Commit 0eb8088b authored by Nicholas Piggin's avatar Nicholas Piggin Committed by Michael Ellerman
Browse files

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



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: default avatarNicholas Piggin <npiggin@gmail.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230606132447.315714-3-npiggin@gmail.com
parent d6b87c3e

arch/powerpc/kernel/entry_64.S

+18 −20
Original line number Diff line number Diff line
@@ -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