Signed-off-by: Vineet Gupta <vgupta@xxxxxxxxxxxx> --- arch/arc/include/asm/entry-arcv2.h | 78 ++++++++++++++++++++++++++++++-------- 1 file changed, 62 insertions(+), 16 deletions(-) diff --git a/arch/arc/include/asm/entry-arcv2.h b/arch/arc/include/asm/entry-arcv2.h index 225e7df2d8ed..1c3520d1fa42 100644 --- a/arch/arc/include/asm/entry-arcv2.h +++ b/arch/arc/include/asm/entry-arcv2.h @@ -7,15 +7,54 @@ #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 - - ; 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 @@ -57,14 +96,17 @@ ; - 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 + ; 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 + mov.nz r9, sp - add.nz r9, r9, SZ_PT_REGS - PT_sp - 4 + add.nz r9, r9, SZ_PT_REGS - PT_sp - 4 ; K mode SP bnz 1f - lr r9, [AUX_USER_SP] + lr r9, [AUX_USER_SP] ; U mode SP 1: - PUSH r9 ; SP + PUSH r9 ; SP (pt_regs->sp) PUSH fp PUSH gp @@ -85,6 +127,8 @@ /*------------------------------------------------------------------------*/ .macro INTERRUPT_EPILOGUE called_from + ; 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 @@ -98,9 +142,10 @@ 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 @@ -145,11 +190,11 @@ /*------------------------------------------------------------------------*/ .macro EXCEPTION_PROLOGUE - ; Before jumping to Exception Vector, hardware micro-ops did following: + ; (A) 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) + ; 2. STATUS32.Z flag set if in U mode at time of exception (U:1,K:0) ; - ; Now manually save the complete reg file + ; (B) Manually save the complete reg file below PUSH r9 ; freeup a register: slot of erstatus @@ -195,12 +240,13 @@ PUSHAX ecr ; r9 contains ECR, expected by EV_Trap PUSH r0 ; orig_r0 + ; OUTPUT: r9 has ECR .endm /*------------------------------------------------------------------------*/ .macro EXCEPTION_EPILOGUE - ; Assumes r0 has PT_status32 + ; 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 -- 2.7.4 _______________________________________________ linux-snps-arc mailing list linux-snps-arc@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/linux-snps-arc
