[PATCH bpf-next v1 6/7] bpf, s390: Use resolved pointer for timed may_goto

[Siddharth Chintamaneni <sidchintamaneni@gmail.com>]

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 <jeremy.jean@oss.cyber.gouv.fr>
Link: https://lore.kernel.org/all/20260824213158.3755932-2-Jeremy.Jean@oss.cyber.gouv.fr/
Assisted-by: Copilot:gpt-5.6-sol
Signed-off-by: Siddharth Chintamaneni <sidchintamaneni@gmail.com>
---
 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