diff options
| author | David Lechner <david@pybricks.com> | 2023-06-11 14:53:15 -0500 |
|---|---|---|
| committer | Damien George <damien@micropython.org> | 2023-06-14 17:43:44 +1000 |
| commit | b02a5fa10aba1b17c9a24a073992ded8d7031a69 (patch) | |
| tree | 71846d77304c8602fc373db03bed7ec613e9bee3 | |
| parent | 8cf9898dd3c93f3226d009ebce30f1f1c97b7afb (diff) | |
py/nlraarch64: Fix dangerous use of input register.
Starting with 2757acf6, the `top` variable in `nlr_jump()` in
`nlraarch64.c` was assigned to register `x19` by the compiler. However,
the assembly code writes over that register with
ldp x19, x20, [%0, #32]
since `%0` is now `x19`. This causes the next line
ldp lr, x9, [%0, #16]
to load the wrong values.
To fix the issue, we move the value of the `top` variable from an unknown
register to a known register at the beginning of the asm code then only use
known/hard-coded registers after that.
Fixes issue #11754.
Signed-off-by: David Lechner <david@pybricks.com>
| -rw-r--r-- | py/nlraarch64.c | 15 |
1 files changed, 8 insertions, 7 deletions
diff --git a/py/nlraarch64.c b/py/nlraarch64.c index 1295351cb..fcc318f2d 100644 --- a/py/nlraarch64.c +++ b/py/nlraarch64.c @@ -62,13 +62,14 @@ NORETURN void nlr_jump(void *val) { MP_STATIC_ASSERT(offsetof(nlr_buf_t, regs) == 16); // asm assumes it __asm volatile ( - "ldr x29, [%0, #112]\n" - "ldp x27, x28, [%0, #96]\n" - "ldp x25, x26, [%0, #80]\n" - "ldp x23, x24, [%0, #64]\n" - "ldp x21, x22, [%0, #48]\n" - "ldp x19, x20, [%0, #32]\n" - "ldp lr, x9, [%0, #16]\n" // 16 == offsetof(nlr_buf_t, regs) + "mov x0, %0 \n" + "ldr x29, [x0, #112]\n" + "ldp x27, x28, [x0, #96]\n" + "ldp x25, x26, [x0, #80]\n" + "ldp x23, x24, [x0, #64]\n" + "ldp x21, x22, [x0, #48]\n" + "ldp x19, x20, [x0, #32]\n" + "ldp lr, x9, [x0, #16]\n" // 16 == offsetof(nlr_buf_t, regs) "mov sp, x9 \n" "mov x0, #1 \n" // non-local return "ret \n" |