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ARCv2: support manual regfile save on interrupts

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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: Vineet Gupta <vgupta@synopsys.com>
This commit is contained in:
Vineet Gupta 2018-06-06 10:20:37 -07:00
parent d5e3c55e01
commit e494239a00
5 changed files with 68 additions and 1 deletions
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8
arch/arc/Kconfig
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@ -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"

54
arch/arc/include/asm/entry-arcv2.h
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@ -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
/*------------------------------------------------------------------------*/

4
arch/arc/kernel/entry-arcv2.S
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@ -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)

2
arch/arc/kernel/intc-arcv2.c
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@ -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);

1
arch/arc/plat-hsdk/Kconfig
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@ -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