Register x19 (s3) is a callee-saved register. It must not be used to
load and jump to exported functions without saving it beforehand.
Replace it with t0, a temporary and caller-saved register.
Change the code comment to reflect this and fix it to correctly list gp
as the register with the pointer to global data.
Signed-off-by: Lukas Auer <lukas.a...@aisec.fraunhofer.de>
Reviewed-by: Bin Meng <bmeng...@gmail.com>
Tested-by: Bin Meng <bmeng...@gmail.com>
---
Changes in v2: None
examples/standalone/stubs.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/examples/standalone/stubs.c b/examples/standalone/stubs.c
index fadde669fa..f37d209da6 100644
--- a/examples/standalone/stubs.c
+++ b/examples/standalone/stubs.c
@@ -174,16 +174,16 @@ gd_t *global_data;
: : "i"(offsetof(gd_t, jt)), "i"(FO(x)) : "$r16");
#elif defined(CONFIG_RISCV)
/*
- * t7 holds the pointer to the global_data. gp is call clobbered.
+ * gp holds the pointer to the global_data. t0 is call clobbered.
*/
#define EXPORT_FUNC(f, a, x, ...) \
asm volatile ( \
" .globl " #x "\n" \
#x ":\n" \
-" lw x19, %0(gp)\n" \
-" lw x19, %1(x19)\n" \
-" jr x19\n" \
- : : "i"(offsetof(gd_t, jt)), "i"(FO(x)) : "x19");
+" lw t0, %0(gp)\n" \
+" lw t0, %1(t0)\n" \
+" jr t0\n" \
+ : : "i"(offsetof(gd_t, jt)), "i"(FO(x)) : "t0");
#elif defined(CONFIG_ARC)
/*
* r25 holds the pointer to the global_data. r10 is call clobbered.
--
2.20.1
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