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-rw-r--r--src/arch/riscv/trap_util.S12
1 files changed, 8 insertions, 4 deletions
diff --git a/src/arch/riscv/trap_util.S b/src/arch/riscv/trap_util.S
index 44cfab7c99..5582a0770c 100644
--- a/src/arch/riscv/trap_util.S
+++ b/src/arch/riscv/trap_util.S
@@ -128,10 +128,14 @@ trap_entry:
.Lsmp_hang:
bnez sp, .Lsmp_hang
- # TODO: Use the old stack pointer (plus an offset) for exceptions in machine
- # mode, to avoid overwriting stack data.
- la sp, _estack
- addi sp,sp,-MENTRY_FRAME_SIZE
+ # Use a different stack than in the main context, to to avoid overwriting
+ # stack data.
+ # TODO: Maybe use the old stack pointer (plus an offset) instead. But only if
+ # the previous mode was M, because it would be a very bad idea to use a stack
+ # pointer provided by unprivileged code!
+ la sp, _estack
+ addi sp, sp, -2048 # 2 KiB is half of the stack space
+ addi sp, sp, -MENTRY_FRAME_SIZE
save_tf
move a0,sp