From: Will Deacon <will@kernel.org>
To: Sami Tolvanen <samitolvanen@google.com>
Cc: bpf@vger.kernel.org, Puranjay Mohan <puranjay@kernel.org>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Catalin Marinas <catalin.marinas@arm.com>,
Andrii Nakryiko <andrii@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, Maxwell Bland <mbland@motorola.com>,
Puranjay Mohan <puranjay12@gmail.com>,
Dao Huang <huangdao1@oppo.com>
Subject: Re: [PATCH bpf-next v10 3/3] arm64/cfi,bpf: Support kCFI + BPF on arm64
Date: Fri, 18 Jul 2025 12:42:54 +0100 [thread overview]
Message-ID: <aHozPj7NIudHmmgM@willie-the-truck> (raw)
In-Reply-To: <20250715225733.3921432-8-samitolvanen@google.com>
On Tue, Jul 15, 2025 at 10:57:37PM +0000, Sami Tolvanen wrote:
> From: Puranjay Mohan <puranjay12@gmail.com>
>
> Currently, bpf_dispatcher_*_func() is marked with `__nocfi` therefore
> calling BPF programs from this interface doesn't cause CFI warnings.
>
> When BPF programs are called directly from C: from BPF helpers or
> struct_ops, CFI warnings are generated.
>
> Implement proper CFI prologues for the BPF programs and callbacks and
> drop __nocfi for arm64. Fix the trampoline generation code to emit kCFI
> prologue when a struct_ops trampoline is being prepared.
>
> Signed-off-by: Puranjay Mohan <puranjay12@gmail.com>
> Co-developed-by: Maxwell Bland <mbland@motorola.com>
> Signed-off-by: Maxwell Bland <mbland@motorola.com>
> Co-developed-by: Sami Tolvanen <samitolvanen@google.com>
> Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
> Tested-by: Dao Huang <huangdao1@oppo.com>
> ---
> arch/arm64/include/asm/cfi.h | 7 +++++++
> arch/arm64/net/bpf_jit_comp.c | 22 +++++++++++++++++++---
> 2 files changed, 26 insertions(+), 3 deletions(-)
> create mode 100644 arch/arm64/include/asm/cfi.h
> diff --git a/arch/arm64/include/asm/cfi.h b/arch/arm64/include/asm/cfi.h
> new file mode 100644
> index 000000000000..ab90f0351b7a
> --- /dev/null
> +++ b/arch/arm64/include/asm/cfi.h
> @@ -0,0 +1,7 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef _ASM_ARM64_CFI_H
> +#define _ASM_ARM64_CFI_H
> +
> +#define __bpfcall
> +
> +#endif /* _ASM_ARM64_CFI_H */
So close to not needing the arch header at all!
Acked-by: Will Deacon <will@kernel.org>
Will
prev parent reply other threads:[~2025-07-18 12:43 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-07-15 22:57 [PATCH bpf-next v10 0/3] Support kCFI + BPF on arm64 Sami Tolvanen
2025-07-15 22:57 ` [PATCH bpf-next v10 1/3] cfi: add C CFI type macro Sami Tolvanen
2025-07-18 11:33 ` Will Deacon
2025-07-15 22:57 ` [PATCH bpf-next v10 2/3] cfi: Move BPF CFI types and helpers to generic code Sami Tolvanen
2025-07-18 11:39 ` Will Deacon
2025-07-18 22:27 ` Sami Tolvanen
2025-07-15 22:57 ` [PATCH bpf-next v10 3/3] arm64/cfi,bpf: Support kCFI + BPF on arm64 Sami Tolvanen
2025-07-18 11:42 ` Will Deacon [this message]
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