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powerpc/64: Rearrange 64-bit _switch to prepare for 32/64 merge

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More some 64-bit specifics out from the function epilogue and rearrange
this to be a bit neater, use 32-bit mem ops for CR save/restore, and
change some register numbers.

This is preparation to consolidate 32-bit and 64-bit switch code.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230606132447.315714-3-npiggin@gmail.com
This commit is contained in:
Nicholas Piggin 2023-06-06 23:24:43 +10:00 committed by Michael Ellerman
parent d6b87c3eb6
commit 0eb8088b5a
1 changed files with 18 additions and 20 deletions
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38
arch/powerpc/kernel/entry_64.S
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@ -190,12 +190,13 @@ _GLOBAL(_switch)
mflr r0
std r0,16(r1)
stdu r1,-SWITCH_FRAME_SIZE(r1)
std r1,KSP(r3) /* Set old stack pointer */
/* r3-r13 are caller saved -- Cort */
SAVE_NVGPRS(r1)
std r0,_NIP(r1) /* Return to switch caller */
mfcr r23
std r23,_CCR(r1)
std r1,KSP(r3) /* Set old stack pointer */
mfcr r0
stw r0,_CCR(r1)
ld r8,KSP(r4) /* Load new stack pointer */
kuap_check_amr r9, r10
@ -232,14 +233,20 @@ _GLOBAL(_switch)
DCBT_BOOK3S_STOP_ALL_STREAM_IDS(r6)
#endif
addi r6,r4,-THREAD /* Convert THREAD to 'current' */
std r6,PACACURRENT(r13) /* Set new 'current' */
addi r3,r3,-THREAD /* old thread -> task_struct for return value */
addi r6,r4,-THREAD /* new thread -> task_struct */
std r6,PACACURRENT(r13) /* Set new task_struct to 'current' */
#if defined(CONFIG_STACKPROTECTOR)
ld r6, TASK_CANARY(r6)
std r6, PACA_CANARY(r13)
#endif
ld r8,KSP(r4) /* new stack pointer */
/* Set the new PACAKSAVE */
clrrdi r7, r8, THREAD_SHIFT /* base of new stack */
/* Note: this uses SWITCH_FRAME_SIZE rather than INT_FRAME_SIZE
because we don't need to leave the 288-byte ABI gap at the
top of the kernel stack. */
addi r7,r7,THREAD_SIZE-SWITCH_FRAME_SIZE
std r7,PACAKSAVE(r13)
#ifdef CONFIG_PPC_64S_HASH_MMU
BEGIN_MMU_FTR_SECTION
@ -247,12 +254,6 @@ BEGIN_MMU_FTR_SECTION
END_MMU_FTR_SECTION_IFCLR(MMU_FTR_TYPE_RADIX)
#endif
clrrdi r7, r8, THREAD_SHIFT /* base of new stack */
/* Note: this uses SWITCH_FRAME_SIZE rather than INT_FRAME_SIZE
because we don't need to leave the 288-byte ABI gap at the
top of the kernel stack. */
addi r7,r7,THREAD_SIZE-SWITCH_FRAME_SIZE
/*
* PMU interrupts in radix may come in here. They will use r1, not
* PACAKSAVE, so this stack switch will not cause a problem. They
@ -262,18 +263,15 @@ END_MMU_FTR_SECTION_IFCLR(MMU_FTR_TYPE_RADIX)
* active on the new CPU, will order those stores.
*/
mr r1,r8 /* start using new stack pointer */
std r7,PACAKSAVE(r13)
ld r6,_CCR(r1)
mtcrf 0xFF,r6
lwz r0,_CCR(r1)
mtcrf 0xFF,r0
/* r3-r13 are destroyed -- Cort */
REST_NVGPRS(r1)
/* convert old thread to its task_struct for return value */
addi r3,r3,-THREAD
ld r7,_NIP(r1) /* Return to _switch caller in new task */
mtlr r7
ld r0,_NIP(r1) /* Return to _switch caller in new task */
mtlr r0
addi r1,r1,SWITCH_FRAME_SIZE
blr