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Save a few more cycles in cpu_switch() and cpu_throw().

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This commit is contained in:
Olivier Houchard 2004-12-12 19:21:58 +00:00
parent 6c98f40194
commit eb64032876
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=138751
1 changed files with 26 additions and 31 deletions
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57
sys/arm/arm/swtch.S
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@ -128,11 +128,9 @@ __FBSDID("$FreeBSD$");
.Lcpu_do_powersave:
.word _C_LABEL(cpu_do_powersave)
ENTRY(cpu_throw)
mov r4, r0
mov r5, r1
/*
* r4 = oldtd
* r5 = newtd
*/
@ -148,7 +146,6 @@ ENTRY(cpu_throw)
/*
* r0 = Pointer to L1 slot for vector_page (or NULL)
* r1 = lwp0's DACR
* r4 = lwp we're switching from
* r5 = lwp0
* r6 = exit func
* r7 = lwp0's PCB
@ -200,9 +197,15 @@ ENTRY(cpu_throw)
ldr r13, [r7, #(PCB_SP)]
#endif
mov r0, #0x00000000 /* r5 = old lwp = NULL */
mov r1, r5
b .Lswitch_resume
/* We have a new curthread now so make a note it */
ldr r6, .Lcurthread
str r5, [r6]
/* Hook in a new pcb */
ldr r6, .Lcurpcb
str r7, [r6]
ldmfd sp, {r4-r7, pc}
ENTRY(cpu_switch)
stmfd sp!, {r4-r7, lr}
@ -228,16 +231,6 @@ ENTRY(cpu_switch)
ldr r2, [r1, #TD_PCB]
str r2, [r7]
/*
* If the old lwp on entry to cpu_switch was zero then the
* process that called it was exiting. This means that we do
* not need to save the current context. Instead we can jump
* straight to restoring the context for the new process.
*/
teq r0, #0x00000000
beq .Lswitch_return
/* rem: r1 = new process */
/* rem: interrupts are enabled */
@ -267,16 +260,15 @@ ENTRY(cpu_switch)
/* r1 now free! */
/*
* This can be optimised... We know we want to go from SVC32
* mode to UND32 mode
*/
mrs r3, cpsr
bic r2, r3, #(PSR_MODE)
orr r2, r2, #(PSR_UND32_MODE)
msr cpsr_c, r2
/*
* We can do that, since
* PSR_SVC32_MODE|PSR_UND32_MODE == MSR_UND32_MODE
*/
orr r8, r3, #(PSR_UND32_MODE)
msr cpsr_c, r8
str sp, [r8, #(PCB_UND_SP)]
str sp, [r2, #(PCB_UND_SP)]
msr cpsr_c, r3 /* Restore the old mode */
/* rem: r8 = old PCB */
@ -378,6 +370,10 @@ ENTRY(cpu_switch)
movne r0, #0 /* We *know* vector_page's VA is 0x0 */
movne lr, pc
ldrne pc, [r10, #CF_TLB_FLUSHID_SE]
/*
* We can do that, since
* PSR_SVC32_MODE|PSR_UND32_MODE == MSR_UND32_MODE
*/
.Lcs_context_switched:
@ -385,14 +381,13 @@ ENTRY(cpu_switch)
/* rem: r9 = new PCB */
/*
* This can be optimised... We know we want to go from SVC32
* mode to UND32 mode
*/
mrs r3, cpsr
bic r2, r3, #(PSR_MODE)
orr r2, r2, #(PSR_UND32_MODE)
msr cpsr_c, r2
/*
* We can do that, since
* PSR_SVC32_MODE|PSR_UND32_MODE == MSR_UND32_MODE
*/
orr r2, r3, #(PSR_UND32_MODE)
msr cpsr_c, r2
ldr sp, [r9, #(PCB_UND_SP)]