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Commit e494239a authored by Vineet Gupta's avatar Vineet Gupta
Browse files

ARCv2: support manual regfile save on interrupts 



There's a hardware bug which affects the HSDK platform, triggered by
micro-ops for auto-saving regfile on taken interrupt. The workaround is
to inhibit autosave.

Signed-off-by: default avatarVineet Gupta <vgupta@synopsys.com>
parent d5e3c55e

arch/arc/Kconfig

+8 −0
Original line number Diff line number Diff line
@@ -407,6 +407,14 @@ config ARC_HAS_ACCL_REGS 
	  (also referred to as r58:r59). These can also be used by gcc as GPR so

	  kernel needs to save/restore per process



config ARC_IRQ_NO_AUTOSAVE

	bool "Disable hardware autosave regfile on interrupts"

	default n

	help

	  On HS cores, taken interrupt auto saves the regfile on stack.

	  This is programmable and can be optionally disabled in which case

	  software INTERRUPT_PROLOGUE/EPILGUE do the needed work



endif	# ISA_ARCV2



endmenu   # "ARC CPU Configuration"

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

+54 −0
Original line number Diff line number Diff line
@@ -17,6 +17,33 @@ 
	;

	; Now manually save: r12, sp, fp, gp, r25



#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



#ifdef CONFIG_ARC_HAS_ACCL_REGS

	PUSH	r59

	PUSH	r58
@@ -86,6 +113,33 @@ 
	POP	r59

#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

#endif



.endm



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

arch/arc/kernel/entry-arcv2.S

+3 −1
Original line number Diff line number Diff line
@@ -209,7 +209,9 @@ restore_regs: 
;####### Return from Intr #######



debug_marker_l1:

	bbit1.nt r0, STATUS_DE_BIT, .Lintr_ret_to_delay_slot

	; bbit1.nt r0, STATUS_DE_BIT, .Lintr_ret_to_delay_slot

	btst	r0, STATUS_DE_BIT		; Z flag set if bit clear

	bnz	.Lintr_ret_to_delay_slot	; branch if STATUS_DE_BIT set



.Lisr_ret_fast_path:

	; Handle special case #1: (Entry via Exception, Return via IRQ)

arch/arc/kernel/intc-arcv2.c

+2 −0
Original line number Diff line number Diff line
@@ -49,11 +49,13 @@ void arc_init_IRQ(void) 


	*(unsigned int *)&ictrl = 0;



#ifndef CONFIG_ARC_IRQ_NO_AUTOSAVE

	ictrl.save_nr_gpr_pairs = 6;	/* r0 to r11 (r12 saved manually) */

	ictrl.save_blink = 1;

	ictrl.save_lp_regs = 1;		/* LP_COUNT, LP_START, LP_END */

	ictrl.save_u_to_u = 0;		/* user ctxt saved on kernel stack */

	ictrl.save_idx_regs = 1;	/* JLI, LDI, EI */

#endif



	WRITE_AUX(AUX_IRQ_CTRL, ictrl);

arch/arc/plat-hsdk/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -9,6 +9,7 @@ menuconfig ARC_SOC_HSDK 
	bool "ARC HS Development Kit SOC"

	depends on ISA_ARCV2

	select ARC_HAS_ACCL_REGS

	select ARC_IRQ_NO_AUTOSAVE

	select CLK_HSDK

	select RESET_HSDK

	select HAVE_PCI