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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 3/7] bpf, arm64: Use resolved pointer for timed may_goto
Date: Fri,  4 Sep 2026 19:51:28 +0000	[thread overview]
Message-ID: <20260904195132.141068-4-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: 16175375da36 ("bpf, arm64: Add 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/arm64/net/bpf_timed_may_goto.S | 12 +++---------
 1 file changed, 3 insertions(+), 9 deletions(-)

diff --git a/arch/arm64/net/bpf_timed_may_goto.S b/arch/arm64/net/bpf_timed_may_goto.S
index a9a802711a7f..53148c9a1c58 100644
--- a/arch/arm64/net/bpf_timed_may_goto.S
+++ b/arch/arm64/net/bpf_timed_may_goto.S
@@ -14,16 +14,10 @@ SYM_FUNC_START(arch_bpf_timed_may_goto)
 	stp	x3, x4, [sp, #48]
 
 	/*
-	 * Stack depth was passed in BPF_REG_AX (x9), add it to the BPF_FP
-	 * (x25) to get the pointer to count and timestamp and pass it as the
-	 * first argument in x0.
-	 *
-	 * Before generating the call to arch_bpf_timed_may_goto, the verifier
-	 * generates a load instruction using FP, i.e. REG_AX = *(u64 *)(FP -
-	 * stack_off_cnt), so BPF_REG_FP (x25) is always set up by the arm64
-	 * jit in this case.
+	 * BPF_REG_AX (x9) contains the count and timestamp pointer; pass it as
+	 * the first argument in x0.
 	 */
-	add	x0, x9, x25
+	mov	x0, x9
 	bl	bpf_check_timed_may_goto
 	/* BPF_REG_AX(x9) will be stored into count, so move return value to it. */
 	mov	x9, x0
-- 
2.43.0

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WARNING: multiple messages have this Message-ID (diff)
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 3/7] bpf, arm64: Use resolved pointer for timed may_goto
Date: Fri,  4 Sep 2026 19:51:28 +0000	[thread overview]
Message-ID: <20260904195132.141068-4-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: 16175375da36 ("bpf, arm64: Add 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/arm64/net/bpf_timed_may_goto.S | 12 +++---------
 1 file changed, 3 insertions(+), 9 deletions(-)

diff --git a/arch/arm64/net/bpf_timed_may_goto.S b/arch/arm64/net/bpf_timed_may_goto.S
index a9a802711a7f..53148c9a1c58 100644
--- a/arch/arm64/net/bpf_timed_may_goto.S
+++ b/arch/arm64/net/bpf_timed_may_goto.S
@@ -14,16 +14,10 @@ SYM_FUNC_START(arch_bpf_timed_may_goto)
 	stp	x3, x4, [sp, #48]
 
 	/*
-	 * Stack depth was passed in BPF_REG_AX (x9), add it to the BPF_FP
-	 * (x25) to get the pointer to count and timestamp and pass it as the
-	 * first argument in x0.
-	 *
-	 * Before generating the call to arch_bpf_timed_may_goto, the verifier
-	 * generates a load instruction using FP, i.e. REG_AX = *(u64 *)(FP -
-	 * stack_off_cnt), so BPF_REG_FP (x25) is always set up by the arm64
-	 * jit in this case.
+	 * BPF_REG_AX (x9) contains the count and timestamp pointer; pass it as
+	 * the first argument in x0.
 	 */
-	add	x0, x9, x25
+	mov	x0, x9
 	bl	bpf_check_timed_may_goto
 	/* BPF_REG_AX(x9) will be stored into count, so move return value to it. */
 	mov	x9, x0
-- 
2.43.0

  parent reply	other threads:[~2026-09-04 19:51 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-09-04 19:51 [PATCH bpf-next v1 0/7] Fix timed may_goto with private stacks Siddharth Chintamaneni
2026-09-04 19:51 ` Siddharth Chintamaneni
2026-09-04 19:51 ` [PATCH bpf-next v1 1/7] bpf: Fix timed may_goto stack pointer for " Siddharth Chintamaneni
2026-09-04 19:51   ` Siddharth Chintamaneni
2026-09-04 19:58   ` sashiko-bot
2026-09-04 19:51 ` [PATCH bpf-next v1 2/7] bpf, x86: Use resolved pointer for timed may_goto Siddharth Chintamaneni
2026-09-04 19:51   ` Siddharth Chintamaneni
2026-09-04 20:02   ` sashiko-bot
2026-09-04 20:33   ` bot+bpf-ci
2026-09-04 20:33     ` bot+bpf-ci
2026-09-09 16:34     ` Siddharth Chintamaneni
2026-09-09 16:34       ` Siddharth Chintamaneni
2026-09-04 19:51 ` Siddharth Chintamaneni [this message]
2026-09-04 19:51   ` [PATCH bpf-next v1 3/7] bpf, arm64: " Siddharth Chintamaneni
2026-09-04 20:01   ` sashiko-bot
2026-09-04 19:51 ` [PATCH bpf-next v1 4/7] bpf, powerpc64: " Siddharth Chintamaneni
2026-09-04 19:51   ` Siddharth Chintamaneni
2026-09-04 19:58   ` sashiko-bot
2026-09-04 19:51 ` [PATCH bpf-next v1 5/7] bpf, riscv: " Siddharth Chintamaneni
2026-09-04 19:51   ` Siddharth Chintamaneni
2026-09-04 19:57   ` sashiko-bot
2026-09-04 20:33   ` bot+bpf-ci
2026-09-04 20:33     ` bot+bpf-ci
2026-09-04 19:51 ` [PATCH bpf-next v1 6/7] bpf, s390: " Siddharth Chintamaneni
2026-09-04 19:51   ` Siddharth Chintamaneni
2026-09-04 19:59   ` sashiko-bot
2026-09-04 20:33   ` bot+bpf-ci
2026-09-04 20:33     ` bot+bpf-ci
2026-09-04 19:51 ` [PATCH bpf-next v1 7/7] selftests/bpf: Test timed may_goto with private stacks Siddharth Chintamaneni
2026-09-04 19:51   ` Siddharth Chintamaneni
2026-09-04 19:58   ` sashiko-bot

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