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powerpc/32: implement fast entry for syscalls on BOOKE 

This patch implements a fast entry for syscalls.

Syscalls don't have to preserve non volatile registers except LR.

This patch then implement a fast entry for syscalls, where
volatile registers get clobbered.

As this entry is dedicated to syscall it always sets MSR_EE
and warns in case MSR_EE was previously off

It also assumes that the call is always from user, system calls are
unexpected from kernel.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Christophe Leroy 2019-04-30 12:39:03 +00:00 committed by Michael Ellerman
parent b86fb88855
commit 1a4b739bbb
4 changed files with 100 additions and 16 deletions
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7
arch/powerpc/kernel/entry_32.S
View File

@ -342,7 +342,6 @@ stack_ovf:
SYNC
RFI
#ifndef CONFIG_BOOKE /* to be removed once BOOKE uses fast syscall entry */
#ifdef CONFIG_TRACE_IRQFLAGS
trace_syscall_entry_irq_off:
/*
@ -369,7 +368,6 @@ transfer_to_syscall:
andi. r12,r9,MSR_EE
beq- trace_syscall_entry_irq_off
#endif /* CONFIG_TRACE_IRQFLAGS */
#endif /* !CONFIG_BOOKE */
/*
* Handle a system call.
@ -382,11 +380,6 @@ _GLOBAL(DoSyscall)
stw r3,ORIG_GPR3(r1)
li r12,0
stw r12,RESULT(r1)
#ifdef CONFIG_BOOKE /* to be removed once BOOKE uses fast syscall entry */
lwz r11,_CCR(r1) /* Clear SO bit in CR */
rlwinm r11,r11,0,4,2
stw r11,_CCR(r1)
#endif
#ifdef CONFIG_TRACE_IRQFLAGS
/* Make sure interrupts are enabled */
mfmsr r11

3
arch/powerpc/kernel/head_44x.S
View File

@ -285,8 +285,7 @@ interrupt_base:
#endif
/* System Call Interrupt */
START_EXCEPTION(SystemCall)
NORMAL_EXCEPTION_PROLOG(BOOKE_INTERRUPT_SYSCALL)
EXC_XFER_SYS(0x0c00, DoSyscall)
SYSCALL_ENTRY 0xc00 BOOKE_INTERRUPT_SYSCALL
/* Auxiliary Processor Unavailable Interrupt */
EXCEPTION(0x2020, BOOKE_INTERRUPT_AP_UNAVAIL, \

103
arch/powerpc/kernel/head_booke.h
View File

@ -6,6 +6,8 @@
#include <asm/kvm_asm.h>
#include <asm/kvm_booke_hv_asm.h>
#ifdef __ASSEMBLY__
/*
* Macros used for common Book-e exception handling
*/
@ -81,6 +83,101 @@ END_BTB_FLUSH_SECTION
SAVE_4GPRS(3, r11); \
SAVE_2GPRS(7, r11)
.macro SYSCALL_ENTRY trapno intno
mfspr r10, SPRN_SPRG_THREAD
#ifdef CONFIG_KVM_BOOKE_HV
BEGIN_FTR_SECTION
mtspr SPRN_SPRG_WSCRATCH0, r10
stw r11, THREAD_NORMSAVE(0)(r10)
stw r13, THREAD_NORMSAVE(2)(r10)
mfcr r13 /* save CR in r13 for now */
mfspr r11, SPRN_SRR1
mtocrf 0x80, r11 /* check MSR[GS] without clobbering reg */
bf 3, 1975f
b kvmppc_handler_BOOKE_INTERRUPT_\intno\()_SPRN_SRR1
1975:
mr r12, r13
lwz r13, THREAD_NORMSAVE(2)(r10)
FTR_SECTION_ELSE
#endif
mfcr r12
#ifdef CONFIG_KVM_BOOKE_HV
ALT_FTR_SECTION_END_IFSET(CPU_FTR_EMB_HV)
#endif
BOOKE_CLEAR_BTB(r11)
lwz r11, TASK_STACK - THREAD(r10)
rlwinm r12,r12,0,4,2 /* Clear SO bit in CR */
ALLOC_STACK_FRAME(r11, THREAD_SIZE - INT_FRAME_SIZE)
stw r12, _CCR(r11) /* save various registers */
mflr r12
stw r12,_LINK(r11)
mfspr r12,SPRN_SRR0
stw r1, GPR1(r11)
mfspr r9,SPRN_SRR1
stw r1, 0(r11)
mr r1, r11
stw r12,_NIP(r11)
rlwinm r9,r9,0,14,12 /* clear MSR_WE (necessary?) */
lis r12, STACK_FRAME_REGS_MARKER@ha /* exception frame marker */
stw r2,GPR2(r11)
addi r12, r12, STACK_FRAME_REGS_MARKER@l
stw r9,_MSR(r11)
li r2, \trapno + 1
stw r12, 8(r11)
stw r2,_TRAP(r11)
SAVE_GPR(0, r11)
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 */
mtspr SPRN_DBSR,r12
lis r11,global_dbcr0@ha
tophys(r11,r11)
addi r11,r11,global_dbcr0@l
#ifdef CONFIG_SMP
lwz r9,TASK_CPU(r2)
slwi r9,r9,3
add r11,r11,r9
#endif
lwz r12,0(r11)
mtspr SPRN_DBCR0,r12
lwz r12,4(r11)
addi r12,r12,-1
stw r12,4(r11)
3:
tovirt(r2, r2) /* set r2 to current */
lis r11, transfer_to_syscall@h
ori r11, r11, transfer_to_syscall@l
#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
mtspr SPRN_SRR1,r10
mtspr SPRN_SRR0,r11
SYNC
RFI /* jump to handler, enable MMU */
.endm
/* To handle the additional exception priority levels on 40x and Book-E
* processors we allocate a stack per additional priority level.
*
@ -245,10 +342,6 @@ label:
EXC_XFER_TEMPLATE(hdlr, n+1, MSR_KERNEL, transfer_to_handler, \
ret_from_except)
#define EXC_XFER_SYS(n, hdlr) \
EXC_XFER_TEMPLATE(hdlr, n+1, MSR_KERNEL | MSR_EE, transfer_to_handler, \
ret_from_except)
/* Check for a single step debug exception while in an exception
* handler before state has been saved. This is to catch the case
* where an instruction that we are trying to single step causes
@ -418,7 +511,7 @@ label:
1: addi r3,r1,STACK_FRAME_OVERHEAD; \
EXC_XFER_STD(0x800, kernel_fp_unavailable_exception)
#ifndef __ASSEMBLY__
#else /* __ASSEMBLY__ */
struct exception_regs {
unsigned long mas0;
unsigned long mas1;

3
arch/powerpc/kernel/head_fsl_booke.S
View File

@ -413,8 +413,7 @@ interrupt_base:
/* System Call Interrupt */
START_EXCEPTION(SystemCall)
NORMAL_EXCEPTION_PROLOG(SYSCALL)
EXC_XFER_SYS(0x0c00, DoSyscall)
SYSCALL_ENTRY 0xc00 SYSCALL
/* Auxiliary Processor Unavailable Interrupt */
EXCEPTION(0x2900, AP_UNAVAIL, AuxillaryProcessorUnavailable, \