[PATCH bpf-next v1 5/7] bpf, riscv: Use resolved pointer for timed may_goto

From: Siddharth Chintamaneni <sidchintamaneni@gmail.com>
To: bpf@vger.kernel.org
Cc: Siddharth Chintamaneni <sidchintamaneni@gmail.com>,
	Jeremy Jean <jeremy.jean@oss.cyber.gouv.fr>,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	John Fastabend <john.fastabend@gmail.com>,
	Andrii Nakryiko <andrii@kernel.org>,
	Eduard Zingerman <eddyz87@gmail.com>,
	Kumar Kartikeya Dwivedi <memxor@gmail.com>,
	Martin KaFai Lau <martin.lau@linux.dev>,
	Song Liu <song@kernel.org>,
	Yonghong Song <yonghong.song@linux.dev>,
	Jiri Olsa <jolsa@kernel.org>,
	Emil Tsalapatis <emil@etsalapatis.com>,
	Ihor Solodrai <ihor.solodrai@linux.dev>,
	Anton Protopopov <a.s.protopopov@gmail.com>,
	Puranjay Mohan <puranjay@kernel.org>,
	linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org,
	linux-riscv@lists.infradead.org, rlmenge@gmail.com,
	hargar@linux.microsoft.com, apais@microsoft.com
Subject: [PATCH bpf-next v1 5/7] bpf, riscv: Use resolved pointer for timed may_goto
Date: Fri,  4 Sep 2026 19:51:30 +0000	[thread overview]
Message-ID: <20260904195132.141068-6-sidchintamaneni@gmail.com> (raw)
In-Reply-To: <20260904195132.141068-1-sidchintamaneni@gmail.com>

The timed may_goto fixup now passes the resolved counter pointer through
BPF_REG_AX instead of a stack offset.

Copy the pointer directly into the first argument register rather than
adding it to the BPF frame pointer again.

Fixes: 6ef8ff20c30b ("bpf, riscv: Add 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/riscv/net/bpf_timed_may_goto.S | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/arch/riscv/net/bpf_timed_may_goto.S b/arch/riscv/net/bpf_timed_may_goto.S
index 02c637d87420..8c03e272e0bf 100644
--- a/arch/riscv/net/bpf_timed_may_goto.S
+++ b/arch/riscv/net/bpf_timed_may_goto.S
@@ -6,12 +6,11 @@
 
 /*
  * Trampoline for the BPF timed may_goto loop bound. Custom calling convention:
- *	- input:  stack offset in BPF_REG_AX (t0)
+ *	- input:  count and timestamp pointer in BPF_REG_AX (t0)
  *	- output: updated count in BPF_REG_AX (t0)
  *
- * Calls bpf_check_timed_may_goto(ptr) with the standard RISC-V ABI, where
- * ptr = BPF_REG_FP (s5) + BPF_REG_AX (t0). BPF R0-R5 (a5, a0-a4) are saved
- * across the call; BPF_REG_FP (s5) is callee-saved and needs no saving.
+ * Calls bpf_check_timed_may_goto(ptr) with the standard RISC-V ABI.
+ * BPF R0-R5 (a5, a0-a4) are saved across the call.
  */
 
 SYM_FUNC_START(arch_bpf_timed_may_goto)
@@ -28,7 +27,11 @@ SYM_FUNC_START(arch_bpf_timed_may_goto)
 	REG_S	a3, 1*SZREG(sp)
 	REG_S	a4, 0*SZREG(sp)
 
-	add	a0, t0, s5
+	/*
+	 * BPF_REG_AX (t0) contains the count and timestamp pointer; pass it as
+	 * the first argument in a0.
+	 */
+	mv	a0, t0
 	call	bpf_check_timed_may_goto
 	mv	t0, a0
 
-- 
2.43.0

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