Commit a4880801 authored by Vineet Gupta's avatar Vineet Gupta
Browse files

ARCv2: entry: rewrite to enable use of double load/stores LDD/STD 



 - the motivation was to be remove blatent copy-paste due to hasty support
   of CONFIG_ARC_IRQ_NO_AUTOSAVE support

 - but with refactoring we could use LDD/STD to greatly optimize the code

Signed-off-by: default avatarVineet Gupta <vgupta@synopsys.com>
parent ab854bfc

arch/arc/include/asm/entry-arcv2.h

+140 −157
Original line number Diff line number Diff line
@@ -46,7 +46,8 @@ 
 */



/*------------------------------------------------------------------------*/

.macro INTERRUPT_PROLOGUE	called_from

.macro INTERRUPT_PROLOGUE



	; (A) Before jumping to Interrupt Vector, hardware micro-ops did following:

	;   1. SP auto-switched to kernel mode stack

	;   2. STATUS32.Z flag set if in U mode at time of interrupt (U:1,K:0)
@@ -57,39 +58,87 @@ 
	; (B) Manually saved some regs: r12,r25,r30, sp,fp,gp, ACCL pair



#ifdef CONFIG_ARC_IRQ_NO_AUTOSAVE

.ifnc \called_from, exception

	st.as	r9, [sp, -10]	; save r9 in it's final stack slot

	sub	sp, sp, 12	; skip JLI, LDI, EI



	PUSH	lp_count

	PUSHAX	lp_start

	PUSHAX	lp_end

	PUSH	blink



	PUSH	r11

	PUSH	r10



	sub	sp, sp, 4	; skip r9



	PUSH	r8

	PUSH	r7

	PUSH	r6

	PUSH	r5

	PUSH	r4

	PUSH	r3

	PUSH	r2

	PUSH	r1

	PUSH	r0

.endif

#endif

	; carve pt_regs on stack (case #3), PC/STAT32 already on stack

	sub	sp, sp, SZ_PT_REGS - 8



#ifdef CONFIG_ARC_HAS_ACCL_REGS

	PUSH	r59

	PUSH	r58

	__SAVE_REGFILE_HARD

#else

	; carve pt_regs on stack (case #4), which grew partially already

	sub	sp, sp, PT_r0

#endif



	PUSH	r30

	PUSH	r12

	__SAVE_REGFILE_SOFT

.endm



/*------------------------------------------------------------------------*/

.macro EXCEPTION_PROLOGUE



	; (A) Before jumping to Exception Vector, hardware micro-ops did following:

	;   1. SP auto-switched to kernel mode stack

	;   2. STATUS32.Z flag set if in U mode at time of exception (U:1,K:0)

	;

	; (B) Manually save the complete reg file below



	sub	sp, sp, SZ_PT_REGS	; carve pt_regs



	; _HARD saves r10 clobbered by _SOFT as scratch hence comes first



	__SAVE_REGFILE_HARD

	__SAVE_REGFILE_SOFT



	st	r0, [sp]	; orig_r0



	lr	r10, [eret]

	lr	r11, [erstatus]

	ST2	r10, r11, PT_ret



	lr	r10, [ecr]

	lr	r11, [erbta]

	ST2	r10, r11, PT_event

	mov	r9, r10



	; OUTPUT: r9 has ECR

.endm



/*------------------------------------------------------------------------

 * This macro saves the registers manually which would normally be autosaved

 * by hardware on taken interrupts. It is used by

 *   - exception handlers (which don't have autosave)

 *   - interrupt autosave disabled due to CONFIG_ARC_IRQ_NO_AUTOSAVE

 */

.macro __SAVE_REGFILE_HARD



	ST2	r0,  r1,  PT_r0

	ST2	r2,  r3,  PT_r2

	ST2	r4,  r5,  PT_r4

	ST2	r6,  r7,  PT_r6

	ST2	r8,  r9,  PT_r8

	ST2	r10, r11, PT_r10



	st	blink, [sp, PT_blink]



	lr	r10, [lp_end]

	lr	r11, [lp_start]

	ST2	r10, r11, PT_lpe



	st	lp_count, [sp, PT_lpc]



	; skip JLI, LDI, EI for now

.endm



/*------------------------------------------------------------------------

 * This macros saves a bunch of other registers which can't be autosaved for

 * various reasons:

 *   - r12: the last caller saved scratch reg since hardware saves in pairs so r0-r11

 *   - r30: free reg, used by gcc as scratch

 *   - ACCL/ACCH pair when they exist

 */

.macro __SAVE_REGFILE_SOFT



	ST2	gp, fp, PT_r26		; gp (r26), fp (r27)



	st	r12, [sp, PT_sp + 4]

	st	r30, [sp, PT_sp + 8]



	; Saving pt_regs->sp correctly requires some extra work due to the way

	; Auto stack switch works
@@ -100,46 +149,32 @@ 
	; 2. Upon entry SP is always saved (for any inspection, unwinding etc),

	;    but on return, restored only if U mode



	lr	r9, [AUX_USER_SP]			; U mode SP

	lr	r10, [AUX_USER_SP]	; U mode SP



	mov.nz	r9, sp

	add.nz	r9, r9, SZ_PT_REGS - PT_sp - 4		; K mode SP

	; ISA requires ADD.nz to have same dest and src reg operands

	mov.nz	r10, sp

	add.nz	r10, r10, SZ_PT_REGS	; K mode SP



	PUSH	r9					; SP (pt_regs->sp)



	PUSH	fp

	PUSH	gp

	st	r10, [sp, PT_sp]	; SP (pt_regs->sp)



#ifdef CONFIG_ARC_CURR_IN_REG

	PUSH	r25			; user_r25

	st	r25, [sp, PT_user_r25]

	GET_CURR_TASK_ON_CPU	r25

#else

	sub	sp, sp, 4

#endif



.ifnc \called_from, exception

	sub	sp, sp, 12	; BTA/ECR/orig_r0 placeholder per pt_regs

.endif

#ifdef CONFIG_ARC_HAS_ACCL_REGS

	ST2	r58, r59, PT_sp + 12

#endif



.endm



/*------------------------------------------------------------------------*/

.macro INTERRUPT_EPILOGUE	called_from

.macro __RESTORE_REGFILE_SOFT



	; INPUT: r0 has STAT32 of calling context

	; INPUT: Z flag set if returning to K mode

.ifnc \called_from, exception

	add	sp, sp, 12	; skip BTA/ECR/orig_r0 placeholderss

.endif



#ifdef CONFIG_ARC_CURR_IN_REG

	POP	r25

#else

	add	sp, sp, 4

#endif

	LD2	gp, fp, PT_r26		; gp (r26), fp (r27)



	POP	gp

	POP	fp

	ld	r12, [sp, PT_sp + 4]

	ld	r30, [sp, PT_sp + 8]



	; Restore SP (into AUX_USER_SP) only if returning to U mode

	;  - for K mode, it will be implicitly restored as stack is unwound
@@ -147,129 +182,77 @@ 
	;    but that doesn't really matter

	bz	1f



	POPAX	AUX_USER_SP

	ld	r10, [sp, PT_sp]	; SP (pt_regs->sp)

	sr	r10, [AUX_USER_SP]

1:

	POP	r12

	POP	r30



#ifdef CONFIG_ARC_HAS_ACCL_REGS

	POP	r58

	POP	r59

#ifdef CONFIG_ARC_CURR_IN_REG

	ld	r25, [sp, PT_user_r25]

#endif



#ifdef CONFIG_ARC_IRQ_NO_AUTOSAVE

.ifnc \called_from, exception

	POP	r0

	POP	r1

	POP	r2

	POP	r3

	POP	r4

	POP	r5

	POP	r6

	POP	r7

	POP	r8

	POP	r9

	POP	r10

	POP	r11



	POP	blink

	POPAX	lp_end

	POPAX	lp_start



	POP	r9

	mov	lp_count, r9



	add	sp, sp, 12	; skip JLI, LDI, EI

	ld.as	r9, [sp, -10]	; reload r9 which got clobbered

.endif

#ifdef CONFIG_ARC_HAS_ACCL_REGS

	LD2	r58, r59, PT_sp + 12

#endif



.endm



/*------------------------------------------------------------------------*/

.macro EXCEPTION_PROLOGUE

.macro __RESTORE_REGFILE_HARD



	; (A) Before jumping to Exception Vector, hardware micro-ops did following:

	;   1. SP auto-switched to kernel mode stack

	;   2. STATUS32.Z flag set if in U mode at time of exception (U:1,K:0)

	;

	; (B) Manually save the complete reg file below

	ld	blink, [sp, PT_blink]



	PUSH	r9		; freeup a register: slot of erstatus

	LD2	r10, r11, PT_lpe

	sr	r10, [lp_end]

	sr	r11, [lp_start]



	PUSHAX	eret

	sub	sp, sp, 12	; skip JLI, LDI, EI

	PUSH	lp_count

	PUSHAX	lp_start

	PUSHAX	lp_end

	PUSH	blink

	ld	r10, [sp, PT_lpc]	; lp_count can't be target of LD

	mov	lp_count, r10



	PUSH	r11

	PUSH	r10

	LD2	r0,  r1,  PT_r0

	LD2	r2,  r3,  PT_r2

	LD2	r4,  r5,  PT_r4

	LD2	r6,  r7,  PT_r6

	LD2	r8,  r9,  PT_r8

	LD2	r10, r11, PT_r10

.endm



	ld.as	r9,  [sp, 10]	; load stashed r9 (status32 stack slot)

	lr	r10, [erstatus]

	st.as	r10, [sp, 10]	; save status32 at it's right stack slot



	PUSH	r9

	PUSH	r8

	PUSH	r7

	PUSH	r6

	PUSH	r5

	PUSH	r4

	PUSH	r3

	PUSH	r2

	PUSH	r1

	PUSH	r0

/*------------------------------------------------------------------------*/

.macro INTERRUPT_EPILOGUE



	; -- for interrupts, regs above are auto-saved by h/w in that order --

	; Now do what ISR prologue does (manually save r12, sp, fp, gp, r25)

	; INPUT: r0 has STAT32 of calling context

	; INPUT: Z flag set if returning to K mode



	INTERRUPT_PROLOGUE  exception

	; _SOFT clobbers r10 restored by _HARD hence the order



	PUSHAX	erbta

	PUSHAX	ecr		; r9 contains ECR, expected by EV_Trap

	__RESTORE_REGFILE_SOFT



#ifdef CONFIG_ARC_IRQ_NO_AUTOSAVE

	__RESTORE_REGFILE_HARD

	add	sp, sp, SZ_PT_REGS - 8

#else

	add	sp, sp, PT_r0

#endif



	PUSH	r0		; orig_r0

	; OUTPUT: r9 has ECR

.endm



/*------------------------------------------------------------------------*/

.macro EXCEPTION_EPILOGUE



	; INPUT: r0 has STAT32 of calling context

	btst   r0, STATUS_U_BIT	; Z flag set if K, used in INTERRUPT_EPILOGUE



	add	sp, sp, 8	; orig_r0/ECR don't need restoring

	POPAX	erbta



	INTERRUPT_EPILOGUE  exception



	POP	r0

	POP	r1

	POP	r2

	POP	r3

	POP	r4

	POP	r5

	POP	r6

	POP	r7

	POP	r8

	POP	r9

	POP	r10

	POP	r11



	POP	blink

	POPAX	lp_end

	POPAX	lp_start



	POP	r9

	mov	lp_count, r9



	add	sp, sp, 12	; skip JLI, LDI, EI

	POPAX	eret

	POPAX	erstatus



	ld.as	r9, [sp, -12]	; reload r9 which got clobbered



	btst	r0, STATUS_U_BIT	; Z flag set if K, used in restoring SP



	ld	r10, [sp, PT_event + 4]

	sr	r10, [erbta]



	LD2	r10, r11, PT_ret

	sr	r10, [eret]

	sr	r11, [erstatus]



	__RESTORE_REGFILE_SOFT

	__RESTORE_REGFILE_HARD



	add	sp, sp, SZ_PT_REGS

.endm



.macro FAKE_RET_FROM_EXCPN

arch/arc/include/asm/linkage.h

+18 −0
Original line number Diff line number Diff line
@@ -10,6 +10,24 @@ 


#ifdef __ASSEMBLY__



.macro ST2 e, o, off

#ifdef CONFIG_ARC_HAS_LL64

	std	\e, [sp, \off]

#else

	st	\e, [sp, \off]

	st	\o, [sp, \off+4]

#endif

.endm



.macro LD2 e, o, off

#ifdef CONFIG_ARC_HAS_LL64

	ldd	\e, [sp, \off]

#else

	ld	\e, [sp, \off]

	ld	\o, [sp, \off+4]

#endif

.endm



#define ASM_NL		 `	/* use '`' to mark new line in macro */



/* annotation for data we want in DCCM - if enabled in .config */

arch/arc/kernel/asm-offsets.c

+7 −0
Original line number Diff line number Diff line
@@ -55,7 +55,14 @@ int main(void) 
	DEFINE(PT_r5, offsetof(struct pt_regs, r5));

	DEFINE(PT_r6, offsetof(struct pt_regs, r6));

	DEFINE(PT_r7, offsetof(struct pt_regs, r7));

	DEFINE(PT_r8, offsetof(struct pt_regs, r8));

	DEFINE(PT_r10, offsetof(struct pt_regs, r10));

	DEFINE(PT_r26, offsetof(struct pt_regs, r26));

	DEFINE(PT_ret, offsetof(struct pt_regs, ret));

	DEFINE(PT_blink, offsetof(struct pt_regs, blink));

	DEFINE(PT_lpe, offsetof(struct pt_regs, lp_end));

	DEFINE(PT_lpc, offsetof(struct pt_regs, lp_count));

	DEFINE(PT_user_r25, offsetof(struct pt_regs, user_r25));



	DEFINE(SZ_CALLEE_REGS, sizeof(struct callee_regs));

	DEFINE(SZ_PT_REGS, sizeof(struct pt_regs));

arch/arc/kernel/entry-arcv2.S

+2 −2
Original line number Diff line number Diff line
@@ -67,7 +67,7 @@ reserved: 


ENTRY(handle_interrupt)



	INTERRUPT_PROLOGUE  irq

	INTERRUPT_PROLOGUE



	# irq control APIs local_irq_save/restore/disable/enable fiddle with

	# global interrupt enable bits in STATUS32 (.IE for 1 prio, .E[] for 2 prio)
@@ -223,7 +223,7 @@ debug_marker_l1: 
	bset.nz	r11, r11, AUX_IRQ_ACT_BIT_U	; NZ means U

	sr	r11, [AUX_IRQ_ACT]



	INTERRUPT_EPILOGUE  irq

	INTERRUPT_EPILOGUE

	rtie



;####### Return from Exception / pure kernel mode #######

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