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Message-ID: <841804f7-d634-4d8c-8585-04a2e4ea40f0@linux.ibm.com>
Date: Tue, 29 Oct 2024 12:14:30 +0530
From: Hari Bathini <hbathini@...ux.ibm.com>
To: Michael Ellerman <mpe@...erman.id.au>,
linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>, bpf@...r.kernel.org,
linux-trace-kernel@...r.kernel.org, linux-kbuild@...r.kernel.org,
linux-kernel@...r.kernel.org
Cc: "Naveen N. Rao" <naveen@...nel.org>, Mark Rutland <mark.rutland@....com>,
Daniel Borkmann <daniel@...earbox.net>,
Masahiro Yamada <masahiroy@...nel.org>,
Nicholas Piggin <npiggin@...il.com>,
Alexei Starovoitov <ast@...nel.org>,
Steven Rostedt <rostedt@...dmis.org>,
Masami Hiramatsu <mhiramat@...nel.org>,
Andrii Nakryiko <andrii@...nel.org>,
Christophe Leroy <christophe.leroy@...roup.eu>,
Vishal Chourasia <vishalc@...ux.ibm.com>,
Mahesh J Salgaonkar <mahesh@...ux.ibm.com>
Subject: Re: [PATCH v6 17/17] powerpc64/bpf: Add support for bpf trampolines
On 28/10/24 7:53 am, Michael Ellerman wrote:
> Hari Bathini <hbathini@...ux.ibm.com> writes:
>> From: Naveen N Rao <naveen@...nel.org>
>>
>> Add support for bpf_arch_text_poke() and arch_prepare_bpf_trampoline()
>> for 64-bit powerpc. While the code is generic, BPF trampolines are only
>> enabled on 64-bit powerpc. 32-bit powerpc will need testing and some
>> updates.
>
> Hi Hari,
>
> This is breaking the PCREL build for me:
>
> ERROR: 11:49:18: Failed building ppc64le_defconfig+pcrel@...ora
> INFO: 11:49:18: (skipped 41 lines) ...
> INFO: 11:49:18: /linux/arch/powerpc/net/bpf_jit.h:90:9: note: in expansion of macro 'EMIT'
> 90 | EMIT(PPC_RAW_LD(_R2, _R13, offsetof(struct paca_struct, kernel_toc)))
> | ^~~~
> /linux/arch/powerpc/include/asm/ppc-opcode.h:473:88: note: in expansion of macro 'IMM_DS'
> 473 | #define PPC_RAW_LD(r, base, i) (0xe8000000 | ___PPC_RT(r) | ___PPC_RA(base) | IMM_DS(i))
> | ^~~~~~
> /linux/arch/powerpc/net/bpf_jit.h:90:14: note: in expansion of macro 'PPC_RAW_LD'
> 90 | EMIT(PPC_RAW_LD(_R2, _R13, offsetof(struct paca_struct, kernel_toc)))
> | ^~~~~~~~~~
> /linux/arch/powerpc/net/bpf_jit.h:90:36: note: in expansion of macro 'offsetof'
> 90 | EMIT(PPC_RAW_LD(_R2, _R13, offsetof(struct paca_struct, kernel_toc)))
> | ^~~~~~~~
> /linux/arch/powerpc/net/bpf_jit_comp.c:791:17: note: in expansion of macro 'PPC64_LOAD_PACA'
> 791 | PPC64_LOAD_PACA();
> | ^~~~~~~~~~~~~~~
> /linux/arch/powerpc/net/bpf_jit.h:90:65: error: 'struct paca_struct' has no member named 'kernel_toc'; did you mean 'kernel_msr'?
> 90 | EMIT(PPC_RAW_LD(_R2, _R13, offsetof(struct paca_struct, kernel_toc)))
> | ^~~~~~~~~~
> /linux/arch/powerpc/net/bpf_jit.h:29:34: note: in definition of macro 'PLANT_INSTR'
> 29 | do { if (d) { (d)[idx] = instr; } idx++; } while (0)
> | ^~~~~
> /linux/arch/powerpc/net/bpf_jit.h:90:9: note: in expansion of macro 'EMIT'
> 90 | EMIT(PPC_RAW_LD(_R2, _R13, offsetof(struct paca_struct, kernel_toc)))
> | ^~~~
> /linux/arch/powerpc/include/asm/ppc-opcode.h:473:88: note: in expansion of macro 'IMM_DS'
> 473 | #define PPC_RAW_LD(r, base, i) (0xe8000000 | ___PPC_RT(r) | ___PPC_RA(base) | IMM_DS(i))
> | ^~~~~~
> /linux/arch/powerpc/net/bpf_jit.h:90:14: note: in expansion of macro 'PPC_RAW_LD'
> 90 | EMIT(PPC_RAW_LD(_R2, _R13, offsetof(struct paca_struct, kernel_toc)))
> | ^~~~~~~~~~
> /linux/arch/powerpc/net/bpf_jit.h:90:36: note: in expansion of macro 'offsetof'
> 90 | EMIT(PPC_RAW_LD(_R2, _R13, offsetof(struct paca_struct, kernel_toc)))
> | ^~~~~~~~
> /linux/arch/powerpc/net/bpf_jit_comp.c:882:25: note: in expansion of macro 'PPC64_LOAD_PACA'
> 882 | PPC64_LOAD_PACA();
> | ^~~~~~~~~~~~~~~
> make[5]: *** [/linux/scripts/Makefile.build:229: arch/powerpc/net/bpf_jit_comp.o] Error 1
>
>
> To test it you need to enable CONFIG_POWER10_CPU, eg:
>
> CONFIG_POWERPC64_CPU=n
> CONFIG_POWER10_CPU=y
> CONFIG_PPC_KERNEL_PCREL=y
>
> This diff gets it building, but I haven't tested it actually works:
Thanks, Michael. Yeah, the below snippet will be sufficient as
PPC64_LOAD_PACA() is used with !IS_ENABLED(CONFIG_PPC_KERNEL_PCREL)
- Hari
> diff --git a/arch/powerpc/net/bpf_jit.h b/arch/powerpc/net/bpf_jit.h
> index 2d04ce5a23da..af6ff3eb621a 100644
> --- a/arch/powerpc/net/bpf_jit.h
> +++ b/arch/powerpc/net/bpf_jit.h
> @@ -86,9 +86,14 @@
> 0xffff)); \
> } } while (0)
> #define PPC_LI_ADDR PPC_LI64
> +
> +#ifndef CONFIG_PPC_KERNEL_PCREL
> #define PPC64_LOAD_PACA() \
> EMIT(PPC_RAW_LD(_R2, _R13, offsetof(struct paca_struct, kernel_toc)))
> #else
> +#define PPC64_LOAD_PACA() do {} while (0)
> +#endif
> +#else
> #define PPC_LI64(d, i) BUILD_BUG()
> #define PPC_LI_ADDR PPC_LI32
> #define PPC64_LOAD_PACA() BUILD_BUG()
>
> cheers
>
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