#include <linux/linkage.h>
/*
- * Exception vectors.
+ * AArch64 exception vectors:
+ * We have four types of exceptions:
+ * - synchronous: traps, data aborts, undefined instructions, ...
+ * - IRQ: group 1 (normal) interrupts
+ * - FIQ: group 0 or secure interrupts
+ * - SError: fatal system errors
+ * There are entries for all four of those for different contexts:
+ * - from same exception level, when using the SP_EL0 stack pointer
+ * - from same exception level, when using the SP_ELx stack pointer
+ * - from lower exception level, when this is AArch64
+ * - from lower exception level, when this is AArch32
+ * Each of those 16 entries have space for 32 instructions, each entry must
+ * be 128 byte aligned, the whole table must be 2K aligned.
+ * The 32 instructions are not enough to save and restore all registers and
+ * to branch to the actual handler, so we split this up:
+ * Each entry saves the LR, branches to the save routine, then to the actual
+ * handler, then to the restore routine. The save and restore routines are
+ * each split in half and stuffed in the unused gap between the entries.
+ * Also as we do not run anything in a lower exception level, we just provide
+ * the first 8 entries for exceptions from the same EL.
*/
.align 11
.globl vectors
bl do_bad_sync
b exception_exit
- .align 7 /* Current EL IRQ Thread */
- stp x29, x30, [sp, #-16]!
- bl _exception_entry
- bl do_bad_irq
- b exception_exit
-
- .align 7 /* Current EL FIQ Thread */
- stp x29, x30, [sp, #-16]!
- bl _exception_entry
- bl do_bad_fiq
- b exception_exit
-
- .align 7 /* Current EL Error Thread */
- stp x29, x30, [sp, #-16]!
- bl _exception_entry
- bl do_bad_error
- b exception_exit
-
- .align 7 /* Current EL Synchronous Handler */
- stp x29, x30, [sp, #-16]!
- bl _exception_entry
- bl do_sync
- b exception_exit
-
- .align 7 /* Current EL IRQ Handler */
- stp x29, x30, [sp, #-16]!
- bl _exception_entry
- bl do_irq
- b exception_exit
-
- .align 7 /* Current EL FIQ Handler */
- stp x29, x30, [sp, #-16]!
- bl _exception_entry
- bl do_fiq
- b exception_exit
-
- .align 7 /* Current EL Error Handler */
- stp x29, x30, [sp, #-16]!
- bl _exception_entry
- bl do_error
- b exception_exit
-
/*
- * Enter Exception.
- * This will save the processor state that is ELR/X0~X30
- * to the stack frame.
+ * Save (most of) the GP registers to the stack frame.
+ * This is the first part of the shared routine called into from all entries.
*/
_exception_entry:
stp x27, x28, [sp, #-16]!
stp x5, x6, [sp, #-16]!
stp x3, x4, [sp, #-16]!
stp x1, x2, [sp, #-16]!
+ b _save_el_regs /* jump to the second part */
+ .align 7 /* Current EL IRQ Thread */
+ stp x29, x30, [sp, #-16]!
+ bl _exception_entry
+ bl do_bad_irq
+ b exception_exit
+
+/*
+ * Save exception specific context: ESR and ELR, for all exception levels.
+ * This is the second part of the shared routine called into from all entries.
+ */
+_save_el_regs:
/* Could be running at EL3/EL2/EL1 */
switch_el x11, 3f, 2f, 1f
3: mrs x1, esr_el3
mov x0, sp
ret
-
+ .align 7 /* Current EL FIQ Thread */
+ stp x29, x30, [sp, #-16]!
+ bl _exception_entry
+ bl do_bad_fiq
+ /* falling through to _exception_exit */
+/*
+ * Restore the exception return address, for all exception levels.
+ * This is the first part of the shared routine called into from all entries.
+ */
exception_exit:
ldp x2, x0, [sp],#16
switch_el x11, 3f, 2f, 1f
3: msr elr_el3, x2
- b 0f
+ b _restore_regs
2: msr elr_el2, x2
- b 0f
+ b _restore_regs
1: msr elr_el1, x2
-0:
+ b _restore_regs /* jump to the second part */
+
+ .align 7 /* Current EL Error Thread */
+ stp x29, x30, [sp, #-16]!
+ bl _exception_entry
+ bl do_bad_error
+ b exception_exit
+
+/*
+ * Restore the general purpose registers from the exception stack, then return.
+ * This is the second part of the shared routine called into from all entries.
+ */
+_restore_regs:
ldp x1, x2, [sp],#16
ldp x3, x4, [sp],#16
ldp x5, x6, [sp],#16
ldp x27, x28, [sp],#16
ldp x29, x30, [sp],#16
eret
+
+ .align 7 /* Current EL (SP_ELx) Synchronous Handler */
+ stp x29, x30, [sp, #-16]!
+ bl _exception_entry
+ bl do_sync
+ b exception_exit
+
+ .align 7 /* Current EL (SP_ELx) IRQ Handler */
+ stp x29, x30, [sp, #-16]!
+ bl _exception_entry
+ bl do_irq
+ b exception_exit
+
+ .align 7 /* Current EL (SP_ELx) FIQ Handler */
+ stp x29, x30, [sp, #-16]!
+ bl _exception_entry
+ bl do_fiq
+ b exception_exit
+
+ .align 7 /* Current EL (SP_ELx) Error Handler */
+ stp x29, x30, [sp, #-16]!
+ bl _exception_entry
+ bl do_error
+ b exception_exit
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