The timed may_goto fixup now passes the resolved counter pointer through
BPF_REG_AX instead of a stack offset and BPF frame pointer pair.
Copy the pointer directly into the first argument register and update the
special calling convention documentation.
Fixes: b8efa810c1db ("s390/bpf: Add s390 JIT support for timed may_goto")
Reported-by: Jeremy Jean <[email protected]>
Link:
https://lore.kernel.org/all/[email protected]/
Assisted-by: Copilot:gpt-5.6-sol
Signed-off-by: Siddharth Chintamaneni <[email protected]>
---
arch/s390/net/bpf_jit_comp.c | 6 +++---
arch/s390/net/bpf_timed_may_goto.S | 8 ++++----
2 files changed, 7 insertions(+), 7 deletions(-)
diff --git a/arch/s390/net/bpf_jit_comp.c b/arch/s390/net/bpf_jit_comp.c
index c46872b071ce..4098c3377c21 100644
--- a/arch/s390/net/bpf_jit_comp.c
+++ b/arch/s390/net/bpf_jit_comp.c
@@ -1872,9 +1872,9 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit,
struct bpf_prog *fp,
if ((void *)func == arch_bpf_timed_may_goto) {
/*
* arch_bpf_timed_may_goto() has a special ABI: the
- * parameters are in BPF_REG_AX and BPF_REG_10; the
- * return value is in BPF_REG_AX; and all GPRs except
- * REG_W0, REG_W1, and BPF_REG_AX are callee-saved.
+ * parameter and return value are in BPF_REG_AX; all
+ * GPRs except REG_W0, REG_W1, and BPF_REG_AX are
+ * callee-saved.
*/
/* brasl %r0,func */
diff --git a/arch/s390/net/bpf_timed_may_goto.S
b/arch/s390/net/bpf_timed_may_goto.S
index 06f567a460d7..e34c99982c4a 100644
--- a/arch/s390/net/bpf_timed_may_goto.S
+++ b/arch/s390/net/bpf_timed_may_goto.S
@@ -21,9 +21,9 @@
SYM_FUNC_START(arch_bpf_timed_may_goto)
/*
- * This function has a special ABI: the parameters are in %r12 and
- * %r13; the return value is in %r12; all GPRs except %r0, %r1, and
- * %r12 are callee-saved; and the return address is in %r0.
+ * This function has a special ABI: the parameter and return value are
+ * in %r12; all GPRs except %r0, %r1, and %r12 are callee-saved; and
+ * the return address is in %r0.
*/
stmg %r2,%r5,FRAME_OFF+R2_OFF(%r15)
stg %r14,FRAME_OFF+R14_OFF(%r15)
@@ -33,7 +33,7 @@ SYM_FUNC_START(arch_bpf_timed_may_goto)
lay %r15,-FRAME_SIZE(%r15)
stg %r1,__SF_BACKCHAIN(%r15)
- lay %r2,0(%r12,%r13)
+ lgr %r2,%r12
brasl %r14,bpf_check_timed_may_goto
lgr %r12,%r2
--
2.43.0
