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Commit 6f76a011 authored by Christophe Leroy's avatar Christophe Leroy Committed by Michael Ellerman
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powerpc/syscall: implement system call entry/exit logic in C for PPC32 

That's port of PPC64 syscall entry/exit logic in C to PPC32.

Performancewise on 8xx:
Before : 304 cycles on null_syscall
After  : 348 cycles on null_syscall
Signed-off-by: default avatarChristophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/a93b08e1275e9d1f0b1c39043d1b827586b2b401.1612796617.git.christophe.leroy@csgroup.eu
parent fbcee2eb
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Showing with 30 additions and 229 deletions
arch/powerpc/kernel/entry_32.S
View file @ 6f76a011
......@@ -329,117 +329,23 @@ stack_ovf:
_ASM_NOKPROBE_SYMBOL(stack_ovf)
#endif
#ifdef CONFIG_TRACE_IRQFLAGS
trace_syscall_entry_irq_off:
/*
* Syscall shouldn't happen while interrupts are disabled,
* so let's do a warning here.
*/
0: trap
EMIT_BUG_ENTRY 0b,__FILE__,__LINE__, BUGFLAG_WARNING
bl trace_hardirqs_on
/* Now enable for real */
LOAD_REG_IMMEDIATE(r10, MSR_KERNEL | MSR_EE)
mtmsr r10
REST_GPR(0, r1)
REST_4GPRS(3, r1)
REST_2GPRS(7, r1)
b DoSyscall
#endif /* CONFIG_TRACE_IRQFLAGS */
.globl transfer_to_syscall
transfer_to_syscall:
SAVE_NVGPRS(r1)
#ifdef CONFIG_PPC_BOOK3S_32
kuep_lock r11, r12
#endif
#ifdef CONFIG_TRACE_IRQFLAGS
andi. r12,r9,MSR_EE
beq- trace_syscall_entry_irq_off
#endif /* CONFIG_TRACE_IRQFLAGS */
/*
* Handle a system call.
*/
.stabs "arch/powerpc/kernel/",N_SO,0,0,0f
.stabs "entry_32.S",N_SO,0,0,0f
0:
_GLOBAL(DoSyscall)
stw r3,ORIG_GPR3(r1)
li r12,0
stw r12,RESULT(r1)
#ifdef CONFIG_TRACE_IRQFLAGS
/* Make sure interrupts are enabled */
mfmsr r11
andi. r12,r11,MSR_EE
/* We came in with interrupts disabled, we WARN and mark them enabled
* for lockdep now */
0: tweqi r12, 0
EMIT_BUG_ENTRY 0b,__FILE__,__LINE__, BUGFLAG_WARNING
#endif /* CONFIG_TRACE_IRQFLAGS */
lwz r11,TI_FLAGS(r2)
andi. r11,r11,_TIF_SYSCALL_DOTRACE
bne- syscall_dotrace
syscall_dotrace_cont:
cmplwi 0,r0,NR_syscalls
lis r10,sys_call_table@h
ori r10,r10,sys_call_table@l
slwi r0,r0,2
bge- 66f
barrier_nospec_asm
/*
* Prevent the load of the handler below (based on the user-passed
* system call number) being speculatively executed until the test
* against NR_syscalls and branch to .66f above has
* committed.
*/
/* Calling convention has r9 = orig r0, r10 = regs */
addi r10,r1,STACK_FRAME_OVERHEAD
mr r9,r0
stw r10,THREAD+PT_REGS(r2)
bl system_call_exception
lwzx r10,r10,r0 /* Fetch system call handler [ptr] */
mtlr r10
addi r9,r1,STACK_FRAME_OVERHEAD
PPC440EP_ERR42
blrl /* Call handler */
.globl ret_from_syscall
ret_from_syscall:
#ifdef CONFIG_DEBUG_RSEQ
/* Check whether the syscall is issued inside a restartable sequence */
stw r3,GPR3(r1)
addi r3,r1,STACK_FRAME_OVERHEAD
bl rseq_syscall
lwz r3,GPR3(r1)
#endif
mr r6,r3
/* disable interrupts so current_thread_info()->flags can't change */
LOAD_REG_IMMEDIATE(r10,MSR_KERNEL) /* doesn't include MSR_EE */
/* Note: We don't bother telling lockdep about it */
mtmsr r10
lwz r9,TI_FLAGS(r2)
li r8,-MAX_ERRNO
andi. r0,r9,(_TIF_SYSCALL_DOTRACE|_TIF_SINGLESTEP|_TIF_USER_WORK_MASK|_TIF_PERSYSCALL_MASK)
bne- syscall_exit_work
cmplw 0,r3,r8
blt+ syscall_exit_cont
lwz r11,_CCR(r1) /* Load CR */
neg r3,r3
oris r11,r11,0x1000 /* Set SO bit in CR */
stw r11,_CCR(r1)
syscall_exit_cont:
lwz r8,_MSR(r1)
#ifdef CONFIG_TRACE_IRQFLAGS
/* If we are going to return from the syscall with interrupts
* off, we trace that here. It shouldn't normally happen.
*/
andi. r10,r8,MSR_EE
bne+ 1f
stw r3,GPR3(r1)
bl trace_hardirqs_off
lwz r3,GPR3(r1)
1:
#endif /* CONFIG_TRACE_IRQFLAGS */
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. */
......@@ -453,12 +359,6 @@ syscall_exit_cont:
cmplwi cr0,r5,0
bne- 2f
#endif /* CONFIG_PPC_47x */
1:
BEGIN_FTR_SECTION
lwarx r7,0,r1
END_FTR_SECTION_IFSET(CPU_FTR_NEED_PAIRED_STWCX)
stwcx. r0,0,r1 /* to clear the reservation */
ACCOUNT_CPU_USER_EXIT(r2, r5, r7)
#ifdef CONFIG_PPC_BOOK3S_32
kuep_unlock r5, r7
#endif
......@@ -466,21 +366,36 @@ END_FTR_SECTION_IFSET(CPU_FTR_NEED_PAIRED_STWCX)
lwz r4,_LINK(r1)
lwz r5,_CCR(r1)
mtlr r4
mtcr r5
lwz r7,_NIP(r1)
lwz r2,GPR2(r1)
lwz r1,GPR1(r1)
lwz r8,_MSR(r1)
cmpwi r3,0
lwz r3,GPR3(r1)
syscall_exit_finish:
#if defined(CONFIG_PPC_8xx) && defined(CONFIG_PERF_EVENTS)
mtspr SPRN_NRI, r0
#endif
mtspr SPRN_SRR0,r7
mtspr SPRN_SRR1,r8
bne 3f
mtcr r5
1: lwz r2,GPR2(r1)
lwz r1,GPR1(r1)
rfi
#ifdef CONFIG_40x
b . /* Prevent prefetch past rfi */
#endif
_ASM_NOKPROBE_SYMBOL(syscall_exit_finish)
3: mtcr r5
lwz r4,_CTR(r1)
lwz r5,_XER(r1)
REST_NVGPRS(r1)
mtctr r4
mtxer r5
lwz r0,GPR0(r1)
lwz r3,GPR3(r1)
REST_8GPRS(4,r1)
lwz r12,GPR12(r1)
b 1b
#ifdef CONFIG_44x
2: li r7,0
iccci r0,r0
......@@ -488,9 +403,6 @@ _ASM_NOKPROBE_SYMBOL(syscall_exit_finish)
b 1b
#endif /* CONFIG_44x */
66: li r3,-ENOSYS
b ret_from_syscall
.globl ret_from_fork
ret_from_fork:
REST_NVGPRS(r1)
......@@ -509,82 +421,6 @@ ret_from_kernel_thread:
li r3,0
b ret_from_syscall
/* Traced system call support */
syscall_dotrace:
SAVE_NVGPRS(r1)
li r0,0xc00
stw r0,_TRAP(r1)
addi r3,r1,STACK_FRAME_OVERHEAD
bl do_syscall_trace_enter
/*
* Restore argument registers possibly just changed.
* We use the return value of do_syscall_trace_enter
* for call number to look up in the table (r0).
*/
mr r0,r3
lwz r3,GPR3(r1)
lwz r4,GPR4(r1)
lwz r5,GPR5(r1)
lwz r6,GPR6(r1)
lwz r7,GPR7(r1)
lwz r8,GPR8(r1)
REST_NVGPRS(r1)
cmplwi r0,NR_syscalls
/* Return code is already in r3 thanks to do_syscall_trace_enter() */
bge- ret_from_syscall
b syscall_dotrace_cont
syscall_exit_work:
andi. r0,r9,_TIF_RESTOREALL
beq+ 0f
REST_NVGPRS(r1)
b 2f
0: cmplw 0,r3,r8
blt+ 1f
andi. r0,r9,_TIF_NOERROR
bne- 1f
lwz r11,_CCR(r1) /* Load CR */
neg r3,r3
oris r11,r11,0x1000 /* Set SO bit in CR */
stw r11,_CCR(r1)
1: stw r6,RESULT(r1) /* Save result */
stw r3,GPR3(r1) /* Update return value */
2: andi. r0,r9,(_TIF_PERSYSCALL_MASK)
beq 4f
/* Clear per-syscall TIF flags if any are set. */
li r11,_TIF_PERSYSCALL_MASK
addi r12,r2,TI_FLAGS
3: lwarx r8,0,r12
andc r8,r8,r11
stwcx. r8,0,r12
bne- 3b
4: /* Anything which requires enabling interrupts? */
andi. r0,r9,(_TIF_SYSCALL_DOTRACE|_TIF_SINGLESTEP)
beq ret_from_except
/* Re-enable interrupts. There is no need to trace that with
* lockdep as we are supposed to have IRQs on at this point
*/
ori r10,r10,MSR_EE
mtmsr r10
/* Save NVGPRS if they're not saved already */
lwz r4,_TRAP(r1)
andi. r4,r4,1
beq 5f
SAVE_NVGPRS(r1)
li r4,0xc00
stw r4,_TRAP(r1)
5:
addi r3,r1,STACK_FRAME_OVERHEAD
bl do_syscall_trace_leave
b ret_from_except_full
/*
* System call was called from kernel. We get here with SRR1 in r9.
* Mark the exception as recoverable once we have retrieved SRR0,
......
arch/powerpc/kernel/head_32.h
View file @ 6f76a011
......@@ -154,17 +154,12 @@
SAVE_GPR(0, r11)
SAVE_4GPRS(3, r11)
SAVE_2GPRS(7, r11)
addi r11,r1,STACK_FRAME_OVERHEAD
addi r2,r12,-THREAD
stw r11,PT_REGS(r12)
#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
#endif
ACCOUNT_CPU_USER_ENTRY(r2, r11, r12)
#if defined(CONFIG_40x)
beq+ 3f
/* From user and task is ptraced - load up global dbcr0 */
li r12,-1 /* clear all pending debug events */
......@@ -176,21 +171,8 @@
lwz r12,4(r11)
addi r12,r12,-1
stw r12,4(r11)
#endif
3:
#ifdef CONFIG_TRACE_IRQFLAGS
/*
* If MSR is changing we need to keep interrupts disabled at this point
* otherwise we might risk taking an interrupt before we tell lockdep
* they are enabled.
*/
LOAD_REG_IMMEDIATE(r10, MSR_KERNEL)
rlwimi r10, r9, 0, MSR_EE
#else
LOAD_REG_IMMEDIATE(r10, MSR_KERNEL | MSR_EE)
#endif
mtmsr r10
b transfer_to_syscall /* jump to handler */
99: b ret_from_kernel_syscall
.endm
......
arch/powerpc/kernel/head_booke.h
View file @ 6f76a011
......@@ -131,14 +131,11 @@ ALT_FTR_SECTION_END_IFSET(CPU_FTR_EMB_HV)
SAVE_4GPRS(3, r11)
SAVE_2GPRS(7, r11)
addi r11,r1,STACK_FRAME_OVERHEAD
addi r2,r10,-THREAD
stw r11,PT_REGS(r10)
/* 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
ACCOUNT_CPU_USER_ENTRY(r2, r11, r12)
beq+ 3f
/* From user and task is ptraced - load up global dbcr0 */
li r12,-1 /* clear all pending debug events */
......@@ -157,20 +154,6 @@ ALT_FTR_SECTION_END_IFSET(CPU_FTR_EMB_HV)
stw r12,4(r11)
3:
#ifdef CONFIG_TRACE_IRQFLAGS
/*
* If MSR is changing we need to keep interrupts disabled at this point
* otherwise we might risk taking an interrupt before we tell lockdep
* they are enabled.
*/
lis r10, MSR_KERNEL@h
ori r10, r10, MSR_KERNEL@l
rlwimi r10, r9, 0, MSR_EE
#else
lis r10, (MSR_KERNEL | MSR_EE)@h
ori r10, r10, (MSR_KERNEL | MSR_EE)@l
#endif
mtmsr r10
b transfer_to_syscall /* jump to handler */
99: b ret_from_kernel_syscall
.endm
......
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