diff options
Diffstat (limited to 'arch/arm')
| -rw-r--r-- | arch/arm/cpu/armv8/exceptions.S | 132 |
1 files changed, 82 insertions, 50 deletions
diff --git a/arch/arm/cpu/armv8/exceptions.S b/arch/arm/cpu/armv8/exceptions.S index 1a78a5d1dc..a15af72e02 100644 --- a/arch/arm/cpu/armv8/exceptions.S +++ b/arch/arm/cpu/armv8/exceptions.S @@ -11,7 +11,26 @@ #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 @@ -22,52 +41,9 @@ 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]! @@ -84,7 +60,19 @@ _exception_entry: 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 @@ -100,16 +88,36 @@ _exception_entry: 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 @@ -126,3 +134,27 @@ exception_exit: 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 |