ARCv2: support manual regfile save on interrupts

[ Upstream commit e494239a007e601448110ac304fe055951f9de3b ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig
index 9d06c9478a0dd5345d39cbc931d1aae9045db0a5..82050893d0b33ef5c541043629dea99422c6ac59 100644 (file)
--- a/arch/arc/Kconfig
+++ b/arch/arc/Kconfig
@@ -417,6 +417,14 @@ 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"

diff --git a/arch/arc/include/asm/entry-arcv2.h b/arch/arc/include/asm/entry-arcv2.h
index 257a68f3c2feef3a369093f5bade883e814b7648..9f581553dcc36f5a82dc0bc9ae571b8555a79f55 100644 (file)
--- a/arch/arc/include/asm/entry-arcv2.h
+++ b/arch/arc/include/asm/entry-arcv2.h
@@ -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
 
 /*------------------------------------------------------------------------*/

diff --git a/arch/arc/kernel/entry-arcv2.S b/arch/arc/kernel/entry-arcv2.S
index cc558a25b8fa690d1c72afed97f80161e4167db6..562089d62d9d68cf6fd0be3e9c1e607dfb1decc5 100644 (file)
--- a/arch/arc/kernel/entry-arcv2.S
+++ b/arch/arc/kernel/entry-arcv2.S
@@ -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)

diff --git a/arch/arc/kernel/intc-arcv2.c b/arch/arc/kernel/intc-arcv2.c
index 067ea362fb3efc3bc3a9217aaf197763eafb275e..cf18b3e5a934d34c684edcc7aa84533a10f932bf 100644 (file)
--- a/arch/arc/kernel/intc-arcv2.c
+++ b/arch/arc/kernel/intc-arcv2.c
@@ -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);
 

diff --git a/arch/arc/plat-hsdk/Kconfig b/arch/arc/plat-hsdk/Kconfig
index fcc9a9e27e9cb6696c333d93a9cda99a0ebfc5a8..8fb1600b29b762b23a5d9a4d1d8e0865b96bfa01 100644 (file)
--- a/arch/arc/plat-hsdk/Kconfig
+++ b/arch/arc/plat-hsdk/Kconfig
@@ -9,5 +9,6 @@ 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