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From: "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>
To: Alexander Gordeev <agordeev@linux.ibm.com>,
	Andrii Nakryiko <andrii.nakryiko@gmail.com>,
	Alexei Starovoitov <ast@kernel.org>,
	Christian Borntraeger <borntraeger@linux.ibm.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Vasily Gorbik <gor@linux.ibm.com>,
	Heiko Carstens <hca@linux.ibm.com>,
	Ilya Leoshkevich <iii@linux.ibm.com>,
	Michael Ellerman <mpe@ellerman.id.au>,
	Paul Walmsley <paul.walmsley@sifive.com>
Cc: bpf@vger.kernel.org
Subject: Re: [PATCH bpf-next v3 04/11] libbpf: Add __PT_PARM1_REG_SYSCALL macro
Date: Fri, 04 Feb 2022 16:15:56 +0000	[thread overview]
Message-ID: <1643990954.fs9q9mrdxt.naveen@linux.ibm.com> (raw)
In-Reply-To: <20220204145018.1983773-5-iii@linux.ibm.com>

Ilya Leoshkevich wrote:
> Some architectures have a special way to access the first syscall
> argument. There already exists __PT_PARM4_REG_SYSCALL for the
> fourth argument, so define a similar macro for the first one.
> 
> Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
> ---
>  tools/lib/bpf/bpf_tracing.h | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/tools/lib/bpf/bpf_tracing.h b/tools/lib/bpf/bpf_tracing.h
> index 032ba809f3e5..30f0964f8c9e 100644
> --- a/tools/lib/bpf/bpf_tracing.h
> +++ b/tools/lib/bpf/bpf_tracing.h
> @@ -265,7 +265,11 @@ struct pt_regs;
> 
>  #endif
> 
> +#ifdef __PT_PARM1_REG_SYSCALL
> +#define PT_REGS_PARM1_SYSCALL(x) (__PT_REGS_CAST(x)->__PT_PARM1_REG_SYSCALL)
> +#else /* __PT_PARM1_REG_SYSCALL */
>  #define PT_REGS_PARM1_SYSCALL(x) PT_REGS_PARM1(x)
> +#endif
>  #define PT_REGS_PARM2_SYSCALL(x) PT_REGS_PARM2(x)
>  #define PT_REGS_PARM3_SYSCALL(x) PT_REGS_PARM3(x)
>  #ifdef __PT_PARM4_REG_SYSCALL
> @@ -275,7 +279,11 @@ struct pt_regs;
>  #endif
>  #define PT_REGS_PARM5_SYSCALL(x) PT_REGS_PARM5(x)
> 
> +#ifdef __PT_PARM1_REG_SYSCALL
> +#define PT_REGS_PARM1_CORE_SYSCALL(x) BPF_CORE_READ(__PT_REGS_CAST(x), __PT_PARM1_REG_SYSCALL)
> +#else /* __PT_PARM1_REG_SYSCALL */
>  #define PT_REGS_PARM1_CORE_SYSCALL(x) PT_REGS_PARM1_CORE(x)
> +#endif
>  #define PT_REGS_PARM2_CORE_SYSCALL(x) PT_REGS_PARM2_CORE(x)
>  #define PT_REGS_PARM3_CORE_SYSCALL(x) PT_REGS_PARM3_CORE(x)
>  #ifdef __PT_PARM4_REG_SYSCALL

When I was contemplating implementing this for powerpc, I came up with 
the below patch which looked cleaner to me, and also makes it easy for 
architectures to over-ride any other syscall parameter in future. Feel 
free to include this in your series if it makes sense.

- Naveen

--
libbpf: Generalize overriding syscall parameter access macros

Instead of conditionally overriding PT_REGS_PARM4_SYSCALL, provide
default fallback for all _REG_SYSCALL macros so that architectures can
simply override a specific syscall parameter macro.

Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
---
 tools/lib/bpf/bpf_tracing.h | 40 ++++++++++++++++++++++---------------
 1 file changed, 24 insertions(+), 16 deletions(-)

diff --git a/tools/lib/bpf/bpf_tracing.h b/tools/lib/bpf/bpf_tracing.h
index 032ba809f3e57a..2e2f057c7ec7c5 100644
--- a/tools/lib/bpf/bpf_tracing.h
+++ b/tools/lib/bpf/bpf_tracing.h
@@ -265,25 +265,33 @@ struct pt_regs;
 
 #endif
 
-#define PT_REGS_PARM1_SYSCALL(x) PT_REGS_PARM1(x)
-#define PT_REGS_PARM2_SYSCALL(x) PT_REGS_PARM2(x)
-#define PT_REGS_PARM3_SYSCALL(x) PT_REGS_PARM3(x)
-#ifdef __PT_PARM4_REG_SYSCALL
-#define PT_REGS_PARM4_SYSCALL(x) (__PT_REGS_CAST(x)->__PT_PARM4_REG_SYSCALL)
-#else /* __PT_PARM4_REG_SYSCALL */
-#define PT_REGS_PARM4_SYSCALL(x) PT_REGS_PARM4(x)
+#ifndef __PT_PARM1_REG_SYSCALL
+#define __PT_PARM1_REG_SYSCALL __PT_PARM1_REG
+#endif
+#ifndef __PT_PARM2_REG_SYSCALL
+#define __PT_PARM2_REG_SYSCALL __PT_PARM2_REG
+#endif
+#ifndef __PT_PARM3_REG_SYSCALL
+#define __PT_PARM3_REG_SYSCALL __PT_PARM3_REG
+#endif
+#ifndef __PT_PARM4_REG_SYSCALL
+#define __PT_PARM4_REG_SYSCALL __PT_PARM4_REG
 #endif
-#define PT_REGS_PARM5_SYSCALL(x) PT_REGS_PARM5(x)
+#ifndef __PT_PARM5_REG_SYSCALL
+#define __PT_PARM5_REG_SYSCALL __PT_PARM5_REG
+#endif
+
+#define PT_REGS_PARM1_SYSCALL(x) (__PT_REGS_CAST(x)->__PT_PARM1_REG_SYSCALL)
+#define PT_REGS_PARM2_SYSCALL(x) (__PT_REGS_CAST(x)->__PT_PARM2_REG_SYSCALL)
+#define PT_REGS_PARM3_SYSCALL(x) (__PT_REGS_CAST(x)->__PT_PARM3_REG_SYSCALL)
+#define PT_REGS_PARM4_SYSCALL(x) (__PT_REGS_CAST(x)->__PT_PARM4_REG_SYSCALL)
+#define PT_REGS_PARM5_SYSCALL(x) (__PT_REGS_CAST(x)->__PT_PARM5_REG_SYSCALL)
 
-#define PT_REGS_PARM1_CORE_SYSCALL(x) PT_REGS_PARM1_CORE(x)
-#define PT_REGS_PARM2_CORE_SYSCALL(x) PT_REGS_PARM2_CORE(x)
-#define PT_REGS_PARM3_CORE_SYSCALL(x) PT_REGS_PARM3_CORE(x)
-#ifdef __PT_PARM4_REG_SYSCALL
+#define PT_REGS_PARM1_CORE_SYSCALL(x) BPF_CORE_READ(__PT_REGS_CAST(x), __PT_PARM1_REG_SYSCALL)
+#define PT_REGS_PARM2_CORE_SYSCALL(x) BPF_CORE_READ(__PT_REGS_CAST(x), __PT_PARM2_REG_SYSCALL)
+#define PT_REGS_PARM3_CORE_SYSCALL(x) BPF_CORE_READ(__PT_REGS_CAST(x), __PT_PARM3_REG_SYSCALL)
 #define PT_REGS_PARM4_CORE_SYSCALL(x) BPF_CORE_READ(__PT_REGS_CAST(x), __PT_PARM4_REG_SYSCALL)
-#else /* __PT_PARM4_REG_SYSCALL */
-#define PT_REGS_PARM4_CORE_SYSCALL(x) PT_REGS_PARM4_CORE(x)
-#endif
-#define PT_REGS_PARM5_CORE_SYSCALL(x) PT_REGS_PARM5_CORE(x)
+#define PT_REGS_PARM5_CORE_SYSCALL(x) BPF_CORE_READ(__PT_REGS_CAST(x), __PT_PARM5_REG_SYSCALL)
 
 #else /* defined(bpf_target_defined) */
 
-- 
2.34.1



  reply	other threads:[~2022-02-04 16:16 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-02-04 14:50 [PATCH bpf-next v3 00/11] libbpf: Fix accessing syscall arguments Ilya Leoshkevich
2022-02-04 14:50 ` [PATCH bpf-next v3 01/11] arm64/bpf: Add orig_x0 to user_pt_regs Ilya Leoshkevich
2022-02-04 14:50 ` [PATCH bpf-next v3 02/11] s390/bpf: Add orig_gpr2 " Ilya Leoshkevich
2022-02-05  0:36   ` Heiko Carstens
2022-02-05 12:37   ` Vasily Gorbik
2022-02-04 14:50 ` [PATCH bpf-next v3 03/11] selftests/bpf: Fix an endianness issue in bpf_syscall_macro test Ilya Leoshkevich
2022-02-04 14:50 ` [PATCH bpf-next v3 04/11] libbpf: Add __PT_PARM1_REG_SYSCALL macro Ilya Leoshkevich
2022-02-04 16:15   ` Naveen N. Rao [this message]
2022-02-04 14:50 ` [PATCH bpf-next v3 05/11] libbpf: Add PT_REGS_SYSCALL_REGS macro Ilya Leoshkevich
2022-02-04 16:46   ` Naveen N. Rao
2022-02-04 18:15     ` Andrii Nakryiko
2022-02-05  7:04       ` Naveen N. Rao
2022-02-04 14:50 ` [PATCH bpf-next v3 06/11] selftests/bpf: Use PT_REGS_SYSCALL_REGS in bpf_syscall_macro Ilya Leoshkevich
2022-02-04 14:50 ` [PATCH bpf-next v3 07/11] libbpf: Fix accessing the first syscall argument on arm64 Ilya Leoshkevich
2022-02-04 14:50 ` [PATCH bpf-next v3 08/11] libbpf: Fix accessing syscall arguments on powerpc Ilya Leoshkevich
2022-02-05  7:05   ` Naveen N. Rao
2022-02-04 14:50 ` [PATCH bpf-next v3 09/11] libbpf: Fix accessing program counter on riscv Ilya Leoshkevich
2022-02-04 14:50 ` [PATCH bpf-next v3 10/11] libbpf: Fix accessing syscall arguments " Ilya Leoshkevich
2022-02-04 14:50 ` [PATCH bpf-next v3 11/11] libbpf: Fix accessing the first syscall argument on s390 Ilya Leoshkevich
2022-02-05 20:30 ` [PATCH bpf-next v3 00/11] libbpf: Fix accessing syscall arguments patchwork-bot+netdevbpf
2022-02-07 16:10   ` Andrii Nakryiko

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