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-rw-r--r--arch/arc/include/asm/entry-arcv2.h361
1 files changed, 190 insertions, 171 deletions
diff --git a/arch/arc/include/asm/entry-arcv2.h b/arch/arc/include/asm/entry-arcv2.h
index 225e7df2d8ed..f5ae394ebe06 100644
--- a/arch/arc/include/asm/entry-arcv2.h
+++ b/arch/arc/include/asm/entry-arcv2.h
@@ -7,232 +7,251 @@
#include <asm/irqflags-arcv2.h>
#include <asm/thread_info.h> /* For THREAD_SIZE */
+/*
+ * Interrupt/Exception stack layout (pt_regs) for ARCv2
+ * (End of struct aligned to end of page [unless nested])
+ *
+ * INTERRUPT EXCEPTION
+ *
+ * manual --------------------- manual
+ * | orig_r0 |
+ * | event/ECR |
+ * | bta |
+ * | user_r25 |
+ * | gp |
+ * | fp |
+ * | sp |
+ * | r12 |
+ * | r30 |
+ * | r58 |
+ * | r59 |
+ * hw autosave ---------------------
+ * optional | r0 |
+ * | r1 |
+ * ~ ~
+ * | r9 |
+ * | r10 |
+ * | r11 |
+ * | blink |
+ * | lpe |
+ * | lps |
+ * | lpc |
+ * | ei base |
+ * | ldi base |
+ * | jli base |
+ * ---------------------
+ * hw autosave | pc / eret |
+ * mandatory | stat32 / erstatus |
+ * ---------------------
+ */
+
/*------------------------------------------------------------------------*/
-.macro INTERRUPT_PROLOGUE called_from
+.macro INTERRUPT_PROLOGUE
- ; Before jumping to Interrupt Vector, hardware micro-ops did following:
+ ; (A) Before jumping to Interrupt Vector, hardware micro-ops did following:
; 1. SP auto-switched to kernel mode stack
- ; 2. STATUS32.Z flag set to U mode at time of interrupt (U:1, K:0)
- ; 3. Auto saved: r0-r11, blink, LPE,LPS,LPC, JLI,LDI,EI, PC, STAT32
+ ; 2. STATUS32.Z flag set if in U mode at time of interrupt (U:1,K:0)
+ ; 3. Auto save: (mandatory) Push PC and STAT32 on stack
+ ; hardware does even if CONFIG_ARC_IRQ_NO_AUTOSAVE
+ ; 4. Auto save: (optional) r0-r11, blink, LPE,LPS,LPC, JLI,LDI,EI
;
- ; Now manually save: r12, sp, fp, gp, r25
+ ; (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
+
+ ; OUTPUT: r10 has ECR expected by EV_Trap
+.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
; - U mode: retrieve it from AUX_USER_SP
; - K mode: add the offset from current SP where H/w starts auto push
;
- ; Utilize the fact that Z bit is set if Intr taken in U mode
- mov.nz r9, sp
- add.nz r9, r9, SZ_PT_REGS - PT_sp - 4
- bnz 1f
+ ; 1. Utilize the fact that Z bit is set if Intr taken in U mode
+ ; 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]
-1:
- PUSH r9 ; SP
+ lr r10, [AUX_USER_SP] ; U 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 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
-.ifnc \called_from, exception
- add sp, sp, 12 ; skip BTA/ECR/orig_r0 placeholderss
-.endif
+ LD2 gp, fp, PT_r26 ; gp (r26), fp (r27)
-#ifdef CONFIG_ARC_CURR_IN_REG
- POP r25
-#else
- add sp, sp, 4
-#endif
+ ld r12, [sp, PT_sp + 4]
+ ld r30, [sp, PT_sp + 8]
- POP gp
- POP fp
-
- ; Don't touch AUX_USER_SP if returning to K mode (Z bit set)
- ; (Z bit set on K mode is inverse of INTERRUPT_PROLOGUE)
- add.z sp, sp, 4
+ ; Restore SP (into AUX_USER_SP) only if returning to U mode
+ ; - for K mode, it will be implicitly restored as stack is unwound
+ ; - Z flag set on K is inverse of what hardware does on interrupt entry
+ ; 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 __RESTORE_REGFILE_HARD
+
+ ld blink, [sp, PT_blink]
+
+ LD2 r10, r11, PT_lpe
+ sr r10, [lp_end]
+ sr r11, [lp_start]
+
+ ld r10, [sp, PT_lpc] ; lp_count can't be target of LD
+ mov lp_count, 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
+
/*------------------------------------------------------------------------*/
-.macro EXCEPTION_PROLOGUE
+.macro INTERRUPT_EPILOGUE
- ; Before jumping to Exception Vector, hardware micro-ops did following:
- ; 1. SP auto-switched to kernel mode stack
- ; 2. STATUS32.Z flag set to U mode at time of interrupt (U:1,K:0)
- ;
- ; Now manually save the complete reg file
-
- PUSH r9 ; freeup a register: slot of erstatus
-
- PUSHAX eret
- sub sp, sp, 12 ; skip JLI, LDI, EI
- PUSH lp_count
- PUSHAX lp_start
- PUSHAX lp_end
- PUSH blink
-
- PUSH r11
- PUSH r10
-
- 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
-
- ; -- 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)
- ;
- ; Set Z flag if this was from U mode (expected by INTERRUPT_PROLOGUE)
- ; Although H/w exception micro-ops do set Z flag for U mode (just like
- ; for interrupts), it could get clobbered in case we soft land here from
- ; a TLB Miss exception handler (tlbex.S)
+ ; INPUT: r0 has STAT32 of calling context
+ ; INPUT: Z flag set if returning to K mode
- and r10, r10, STATUS_U_MASK
- xor.f 0, r10, STATUS_U_MASK
+ ; _SOFT clobbers r10 restored by _HARD hence the order
- INTERRUPT_PROLOGUE exception
+ __RESTORE_REGFILE_SOFT
- PUSHAX erbta
- PUSHAX ecr ; r9 contains ECR, expected by EV_Trap
+#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
.endm
/*------------------------------------------------------------------------*/
.macro EXCEPTION_EPILOGUE
- ; Assumes r0 has PT_status32
- 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
+ ; INPUT: r0 has STAT32 of calling context
- POP r0
- POP r1
- POP r2
- POP r3
- POP r4
- POP r5
- POP r6
- POP r7
- POP r8
- POP r9
- POP r10
- POP r11
+ btst r0, STATUS_U_BIT ; Z flag set if K, used in restoring SP
- POP blink
- POPAX lp_end
- POPAX lp_start
+ ld r10, [sp, PT_event + 4]
+ sr r10, [erbta]
- POP r9
- mov lp_count, r9
+ LD2 r10, r11, PT_ret
+ sr r10, [eret]
+ sr r11, [erstatus]
- add sp, sp, 12 ; skip JLI, LDI, EI
- POPAX eret
- POPAX erstatus
+ __RESTORE_REGFILE_SOFT
+ __RESTORE_REGFILE_HARD
- ld.as r9, [sp, -12] ; reload r9 which got clobbered
+ add sp, sp, SZ_PT_REGS
.endm
.macro FAKE_RET_FROM_EXCPN
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.