Re: [PATCH v6 17/17] powerpc64/bpf: Add support for bpf trampolines
From: Hari Bathini <hbathini@linux.ibm.com>
Date: 2024-10-29 06:45:38
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bpf, linux-kbuild, linux-trace-kernel, lkml
On 28/10/24 7:53 am, Michael Ellerman wrote:
Hari Bathini [off-list ref] writes:quoted
From: Naveen N Rao <naveen@kernel.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@fedora 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
quoted hunk ↗ jump to hunk
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