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From: Menglong Dong <menglong8.dong@gmail.com>
To: ast@kernel.org, bjorn@kernel.org
Cc: daniel@iogearbox.net, andrii@kernel.org, martin.lau@linux.dev,
	eddyz87@gmail.com, song@kernel.org, yonghong.song@linux.dev,
	john.fastabend@gmail.com, kpsingh@kernel.org, sdf@fomichev.me,
	haoluo@google.com, jolsa@kernel.org, pulehui@huawei.com,
	puranjay@kernel.org, pjw@kernel.org, palmer@dabbelt.com,
	aou@eecs.berkeley.edu, alex@ghiti.fr, bpf@vger.kernel.org,
	linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
	jiang.biao@linux.dev
Subject: [PATCH bpf-next v4 1/3] bpf, riscv: introduce emit_store_stack_imm64() for trampoline
Date: Sun,  8 Feb 2026 13:33:09 +0800	[thread overview]
Message-ID: <20260208053311.698352-2-dongml2@chinatelecom.cn> (raw)
In-Reply-To: <20260208053311.698352-1-dongml2@chinatelecom.cn>

Introduce a helper to store 64-bit immediate on the trampoline stack with
a help of a register.

Signed-off-by: Menglong Dong <dongml2@chinatelecom.cn>
Tested-by: Björn Töpel <bjorn@kernel.org>
Acked-by: Björn Töpel <bjorn@kernel.org>
---
 arch/riscv/net/bpf_jit_comp64.c | 25 ++++++++++++++-----------
 1 file changed, 14 insertions(+), 11 deletions(-)

diff --git a/arch/riscv/net/bpf_jit_comp64.c b/arch/riscv/net/bpf_jit_comp64.c
index 37888abee70c..e4f45e2e7e2f 100644
--- a/arch/riscv/net/bpf_jit_comp64.c
+++ b/arch/riscv/net/bpf_jit_comp64.c
@@ -926,6 +926,14 @@ static void restore_stack_args(int nr_stack_args, int args_off, int stk_arg_off,
 	}
 }
 
+static void emit_store_stack_imm64(u8 reg, int stack_off, u64 imm64,
+				   struct rv_jit_context *ctx)
+{
+	/* Load imm64 into reg and store it at [FP + stack_off]. */
+	emit_imm(reg, (s64)imm64, ctx);
+	emit_sd(RV_REG_FP, stack_off, reg, ctx);
+}
+
 static int invoke_bpf_prog(struct bpf_tramp_link *l, int args_off, int retval_off,
 			   int run_ctx_off, bool save_ret, struct rv_jit_context *ctx)
 {
@@ -933,12 +941,10 @@ static int invoke_bpf_prog(struct bpf_tramp_link *l, int args_off, int retval_of
 	struct bpf_prog *p = l->link.prog;
 	int cookie_off = offsetof(struct bpf_tramp_run_ctx, bpf_cookie);
 
-	if (l->cookie) {
-		emit_imm(RV_REG_T1, l->cookie, ctx);
-		emit_sd(RV_REG_FP, -run_ctx_off + cookie_off, RV_REG_T1, ctx);
-	} else {
+	if (l->cookie)
+		emit_store_stack_imm64(RV_REG_T1, -run_ctx_off + cookie_off, l->cookie, ctx);
+	else
 		emit_sd(RV_REG_FP, -run_ctx_off + cookie_off, RV_REG_ZERO, ctx);
-	}
 
 	/* arg1: prog */
 	emit_imm(RV_REG_A0, (const s64)p, ctx);
@@ -1123,13 +1129,10 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im,
 	emit_sd(RV_REG_FP, -sreg_off, RV_REG_S1, ctx);
 
 	/* store ip address of the traced function */
-	if (flags & BPF_TRAMP_F_IP_ARG) {
-		emit_imm(RV_REG_T1, (const s64)func_addr, ctx);
-		emit_sd(RV_REG_FP, -ip_off, RV_REG_T1, ctx);
-	}
+	if (flags & BPF_TRAMP_F_IP_ARG)
+		emit_store_stack_imm64(RV_REG_T1, -ip_off, (u64)func_addr, ctx);
 
-	emit_li(RV_REG_T1, nr_arg_slots, ctx);
-	emit_sd(RV_REG_FP, -nregs_off, RV_REG_T1, ctx);
+	emit_store_stack_imm64(RV_REG_T1, -nregs_off, nr_arg_slots, ctx);
 
 	store_args(nr_arg_slots, args_off, ctx);
 
-- 
2.53.0


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  reply	other threads:[~2026-02-08  5:33 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-02-08  5:33 [PATCH bpf-next v4 0/3] bpf: fsession support for riscv Menglong Dong
2026-02-08  5:33 ` Menglong Dong [this message]
2026-02-08  5:33 ` [PATCH bpf-next v4 2/3] bpf, riscv: add fsession support for trampolines Menglong Dong
2026-02-08  5:33 ` [PATCH bpf-next v4 3/3] selftests/bpf: enable fsession_test on riscv64 Menglong Dong
2026-02-09 13:18 ` [PATCH bpf-next v4 0/3] bpf: fsession support for riscv Pu Lehui
2026-02-11 21:30 ` patchwork-bot+netdevbpf
2026-03-24  6:07 ` patchwork-bot+linux-riscv

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