ b/arch/powerpc/kernel/head_booke.h
@@ -130,25 +130,6 @@ ALT_FTR_SECTION_END_IFSET(CPU_FTR_EMB_HV)
SAVE_2GPRS(7, r11)
addi r2,r10,-THREAD
- /* Check to see if the dbcr0 register is set up to debug. Use the
- internal debug mode bit to do this. */
- lwz r12,THREAD_DBCR0(r10)
- andis. r12,r12,DBCR0_IDM@h
- beq+ 3f
- /* From user and task is ptraced - load up global dbcr0 */
- li r12,-1 /* clear all pending debug events */
- mtspr SPRN_DBSR,r12
- lis r11,global_dbcr0@ha
- addi r11,r11,global_dbcr0@l
-#ifdef CONFIG_SMP
- lwz r10, TASK_CPU(r2)
- slwi r10, r10, 2
- add r11, r11, r10
-#endif
- lwz r12,0(r11)
- mtspr SPRN_DBCR0,r12
-
-3:
b transfer_to_syscall /* jump to handler */
.endm
diff --git a/arch/powerpc/kernel/interrupt.c b/arch/powerpc/kernel/interrupt.c
index 75d657b63332..f93664ad4a5e 100644
--- a/arch/powerpc/kernel/interrupt.c
+++ b/arch/powerpc/kernel/interrupt.c
@@ -73,6 +73,8 @@ notrace long system_call_exception(long r3, long r4, long r5,
kuap_check_amr();
#endif
+ booke_restore_dbcr0();
+
account_cpu_user_entry();
account_stolen_time();
@@ -204,6 +206,28 @@ static notrace inline bool prep_irq_for_enabled_exit(bool clear_ri, bool irqs_en
return false;
}
+static notrace void booke_load_dbcr0(void)
+{
+#ifdef CONFIG_PPC_ADV_DEBUG_REGS
+ unsigned long dbcr0 = current->thread.debug.dbcr0;
+
+ if (likely(!(dbcr0 & DBCR0_IDM)))
+ return;
+
+ /*
+ * Check to see if the dbcr0 register is set up to debug.
+ * Use the internal debug mode bit to do this.
+ */
+ mtmsr(mfmsr() & ~MSR_DE);
+ if (IS_ENABLED(CONFIG_PPC32)) {
+ isync();
+ global_dbcr0[smp_processor_id()] = mfspr(SPRN_DBCR0);
+ }
+ mtspr(SPRN_DBCR0, dbcr0);
+ mtspr(SPRN_DBSR, -1);
+#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
@@ -317,6 +341,8 @@ notrace unsigned long syscall_exit_prepare(unsigned long r3,
local_paca->tm_scratch = regs->msr;
#endif
+ booke_load_dbcr0();
+
account_cpu_user_exit();
#ifdef CONFIG_PPC_BOOK3S_64 /* BOOK3E and ppc32 not using this */
@@ -331,9 +357,6 @@ 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)
{
-#ifdef CONFIG_PPC_BOOK3E
- struct thread_struct *ts = ¤t->thread;
-#endif
unsigned long *ti_flagsp = ¤t_thread_info()->flags;
unsigned long ti_flags;
unsigned long flags;
@@ -398,17 +421,7 @@ notrace unsigned long interrupt_exit_user_prepare(struct pt_regs *regs, unsigned
goto again;
}
-#ifdef CONFIG_PPC_BOOK3E
- if (unlikely(ts->debug.dbcr0 & DBCR0_IDM)) {
- /*
- * Check to see if the dbcr0 register is set up to debug.
- * Use the internal debug mode bit to do this.
- */
- mtmsr(mfmsr() & ~MSR_DE);
- mtspr(SPRN_DBCR0, ts->debug.dbcr0);
- mtspr(SPRN_DBSR, -1);
- }
-#endif
+ booke_load_dbcr0();
#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
local_paca->tm_scratch = regs->msr;
--
2.25.0
^ permalink raw reply related [flat|nested] 5+ messages in thread
* [PATCH v6 3/2] powerpc/syscall: Avoid storing 'current' in another pointer
2021-02-09 19:29 [PATCH v6 0/2] powerpc/32: Implement C syscall entry/exit (complement) Christophe Leroy
2021-02-09 19:29 ` [PATCH v6 1/2] powerpc/syscall: Do not check unsupported scv vector on PPC32 Christophe Leroy
2021-02-09 19:29 ` [PATCH v6 2/2] powerpc/32: Handle bookE debugging in C in syscall entry/exit Christophe Leroy
@ 2021-02-10 8:44 ` Christophe Leroy
2021-02-12 0:19 ` [PATCH v6 0/2] powerpc/32: Implement C syscall entry/exit (complement) Michael Ellerman
3 siblings, 0 replies; 5+ messages in thread
From: Christophe Leroy @ 2021-02-10 8:44 UTC (permalink / raw)
To: Benjamin Herrenschmidt, Paul Mackerras, Michael Ellerman,
npiggin, msuchanek
Cc: linux-kernel, linuxppc-dev
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 <christophe.leroy@csgroup.eu>
---
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
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH v6 0/2] powerpc/32: Implement C syscall entry/exit (complement)
2021-02-09 19:29 [PATCH v6 0/2] powerpc/32: Implement C syscall entry/exit (complement) Christophe Leroy
` (2 preceding siblings ...)
2021-02-10 8:44 ` [PATCH v6 3/2] powerpc/syscall: Avoid storing 'current' in another pointer Christophe Leroy
@ 2021-02-12 0:19 ` Michael Ellerman
3 siblings, 0 replies; 5+ messages in thread
From: Michael Ellerman @ 2021-02-12 0:19 UTC (permalink / raw)
To: Paul Mackerras, msuchanek, Michael Ellerman, npiggin,
Benjamin Herrenschmidt, Christophe Leroy
Cc: linux-kernel, linuxppc-dev
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
^ permalink raw reply [flat|nested] 5+ messages in thread