[PATCH 1/3] arm: Fix software interrupt handler
Sean Anderson
sean.anderson at seco.com
Fri Oct 27 22:40:13 CEST 2023
When we take a software interrupt, we are already in supervisor mode.
get_bad_stack assumes we are not in supervisor mode so it can clobber
the stack pointer. This causes us to have an invalid stack once that
macro finishes. Revert back to the get_bad_stack_swi macro which was
previously removed.
Fixes: 41623c91b09 ("arm: move exception handling out of start.S files")
Signed-off-by: Sean Anderson <sean.anderson at seco.com>
---
arch/arm/lib/vectors.S | 14 +++++++++++++-
1 file changed, 13 insertions(+), 1 deletion(-)
diff --git a/arch/arm/lib/vectors.S b/arch/arm/lib/vectors.S
index 7cf7d1636f5..fe8ca403ac9 100644
--- a/arch/arm/lib/vectors.S
+++ b/arch/arm/lib/vectors.S
@@ -240,6 +240,18 @@ IRQ_STACK_START_IN:
movs pc, lr @ jump to next instruction & switch modes.
.endm
+ .macro get_bad_stack_swi
+ sub r13, r13, #4 @ space on current stack for scratch reg.
+ str r0, [r13] @ save R0's value.
+ ldr r0, IRQ_STACK_START_IN @ get data regions start
+ str lr, [r0] @ save caller lr in position 0 of saved stack
+ mrs lr, spsr @ get the spsr
+ str lr, [r0, #4] @ save spsr in position 1 of saved stack
+ ldr lr, [r0] @ restore lr
+ ldr r0, [r13] @ restore r0
+ add r13, r13, #4 @ pop stack entry
+ .endm
+
.macro get_irq_stack @ setup IRQ stack
ldr sp, IRQ_STACK_START
.endm
@@ -260,7 +272,7 @@ undefined_instruction:
.align 5
software_interrupt:
- get_bad_stack
+ get_bad_stack_swi
bad_save_user_regs
bl do_software_interrupt
--
2.35.1.1320.gc452695387.dirty
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