On 28/10/24 7:53 am, Michael Ellerman wrote:
Hari Bathini <hbathini@xxxxxxxxxxxxx> writes:
From: Naveen N Rao <naveen@xxxxxxxxxx>
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
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
