diff options
author | Naveen N Rao <naveen@kernel.org> | 2024-10-30 12:38:42 +0530 |
---|---|---|
committer | Michael Ellerman <mpe@ellerman.id.au> | 2024-10-31 11:00:54 +1100 |
commit | 9670f6d2097c4f97e15c67920dfddc664d7ee91c (patch) | |
tree | 603f43532a9698c1f7a513b4551848fd551f6241 /arch/powerpc | |
parent | ed6144656bb1ea29ad83671b48a21c89e7873b8a (diff) |
powerpc64/bpf: Fold bpf_jit_emit_func_call_hlp() into bpf_jit_emit_func_call_rel()
Commit 61688a82e047 ("powerpc/bpf: enable kfunc call") enhanced
bpf_jit_emit_func_call_hlp() to handle calls out to module region, where
bpf progs are generated. The only difference now between
bpf_jit_emit_func_call_hlp() and bpf_jit_emit_func_call_rel() is in
handling of the initial pass where target function address is not known.
Fold that logic into bpf_jit_emit_func_call_hlp() and rename it to
bpf_jit_emit_func_call_rel() to simplify bpf function call JIT code.
We don't actually need to load/restore TOC across a call out to a
different kernel helper or to a different bpf program since they all
work with the kernel TOC. We only need to do it if we have to call out
to a module function. So, guard TOC load/restore with appropriate
conditions.
Signed-off-by: Naveen N Rao <naveen@kernel.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://patch.msgid.link/20241030070850.1361304-10-hbathini@linux.ibm.com
Diffstat (limited to 'arch/powerpc')
-rw-r--r-- | arch/powerpc/net/bpf_jit_comp64.c | 61 |
1 files changed, 17 insertions, 44 deletions
diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c index 2cbcdf93cc19..f3be024fc685 100644 --- a/arch/powerpc/net/bpf_jit_comp64.c +++ b/arch/powerpc/net/bpf_jit_comp64.c @@ -202,14 +202,22 @@ void bpf_jit_build_epilogue(u32 *image, struct codegen_context *ctx) EMIT(PPC_RAW_BLR()); } -static int -bpf_jit_emit_func_call_hlp(u32 *image, u32 *fimage, struct codegen_context *ctx, u64 func) +int bpf_jit_emit_func_call_rel(u32 *image, u32 *fimage, struct codegen_context *ctx, u64 func) { unsigned long func_addr = func ? ppc_function_entry((void *)func) : 0; long reladdr; - if (WARN_ON_ONCE(!kernel_text_address(func_addr))) - return -EINVAL; + /* bpf to bpf call, func is not known in the initial pass. Emit 5 nops as a placeholder */ + if (!func) { + for (int i = 0; i < 5; i++) + EMIT(PPC_RAW_NOP()); + /* elfv1 needs an additional instruction to load addr from descriptor */ + if (IS_ENABLED(CONFIG_PPC64_ELF_ABI_V1)) + EMIT(PPC_RAW_NOP()); + EMIT(PPC_RAW_MTCTR(_R12)); + EMIT(PPC_RAW_BCTRL()); + return 0; + } #ifdef CONFIG_PPC_KERNEL_PCREL reladdr = func_addr - local_paca->kernelbase; @@ -266,7 +274,8 @@ bpf_jit_emit_func_call_hlp(u32 *image, u32 *fimage, struct codegen_context *ctx, * We can clobber r2 since we get called through a * function pointer (so caller will save/restore r2). */ - EMIT(PPC_RAW_LD(_R2, bpf_to_ppc(TMP_REG_2), 8)); + if (is_module_text_address(func_addr)) + EMIT(PPC_RAW_LD(_R2, bpf_to_ppc(TMP_REG_2), 8)); } else { PPC_LI64(_R12, func); EMIT(PPC_RAW_MTCTR(_R12)); @@ -276,46 +285,14 @@ bpf_jit_emit_func_call_hlp(u32 *image, u32 *fimage, struct codegen_context *ctx, * Load r2 with kernel TOC as kernel TOC is used if function address falls * within core kernel text. */ - EMIT(PPC_RAW_LD(_R2, _R13, offsetof(struct paca_struct, kernel_toc))); + if (is_module_text_address(func_addr)) + EMIT(PPC_RAW_LD(_R2, _R13, offsetof(struct paca_struct, kernel_toc))); } #endif return 0; } -int bpf_jit_emit_func_call_rel(u32 *image, u32 *fimage, struct codegen_context *ctx, u64 func) -{ - unsigned int i, ctx_idx = ctx->idx; - - if (WARN_ON_ONCE(func && is_module_text_address(func))) - return -EINVAL; - - /* skip past descriptor if elf v1 */ - func += FUNCTION_DESCR_SIZE; - - /* Load function address into r12 */ - PPC_LI64(_R12, func); - - /* For bpf-to-bpf function calls, the callee's address is unknown - * until the last extra pass. As seen above, we use PPC_LI64() to - * load the callee's address, but this may optimize the number of - * instructions required based on the nature of the address. - * - * Since we don't want the number of instructions emitted to increase, - * we pad the optimized PPC_LI64() call with NOPs to guarantee that - * we always have a five-instruction sequence, which is the maximum - * that PPC_LI64() can emit. - */ - if (!image) - for (i = ctx->idx - ctx_idx; i < 5; i++) - EMIT(PPC_RAW_NOP()); - - EMIT(PPC_RAW_MTCTR(_R12)); - EMIT(PPC_RAW_BCTRL()); - - return 0; -} - static int bpf_jit_emit_tail_call(u32 *image, struct codegen_context *ctx, u32 out) { /* @@ -1102,11 +1079,7 @@ emit_clear: if (ret < 0) return ret; - if (func_addr_fixed) - ret = bpf_jit_emit_func_call_hlp(image, fimage, ctx, func_addr); - else - ret = bpf_jit_emit_func_call_rel(image, fimage, ctx, func_addr); - + ret = bpf_jit_emit_func_call_rel(image, fimage, ctx, func_addr); if (ret) return ret; |