authorgravatar for alex@alexrp.comAlex Rønne Petersen <alex@alexrp.com> 2026-08-08 03:19:47+02:00
committergravatar for alex@alexrp.comAlex Rønne Petersen <alex@alexrp.com> 2026-08-09 16:56:23+02:00
log2a155d75ac575c9a99918569249aecdf251e94d9
tree652a6ece86825633cb47541434b024773fda2f68
parent3b947932abbb9f14710c64e3afa6fa88947d1ed1
signaturebadge-check Signed by SSH key SHA256:7B/LJ7bpR1eX8aCXSr4mtd5M45VMPKcx9zY8e95b5QM

std: fix stack alignment in or1k _start and clone assembly

l.andi zero-extends its operand so this would give the wrong result. Instead, use l.addi to materialize -4 and then l.and that. Rather unfortunate that the assembler doesn't reject this form.

2 files changed, 4 insertions(+), 2 deletions(-)

lib/std/os/linux/or1k.zig+2-1
......@@ -124,7 +124,8 @@ pub fn clone() callconv(.naked) u32 {
124124 // r11 r3, r4, r5, r6, r7
125125 asm volatile (
126126 \\ # Save function pointer and argument pointer on new thread stack
127 \\ l.andi r4, r4, -4
127 \\ l.addi r13, r0, -4
128 \\ l.and r4, r4, r13
128129 \\ l.addi r4, r4, -8
129130 \\ l.sw 0(r4), r3
130131 \\ l.sw 4(r4), r6
lib/std/start.zig+2-1
......@@ -326,7 +326,8 @@ fn _start() callconv(.naked) noreturn {
326326 \\ l.ori r2, r0, 0
327327 \\ l.ori r9, r0, 0
328328 \\ l.ori r3, r1, 0
329 \\ l.andi r1, r1, -4
329 \\ l.addi r13, r0, -4
330 \\ l.and r1, r1, r13
330331 \\ l.j %[posixCallMainAndExit]
331332 \\ l.nop
332333 ,