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authorAmaury Pouly <amaury.pouly@gmail.com>2016-09-21 00:09:23 +0100
committerAmaury Pouly <amaury.pouly@gmail.com>2016-12-12 13:17:33 +0100
commita523c3fcfe40734f3b15fbf086578fa188fc0ec6 (patch)
tree2e0a9c880b9df4675d856328e68cf7c16a961391 /firmware/target/arm/imx233/icoll-imx233.c
parent7e0820fe21247d528f4c3483822af4f4a66571ee (diff)
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imx233: fix IRQ handler w.r.t unwinder
The IRQ handler saves registers on the IRQ stack, saves the old PC to imx233 HW_DIGCTL_SCRATCH0 register and switcht to SVC for the actual handling. The old code had a problem in that if the unwinder is called during the IRQ (for example by the watchdog), then __get_sp() will use SPSR_svc to discover the previous mode, switch to it and recover SP. But SPSR_svc is invalid, it should be SPSR_irq but we switch from IRQ to SVC mode. The new code copies SPSR_irq to SPSR_svc in IRQ to fix this problem. It also saves/restore SCRATCH0 in case I one day renable nested interrupts or use SCRATCH0 for other purposes. I also changed the old watchdog code to call UIE directly instead of trying to make the code crash with a SWI. Change-Id: Id87462d410764b019bd2aa9adc71cb917ade32e3
Diffstat (limited to 'firmware/target/arm/imx233/icoll-imx233.c')
-rw-r--r--firmware/target/arm/imx233/icoll-imx233.c17
1 files changed, 12 insertions, 5 deletions
diff --git a/firmware/target/arm/imx233/icoll-imx233.c b/firmware/target/arm/imx233/icoll-imx233.c
index 3dff41394f..d5c6e48a89 100644
--- a/firmware/target/arm/imx233/icoll-imx233.c
+++ b/firmware/target/arm/imx233/icoll-imx233.c
@@ -205,13 +205,17 @@ void irq_handler(void)
{
/* save stuff */
asm volatile(
+ /* This part is in IRQ mode (with IRQ stack) */
"sub lr, lr, #4 \n" /* Create return address */
"stmfd sp!, { r0-r5, r12, lr } \n" /* Save what gets clobbered */
- "ldr r1, =0x8001c290 \n" /* Save pointer to instruction */
- "str lr, [r1] \n" /* in HW_DIGCTL_SCRATCH0 */
- "mrs lr, spsr \n" /* Save SPSR_irq */
- "stmfd sp!, { r1, lr } \n" /* Push it on the stack */
+ "ldr r1, =0x8001c290 \n" /* Save HW_DIGCTL_SCRATCH0 */
+ "ldr r0, [r1] \n" /* and store instruction pointer */
+ "str lr, [r1] \n" /* in it (for debug) */
+ "mrs r2, spsr \n" /* Save SPSR_irq */
+ "stmfd sp!, { r0, r2 } \n" /* Push it on the stack */
"msr cpsr_c, #0x93 \n" /* Switch to SVC mode, IRQ disabled */
+ /* This part is in SVC mode (with SVC stack) */
+ "msr spsr_cxsf, r2 \n" /* Copy SPSR_irq to SPSR_svc (for __get_sp) */
"mov r4, lr \n" /* Save lr_SVC */
"and r5, sp, #4 \n" /* Align SVC stack */
"sub sp, sp, r5 \n" /* on 8-byte boundary */
@@ -219,7 +223,10 @@ void irq_handler(void)
"add sp, sp, r5 \n" /* Undo alignement */
"mov lr, r4 \n" /* Restore lr_SVC */
"msr cpsr_c, #0x92 \n" /* Mask IRQ, return to IRQ mode */
- "ldmfd sp!, { r1, lr } \n" /* Reload saved value */
+ /* This part is in IRQ mode (with IRQ stack) */
+ "ldmfd sp!, { r0, lr } \n" /* Reload saved value */
+ "ldr r1, =0x8001c290 \n" /* Restore HW_DIGCTL_SCRATCH0 */
+ "str r0, [r1] \n" /* using saved value */
"msr spsr_cxsf, lr \n" /* Restore SPSR_irq */
"ldmfd sp!, { r0-r5, r12, pc }^ \n" /* Restore regs, and RFE */);
}