| Message ID | 20240201171249.253097-1-hbathini@linux.ibm.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Headers | show |
| Series | [v2,1/2] powerpc/bpf: ensure module addresses are supported | expand |
Le 01/02/2024 à 18:12, Hari Bathini a écrit : > Currently, bpf jit code on powerpc assumes all the bpf functions and > helpers to be kernel text. This is false for kfunc case, as function > addresses are mostly module addresses in that case. Ensure module > addresses are supported to enable kfunc support. > > Assume kernel text address for programs with no kfunc call to optimize > instruction sequence in that case. Add a check to error out if this > assumption ever changes in the future. > > Signed-off-by: Hari Bathini <hbathini@linux.ibm.com> > --- > > Changes in v2: > * Using bpf_prog_has_kfunc_call() to decide whether to use optimized > instruction sequence or not as suggested by Naveen. > > > arch/powerpc/net/bpf_jit.h | 5 +- > arch/powerpc/net/bpf_jit_comp.c | 4 +- > arch/powerpc/net/bpf_jit_comp32.c | 8 ++- > arch/powerpc/net/bpf_jit_comp64.c | 109 ++++++++++++++++++++++++------ > 4 files changed, 97 insertions(+), 29 deletions(-) > > diff --git a/arch/powerpc/net/bpf_jit.h b/arch/powerpc/net/bpf_jit.h > index cdea5dccaefe..fc56ee0ee9c5 100644 > --- a/arch/powerpc/net/bpf_jit.h > +++ b/arch/powerpc/net/bpf_jit.h > @@ -160,10 +160,11 @@ static inline void bpf_clear_seen_register(struct codegen_context *ctx, int i) > } > > void bpf_jit_init_reg_mapping(struct codegen_context *ctx); > -int bpf_jit_emit_func_call_rel(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, > + bool has_kfunc_call); > int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct codegen_context *ctx, > u32 *addrs, int pass, bool extra_pass); > -void bpf_jit_build_prologue(u32 *image, struct codegen_context *ctx); > +void bpf_jit_build_prologue(u32 *image, struct codegen_context *ctx, bool has_kfunc_call); > void bpf_jit_build_epilogue(u32 *image, struct codegen_context *ctx); > void bpf_jit_realloc_regs(struct codegen_context *ctx); > int bpf_jit_emit_exit_insn(u32 *image, struct codegen_context *ctx, int tmp_reg, long exit_addr); > diff --git a/arch/powerpc/net/bpf_jit_comp.c b/arch/powerpc/net/bpf_jit_comp.c > index 0f9a21783329..7b4103b4c929 100644 > --- a/arch/powerpc/net/bpf_jit_comp.c > +++ b/arch/powerpc/net/bpf_jit_comp.c > @@ -163,7 +163,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp) > * update ctgtx.idx as it pretends to output instructions, then we can > * calculate total size from idx. > */ > - bpf_jit_build_prologue(NULL, &cgctx); > + bpf_jit_build_prologue(NULL, &cgctx, bpf_prog_has_kfunc_call(fp)); > addrs[fp->len] = cgctx.idx * 4; > bpf_jit_build_epilogue(NULL, &cgctx); > > @@ -192,7 +192,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp) > /* Now build the prologue, body code & epilogue for real. */ > cgctx.idx = 0; > cgctx.alt_exit_addr = 0; > - bpf_jit_build_prologue(code_base, &cgctx); > + bpf_jit_build_prologue(code_base, &cgctx, bpf_prog_has_kfunc_call(fp)); > if (bpf_jit_build_body(fp, code_base, fcode_base, &cgctx, addrs, pass, > extra_pass)) { > bpf_arch_text_copy(&fhdr->size, &hdr->size, sizeof(hdr->size)); > diff --git a/arch/powerpc/net/bpf_jit_comp32.c b/arch/powerpc/net/bpf_jit_comp32.c > index 2f39c50ca729..447747e51a58 100644 > --- a/arch/powerpc/net/bpf_jit_comp32.c > +++ b/arch/powerpc/net/bpf_jit_comp32.c > @@ -123,7 +123,7 @@ void bpf_jit_realloc_regs(struct codegen_context *ctx) > } > } > > -void bpf_jit_build_prologue(u32 *image, struct codegen_context *ctx) > +void bpf_jit_build_prologue(u32 *image, struct codegen_context *ctx, bool has_kfunc_call) > { > int i; > > @@ -201,7 +201,8 @@ void bpf_jit_build_epilogue(u32 *image, struct codegen_context *ctx) > } > > /* Relative offset needs to be calculated based on final image location */ > -int bpf_jit_emit_func_call_rel(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, > + bool has_kfunc_call) > { > s32 rel = (s32)func - (s32)(fimage + ctx->idx); > > @@ -1054,7 +1055,8 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct code > EMIT(PPC_RAW_STW(bpf_to_ppc(BPF_REG_5), _R1, 12)); > } > > - ret = bpf_jit_emit_func_call_rel(image, fimage, ctx, func_addr); > + ret = bpf_jit_emit_func_call_rel(image, fimage, ctx, func_addr, > + bpf_prog_has_kfunc_call(fp)); > if (ret) > return ret; > > diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c > index 79f23974a320..385a5df1670c 100644 > --- a/arch/powerpc/net/bpf_jit_comp64.c > +++ b/arch/powerpc/net/bpf_jit_comp64.c > @@ -122,12 +122,17 @@ void bpf_jit_realloc_regs(struct codegen_context *ctx) > { > } > > -void bpf_jit_build_prologue(u32 *image, struct codegen_context *ctx) > +void bpf_jit_build_prologue(u32 *image, struct codegen_context *ctx, bool has_kfunc_call) > { > int i; > > #ifndef CONFIG_PPC_KERNEL_PCREL > - if (IS_ENABLED(CONFIG_PPC64_ELF_ABI_V2)) > + /* > + * If the program doesn't have a kfunc call, all BPF helpers are part of kernel text > + * and all BPF programs/functions utilize the kernel TOC. So, optimize the > + * instruction sequence by using kernel toc in r2 for that case. > + */ > + if (!has_kfunc_call && IS_ENABLED(CONFIG_PPC64_ELF_ABI_V2)) > EMIT(PPC_RAW_LD(_R2, _R13, offsetof(struct paca_struct, kernel_toc))); > #endif > > @@ -202,12 +207,17 @@ 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, struct codegen_context *ctx, u64 func) > +static int bpf_jit_emit_func_call_hlp(u32 *image, struct codegen_context *ctx, u64 func, > + bool has_kfunc_call) > { > unsigned long func_addr = func ? ppc_function_entry((void *)func) : 0; > long reladdr; > > - if (WARN_ON_ONCE(!core_kernel_text(func_addr))) > + /* > + * If the program doesn't have a kfunc call, all BPF helpers are assumed to be part of > + * kernel text. Don't proceed if that assumption ever changes in future. > + */ > + if (!has_kfunc_call && WARN_ON_ONCE(!core_kernel_text(func_addr))) > return -EINVAL; > > if (IS_ENABLED(CONFIG_PPC_KERNEL_PCREL)) { > @@ -225,30 +235,55 @@ static int bpf_jit_emit_func_call_hlp(u32 *image, struct codegen_context *ctx, u > EMIT(PPC_RAW_BCTR()); > > } else { > - reladdr = func_addr - kernel_toc_addr(); > - if (reladdr > 0x7FFFFFFF || reladdr < -(0x80000000L)) { > - pr_err("eBPF: address of %ps out of range of kernel_toc.\n", (void *)func); > - return -ERANGE; > - } > + if (has_kfunc_call) { > +#ifdef PPC64_ELF_ABI_v1 I can't see a reason for a #ifdef here, why not use IS_ENABLED() like other places ? > + /* func points to the function descriptor */ > + PPC_LI64(b2p[TMP_REG_2], func); > + /* Load actual entry point from function descriptor */ > + PPC_BPF_LL(b2p[TMP_REG_1], b2p[TMP_REG_2], 0); > + /* ... and move it to CTR */ > + EMIT(PPC_RAW_MTCTR(b2p[TMP_REG_1])); > + /* > + * Load TOC from function descriptor at offset 8. > + * We can clobber r2 since we get called through a > + * function pointer (so caller will save/restore r2) > + * and since we don't use a TOC ourself. > + */ > + PPC_BPF_LL(2, b2p[TMP_REG_2], 8); > +#else > + /* We can clobber r12 */ > + PPC_LI64(12, func); > + EMIT(PPC_RAW_MTCTR(12)); > +#endif > + } else { > + reladdr = func_addr - kernel_toc_addr(); > + if (reladdr > 0x7FFFFFFF || reladdr < -(0x80000000L)) { > + pr_err("eBPF: address of %ps out of range of kernel_toc.\n", > + (void *)func); > + return -ERANGE; > + } > > - EMIT(PPC_RAW_ADDIS(_R12, _R2, PPC_HA(reladdr))); > - EMIT(PPC_RAW_ADDI(_R12, _R12, PPC_LO(reladdr))); > - EMIT(PPC_RAW_MTCTR(_R12)); > + EMIT(PPC_RAW_ADDIS(_R12, _R2, PPC_HA(reladdr))); > + EMIT(PPC_RAW_ADDI(_R12, _R12, PPC_LO(reladdr))); > + EMIT(PPC_RAW_MTCTR(_R12)); > + } > EMIT(PPC_RAW_BCTRL()); > } > > return 0; > } > > -int bpf_jit_emit_func_call_rel(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, > + bool has_kfunc_call) > { > unsigned int i, ctx_idx = ctx->idx; > > - if (WARN_ON_ONCE(func && is_module_text_address(func))) > + if (WARN_ON_ONCE(func && !has_kfunc_call && is_module_text_address(func))) > return -EINVAL; > > /* skip past descriptor if elf v1 */ > - func += FUNCTION_DESCR_SIZE; > + if (!has_kfunc_call) > + func += FUNCTION_DESCR_SIZE; > > /* Load function address into r12 */ > PPC_LI64(_R12, func); > @@ -267,13 +302,28 @@ int bpf_jit_emit_func_call_rel(u32 *image, u32 *fimage, struct codegen_context * > for (i = ctx->idx - ctx_idx; i < 5; i++) > EMIT(PPC_RAW_NOP()); > > +#ifdef PPC64_ELF_ABI_v1 I can't see a reason for a #ifdef here, why not use IS_ENABLED() like other places ? > + if (has_kfunc_call) { > + /* > + * Load TOC from function descriptor at offset 8. > + * We can clobber r2 since we get called through a > + * function pointer (so caller will save/restore r2) > + * and since we don't use a TOC ourself. > + */ > + PPC_BPF_LL(2, 12, 8); > + /* Load actual entry point from function descriptor */ > + PPC_BPF_LL(12, 12, 0); > + } > +#endif > + > 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) > +static int bpf_jit_emit_tail_call(u32 *image, struct codegen_context *ctx, u32 out, > + bool has_kfunc_call) > { > /* > * By now, the eBPF program has already setup parameters in r3, r4 and r5 > @@ -285,7 +335,7 @@ static int bpf_jit_emit_tail_call(u32 *image, struct codegen_context *ctx, u32 o > int b2p_index = bpf_to_ppc(BPF_REG_3); > int bpf_tailcall_prologue_size = 8; > > - if (IS_ENABLED(CONFIG_PPC64_ELF_ABI_V2)) > + if (!has_kfunc_call && IS_ENABLED(CONFIG_PPC64_ELF_ABI_V2)) > bpf_tailcall_prologue_size += 4; /* skip past the toc load */ > > /* > @@ -325,8 +375,20 @@ static int bpf_jit_emit_tail_call(u32 *image, struct codegen_context *ctx, u32 o > > /* goto *(prog->bpf_func + prologue_size); */ > EMIT(PPC_RAW_LD(bpf_to_ppc(TMP_REG_1), bpf_to_ppc(TMP_REG_1), offsetof(struct bpf_prog, bpf_func))); > - EMIT(PPC_RAW_ADDI(bpf_to_ppc(TMP_REG_1), bpf_to_ppc(TMP_REG_1), > - FUNCTION_DESCR_SIZE + bpf_tailcall_prologue_size)); > + if (has_kfunc_call) { > +#ifdef PPC64_ELF_ABI_v1 I can't see a reason for a #ifdef here, why not use IS_ENABLED() like other places ? > + /* skip past the function descriptor */ > + EMIT(PPC_RAW_ADDI(bpf_to_ppc(TMP_REG_1), bpf_to_ppc(TMP_REG_1), > + FUNCTION_DESCR_SIZE + bpf_tailcall_prologue_size)); > +#else > + EMIT(PPC_RAW_ADDI(bpf_to_ppc(TMP_REG_1), bpf_to_ppc(TMP_REG_1), > + bpf_tailcall_prologue_size)); > +#endif > + } else { > + EMIT(PPC_RAW_ADDI(bpf_to_ppc(TMP_REG_1), bpf_to_ppc(TMP_REG_1), > + FUNCTION_DESCR_SIZE + bpf_tailcall_prologue_size)); > + } > + > EMIT(PPC_RAW_MTCTR(bpf_to_ppc(TMP_REG_1))); > > /* tear down stack, restore NVRs, ... */ > @@ -365,6 +427,7 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct code > u32 *addrs, int pass, bool extra_pass) > { > enum stf_barrier_type stf_barrier = stf_barrier_type_get(); > + bool has_kfunc_call = bpf_prog_has_kfunc_call(fp); > const struct bpf_insn *insn = fp->insnsi; > int flen = fp->len; > int i, ret; > @@ -993,9 +1056,11 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct code > return ret; > > if (func_addr_fixed) > - ret = bpf_jit_emit_func_call_hlp(image, ctx, func_addr); > + ret = bpf_jit_emit_func_call_hlp(image, ctx, func_addr, > + has_kfunc_call); Doesn't this fit on a single line ? > 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, > + has_kfunc_call); Same. Nowadays lines up to 100 chars are the norm. > > if (ret) > return ret; > @@ -1204,7 +1269,7 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct code > */ > case BPF_JMP | BPF_TAIL_CALL: > ctx->seen |= SEEN_TAILCALL; > - ret = bpf_jit_emit_tail_call(image, ctx, addrs[i + 1]); > + ret = bpf_jit_emit_tail_call(image, ctx, addrs[i + 1], has_kfunc_call); > if (ret < 0) > return ret; > break;
On Thu, Feb 01, 2024 at 10:42:48PM +0530, Hari Bathini wrote: > Currently, bpf jit code on powerpc assumes all the bpf functions and > helpers to be kernel text. This is false for kfunc case, as function > addresses are mostly module addresses in that case. Ensure module > addresses are supported to enable kfunc support. I don't think that statement is entirely accurate. Our current assumptions are still correct in the sense that: 1. all BPF helpers are part of core kernel text, calls to which are generated in bpf_jit_emit_func_call_hlp(). 2. bpf-to-bpf calls go out to module area where the JIT output of BPF subprogs are written to, handled by bpf_jit_emit_func_call_rel(). kfunc calls add another variant where BPF progs can call directly into a kernel function (similar to a BPF helper call), except for the fact that the said function could be in a kernel module. > > Assume kernel text address for programs with no kfunc call to optimize > instruction sequence in that case. Add a check to error out if this > assumption ever changes in the future. > > Signed-off-by: Hari Bathini <hbathini@linux.ibm.com> > --- > > Changes in v2: > * Using bpf_prog_has_kfunc_call() to decide whether to use optimized > instruction sequence or not as suggested by Naveen. > > > arch/powerpc/net/bpf_jit.h | 5 +- > arch/powerpc/net/bpf_jit_comp.c | 4 +- > arch/powerpc/net/bpf_jit_comp32.c | 8 ++- > arch/powerpc/net/bpf_jit_comp64.c | 109 ++++++++++++++++++++++++------ > 4 files changed, 97 insertions(+), 29 deletions(-) > > diff --git a/arch/powerpc/net/bpf_jit.h b/arch/powerpc/net/bpf_jit.h > index cdea5dccaefe..fc56ee0ee9c5 100644 > --- a/arch/powerpc/net/bpf_jit.h > +++ b/arch/powerpc/net/bpf_jit.h > @@ -160,10 +160,11 @@ static inline void bpf_clear_seen_register(struct codegen_context *ctx, int i) > } > > void bpf_jit_init_reg_mapping(struct codegen_context *ctx); > -int bpf_jit_emit_func_call_rel(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, > + bool has_kfunc_call); > int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct codegen_context *ctx, > u32 *addrs, int pass, bool extra_pass); > -void bpf_jit_build_prologue(u32 *image, struct codegen_context *ctx); > +void bpf_jit_build_prologue(u32 *image, struct codegen_context *ctx, bool has_kfunc_call); > void bpf_jit_build_epilogue(u32 *image, struct codegen_context *ctx); > void bpf_jit_realloc_regs(struct codegen_context *ctx); > int bpf_jit_emit_exit_insn(u32 *image, struct codegen_context *ctx, int tmp_reg, long exit_addr); > diff --git a/arch/powerpc/net/bpf_jit_comp.c b/arch/powerpc/net/bpf_jit_comp.c > index 0f9a21783329..7b4103b4c929 100644 > --- a/arch/powerpc/net/bpf_jit_comp.c > +++ b/arch/powerpc/net/bpf_jit_comp.c > @@ -163,7 +163,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp) > * update ctgtx.idx as it pretends to output instructions, then we can > * calculate total size from idx. > */ > - bpf_jit_build_prologue(NULL, &cgctx); > + bpf_jit_build_prologue(NULL, &cgctx, bpf_prog_has_kfunc_call(fp)); > addrs[fp->len] = cgctx.idx * 4; > bpf_jit_build_epilogue(NULL, &cgctx); > > @@ -192,7 +192,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp) > /* Now build the prologue, body code & epilogue for real. */ > cgctx.idx = 0; > cgctx.alt_exit_addr = 0; > - bpf_jit_build_prologue(code_base, &cgctx); > + bpf_jit_build_prologue(code_base, &cgctx, bpf_prog_has_kfunc_call(fp)); > if (bpf_jit_build_body(fp, code_base, fcode_base, &cgctx, addrs, pass, > extra_pass)) { > bpf_arch_text_copy(&fhdr->size, &hdr->size, sizeof(hdr->size)); > diff --git a/arch/powerpc/net/bpf_jit_comp32.c b/arch/powerpc/net/bpf_jit_comp32.c > index 2f39c50ca729..447747e51a58 100644 > --- a/arch/powerpc/net/bpf_jit_comp32.c > +++ b/arch/powerpc/net/bpf_jit_comp32.c > @@ -123,7 +123,7 @@ void bpf_jit_realloc_regs(struct codegen_context *ctx) > } > } > > -void bpf_jit_build_prologue(u32 *image, struct codegen_context *ctx) > +void bpf_jit_build_prologue(u32 *image, struct codegen_context *ctx, bool has_kfunc_call) > { > int i; > > @@ -201,7 +201,8 @@ void bpf_jit_build_epilogue(u32 *image, struct codegen_context *ctx) > } > > /* Relative offset needs to be calculated based on final image location */ > -int bpf_jit_emit_func_call_rel(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, > + bool has_kfunc_call) > { > s32 rel = (s32)func - (s32)(fimage + ctx->idx); > > @@ -1054,7 +1055,8 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct code > EMIT(PPC_RAW_STW(bpf_to_ppc(BPF_REG_5), _R1, 12)); > } > > - ret = bpf_jit_emit_func_call_rel(image, fimage, ctx, func_addr); > + ret = bpf_jit_emit_func_call_rel(image, fimage, ctx, func_addr, > + bpf_prog_has_kfunc_call(fp)); > if (ret) > return ret; > > diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c > index 79f23974a320..385a5df1670c 100644 > --- a/arch/powerpc/net/bpf_jit_comp64.c > +++ b/arch/powerpc/net/bpf_jit_comp64.c > @@ -122,12 +122,17 @@ void bpf_jit_realloc_regs(struct codegen_context *ctx) > { > } > > -void bpf_jit_build_prologue(u32 *image, struct codegen_context *ctx) > +void bpf_jit_build_prologue(u32 *image, struct codegen_context *ctx, bool has_kfunc_call) > { > int i; > > #ifndef CONFIG_PPC_KERNEL_PCREL > - if (IS_ENABLED(CONFIG_PPC64_ELF_ABI_V2)) > + /* > + * If the program doesn't have a kfunc call, all BPF helpers are part of kernel text > + * and all BPF programs/functions utilize the kernel TOC. So, optimize the > + * instruction sequence by using kernel toc in r2 for that case. > + */ > + if (!has_kfunc_call && IS_ENABLED(CONFIG_PPC64_ELF_ABI_V2)) > EMIT(PPC_RAW_LD(_R2, _R13, offsetof(struct paca_struct, kernel_toc))); I don't think this is the correct approach. As far as I can see, we can still retain the current function calling sequence utilizing TOC even when a kfunc call is present. More on that below... > #endif > > @@ -202,12 +207,17 @@ 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, struct codegen_context *ctx, u64 func) > +static int bpf_jit_emit_func_call_hlp(u32 *image, struct codegen_context *ctx, u64 func, > + bool has_kfunc_call) > { > unsigned long func_addr = func ? ppc_function_entry((void *)func) : 0; > long reladdr; > > - if (WARN_ON_ONCE(!core_kernel_text(func_addr))) > + /* > + * If the program doesn't have a kfunc call, all BPF helpers are assumed to be part of > + * kernel text. Don't proceed if that assumption ever changes in future. > + */ > + if (!has_kfunc_call && WARN_ON_ONCE(!core_kernel_text(func_addr))) > return -EINVAL; Rather than pass around the presence of a kfunc call in a particular BPF prog, I think we should be able to update bpf_jit_emit_func_call_hlp() to handle module addresses. That way, existing calling sequence can continue to be used for BPF helpers and other BPF functions. bpf_jit_get_func_addr() should return the correct function address for a kfunc call. So, all we need here is to check if that address belongs to a module and use a different instruction sequence for that: - for pcrel and elf abiv2, we can simply load the full address using PPC_LI64() and use that, rather than utilizing the TOC. Note that we will need to use the GEP here so the target function can setup its own TOC. For elf abiv2, we will need an additional instruction after the bctrl() to load the kernel toc from paca. - for elf abiv1, we will need to load the function address and toc value from the function descriptor, followed by restoring kernel toc like above. For kfunc calls to core kernel functions, we should be able to retain existing sequence using TOC. > > if (IS_ENABLED(CONFIG_PPC_KERNEL_PCREL)) { > @@ -225,30 +235,55 @@ static int bpf_jit_emit_func_call_hlp(u32 *image, struct codegen_context *ctx, u > EMIT(PPC_RAW_BCTR()); > > } else { > - reladdr = func_addr - kernel_toc_addr(); > - if (reladdr > 0x7FFFFFFF || reladdr < -(0x80000000L)) { > - pr_err("eBPF: address of %ps out of range of kernel_toc.\n", (void *)func); > - return -ERANGE; > - } > + if (has_kfunc_call) { > +#ifdef PPC64_ELF_ABI_v1 > + /* func points to the function descriptor */ > + PPC_LI64(b2p[TMP_REG_2], func); > + /* Load actual entry point from function descriptor */ > + PPC_BPF_LL(b2p[TMP_REG_1], b2p[TMP_REG_2], 0); > + /* ... and move it to CTR */ > + EMIT(PPC_RAW_MTCTR(b2p[TMP_REG_1])); > + /* > + * Load TOC from function descriptor at offset 8. > + * We can clobber r2 since we get called through a > + * function pointer (so caller will save/restore r2) > + * and since we don't use a TOC ourself. > + */ > + PPC_BPF_LL(2, b2p[TMP_REG_2], 8); > +#else > + /* We can clobber r12 */ > + PPC_LI64(12, func); > + EMIT(PPC_RAW_MTCTR(12)); > +#endif > + } else { > + reladdr = func_addr - kernel_toc_addr(); > + if (reladdr > 0x7FFFFFFF || reladdr < -(0x80000000L)) { > + pr_err("eBPF: address of %ps out of range of kernel_toc.\n", > + (void *)func); > + return -ERANGE; > + } > > - EMIT(PPC_RAW_ADDIS(_R12, _R2, PPC_HA(reladdr))); > - EMIT(PPC_RAW_ADDI(_R12, _R12, PPC_LO(reladdr))); > - EMIT(PPC_RAW_MTCTR(_R12)); > + EMIT(PPC_RAW_ADDIS(_R12, _R2, PPC_HA(reladdr))); > + EMIT(PPC_RAW_ADDI(_R12, _R12, PPC_LO(reladdr))); > + EMIT(PPC_RAW_MTCTR(_R12)); > + } > EMIT(PPC_RAW_BCTRL()); > } > > return 0; > } > > -int bpf_jit_emit_func_call_rel(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, > + bool has_kfunc_call) > { This function shouldn't need any changes since this is only for calling other bpf progs. - Naveen
On 13/02/24 1:23 pm, Christophe Leroy wrote: > > > Le 01/02/2024 à 18:12, Hari Bathini a écrit : >> Currently, bpf jit code on powerpc assumes all the bpf functions and >> helpers to be kernel text. This is false for kfunc case, as function >> addresses are mostly module addresses in that case. Ensure module >> addresses are supported to enable kfunc support. >> >> Assume kernel text address for programs with no kfunc call to optimize >> instruction sequence in that case. Add a check to error out if this >> assumption ever changes in the future. >> >> Signed-off-by: Hari Bathini <hbathini@linux.ibm.com> >> --- >> >> Changes in v2: >> * Using bpf_prog_has_kfunc_call() to decide whether to use optimized >> instruction sequence or not as suggested by Naveen. >> >> >> arch/powerpc/net/bpf_jit.h | 5 +- >> arch/powerpc/net/bpf_jit_comp.c | 4 +- >> arch/powerpc/net/bpf_jit_comp32.c | 8 ++- >> arch/powerpc/net/bpf_jit_comp64.c | 109 ++++++++++++++++++++++++------ >> 4 files changed, 97 insertions(+), 29 deletions(-) >> >> diff --git a/arch/powerpc/net/bpf_jit.h b/arch/powerpc/net/bpf_jit.h >> index cdea5dccaefe..fc56ee0ee9c5 100644 >> --- a/arch/powerpc/net/bpf_jit.h >> +++ b/arch/powerpc/net/bpf_jit.h >> @@ -160,10 +160,11 @@ static inline void bpf_clear_seen_register(struct codegen_context *ctx, int i) >> } >> >> void bpf_jit_init_reg_mapping(struct codegen_context *ctx); >> -int bpf_jit_emit_func_call_rel(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, >> + bool has_kfunc_call); >> int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct codegen_context *ctx, >> u32 *addrs, int pass, bool extra_pass); >> -void bpf_jit_build_prologue(u32 *image, struct codegen_context *ctx); >> +void bpf_jit_build_prologue(u32 *image, struct codegen_context *ctx, bool has_kfunc_call); >> void bpf_jit_build_epilogue(u32 *image, struct codegen_context *ctx); >> void bpf_jit_realloc_regs(struct codegen_context *ctx); >> int bpf_jit_emit_exit_insn(u32 *image, struct codegen_context *ctx, int tmp_reg, long exit_addr); >> diff --git a/arch/powerpc/net/bpf_jit_comp.c b/arch/powerpc/net/bpf_jit_comp.c >> index 0f9a21783329..7b4103b4c929 100644 >> --- a/arch/powerpc/net/bpf_jit_comp.c >> +++ b/arch/powerpc/net/bpf_jit_comp.c >> @@ -163,7 +163,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp) >> * update ctgtx.idx as it pretends to output instructions, then we can >> * calculate total size from idx. >> */ >> - bpf_jit_build_prologue(NULL, &cgctx); >> + bpf_jit_build_prologue(NULL, &cgctx, bpf_prog_has_kfunc_call(fp)); >> addrs[fp->len] = cgctx.idx * 4; >> bpf_jit_build_epilogue(NULL, &cgctx); >> >> @@ -192,7 +192,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp) >> /* Now build the prologue, body code & epilogue for real. */ >> cgctx.idx = 0; >> cgctx.alt_exit_addr = 0; >> - bpf_jit_build_prologue(code_base, &cgctx); >> + bpf_jit_build_prologue(code_base, &cgctx, bpf_prog_has_kfunc_call(fp)); >> if (bpf_jit_build_body(fp, code_base, fcode_base, &cgctx, addrs, pass, >> extra_pass)) { >> bpf_arch_text_copy(&fhdr->size, &hdr->size, sizeof(hdr->size)); >> diff --git a/arch/powerpc/net/bpf_jit_comp32.c b/arch/powerpc/net/bpf_jit_comp32.c >> index 2f39c50ca729..447747e51a58 100644 >> --- a/arch/powerpc/net/bpf_jit_comp32.c >> +++ b/arch/powerpc/net/bpf_jit_comp32.c >> @@ -123,7 +123,7 @@ void bpf_jit_realloc_regs(struct codegen_context *ctx) >> } >> } >> >> -void bpf_jit_build_prologue(u32 *image, struct codegen_context *ctx) >> +void bpf_jit_build_prologue(u32 *image, struct codegen_context *ctx, bool has_kfunc_call) >> { >> int i; >> >> @@ -201,7 +201,8 @@ void bpf_jit_build_epilogue(u32 *image, struct codegen_context *ctx) >> } >> >> /* Relative offset needs to be calculated based on final image location */ >> -int bpf_jit_emit_func_call_rel(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, >> + bool has_kfunc_call) >> { >> s32 rel = (s32)func - (s32)(fimage + ctx->idx); >> >> @@ -1054,7 +1055,8 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct code >> EMIT(PPC_RAW_STW(bpf_to_ppc(BPF_REG_5), _R1, 12)); >> } >> >> - ret = bpf_jit_emit_func_call_rel(image, fimage, ctx, func_addr); >> + ret = bpf_jit_emit_func_call_rel(image, fimage, ctx, func_addr, >> + bpf_prog_has_kfunc_call(fp)); >> if (ret) >> return ret; >> >> diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c >> index 79f23974a320..385a5df1670c 100644 >> --- a/arch/powerpc/net/bpf_jit_comp64.c >> +++ b/arch/powerpc/net/bpf_jit_comp64.c >> @@ -122,12 +122,17 @@ void bpf_jit_realloc_regs(struct codegen_context *ctx) >> { >> } >> >> -void bpf_jit_build_prologue(u32 *image, struct codegen_context *ctx) >> +void bpf_jit_build_prologue(u32 *image, struct codegen_context *ctx, bool has_kfunc_call) >> { >> int i; >> >> #ifndef CONFIG_PPC_KERNEL_PCREL >> - if (IS_ENABLED(CONFIG_PPC64_ELF_ABI_V2)) >> + /* >> + * If the program doesn't have a kfunc call, all BPF helpers are part of kernel text >> + * and all BPF programs/functions utilize the kernel TOC. So, optimize the >> + * instruction sequence by using kernel toc in r2 for that case. >> + */ >> + if (!has_kfunc_call && IS_ENABLED(CONFIG_PPC64_ELF_ABI_V2)) >> EMIT(PPC_RAW_LD(_R2, _R13, offsetof(struct paca_struct, kernel_toc))); >> #endif >> >> @@ -202,12 +207,17 @@ 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, struct codegen_context *ctx, u64 func) >> +static int bpf_jit_emit_func_call_hlp(u32 *image, struct codegen_context *ctx, u64 func, >> + bool has_kfunc_call) >> { >> unsigned long func_addr = func ? ppc_function_entry((void *)func) : 0; >> long reladdr; >> >> - if (WARN_ON_ONCE(!core_kernel_text(func_addr))) >> + /* >> + * If the program doesn't have a kfunc call, all BPF helpers are assumed to be part of >> + * kernel text. Don't proceed if that assumption ever changes in future. >> + */ >> + if (!has_kfunc_call && WARN_ON_ONCE(!core_kernel_text(func_addr))) >> return -EINVAL; >> >> if (IS_ENABLED(CONFIG_PPC_KERNEL_PCREL)) { >> @@ -225,30 +235,55 @@ static int bpf_jit_emit_func_call_hlp(u32 *image, struct codegen_context *ctx, u >> EMIT(PPC_RAW_BCTR()); >> >> } else { >> - reladdr = func_addr - kernel_toc_addr(); >> - if (reladdr > 0x7FFFFFFF || reladdr < -(0x80000000L)) { >> - pr_err("eBPF: address of %ps out of range of kernel_toc.\n", (void *)func); >> - return -ERANGE; >> - } >> + if (has_kfunc_call) { >> +#ifdef PPC64_ELF_ABI_v1 > > I can't see a reason for a #ifdef here, why not use IS_ENABLED() like > other places ? > >> + /* func points to the function descriptor */ >> + PPC_LI64(b2p[TMP_REG_2], func); >> + /* Load actual entry point from function descriptor */ >> + PPC_BPF_LL(b2p[TMP_REG_1], b2p[TMP_REG_2], 0); >> + /* ... and move it to CTR */ >> + EMIT(PPC_RAW_MTCTR(b2p[TMP_REG_1])); >> + /* >> + * Load TOC from function descriptor at offset 8. >> + * We can clobber r2 since we get called through a >> + * function pointer (so caller will save/restore r2) >> + * and since we don't use a TOC ourself. >> + */ >> + PPC_BPF_LL(2, b2p[TMP_REG_2], 8); >> +#else >> + /* We can clobber r12 */ >> + PPC_LI64(12, func); >> + EMIT(PPC_RAW_MTCTR(12)); >> +#endif >> + } else { >> + reladdr = func_addr - kernel_toc_addr(); >> + if (reladdr > 0x7FFFFFFF || reladdr < -(0x80000000L)) { >> + pr_err("eBPF: address of %ps out of range of kernel_toc.\n", >> + (void *)func); >> + return -ERANGE; >> + } >> >> - EMIT(PPC_RAW_ADDIS(_R12, _R2, PPC_HA(reladdr))); >> - EMIT(PPC_RAW_ADDI(_R12, _R12, PPC_LO(reladdr))); >> - EMIT(PPC_RAW_MTCTR(_R12)); >> + EMIT(PPC_RAW_ADDIS(_R12, _R2, PPC_HA(reladdr))); >> + EMIT(PPC_RAW_ADDI(_R12, _R12, PPC_LO(reladdr))); >> + EMIT(PPC_RAW_MTCTR(_R12)); >> + } >> EMIT(PPC_RAW_BCTRL()); >> } >> >> return 0; >> } >> >> -int bpf_jit_emit_func_call_rel(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, >> + bool has_kfunc_call) >> { >> unsigned int i, ctx_idx = ctx->idx; >> >> - if (WARN_ON_ONCE(func && is_module_text_address(func))) >> + if (WARN_ON_ONCE(func && !has_kfunc_call && is_module_text_address(func))) >> return -EINVAL; >> >> /* skip past descriptor if elf v1 */ >> - func += FUNCTION_DESCR_SIZE; >> + if (!has_kfunc_call) >> + func += FUNCTION_DESCR_SIZE; >> >> /* Load function address into r12 */ >> PPC_LI64(_R12, func); >> @@ -267,13 +302,28 @@ int bpf_jit_emit_func_call_rel(u32 *image, u32 *fimage, struct codegen_context * >> for (i = ctx->idx - ctx_idx; i < 5; i++) >> EMIT(PPC_RAW_NOP()); >> >> +#ifdef PPC64_ELF_ABI_v1 > > I can't see a reason for a #ifdef here, why not use IS_ENABLED() like > other places ? Will update. > > >> + if (has_kfunc_call) { >> + /* >> + * Load TOC from function descriptor at offset 8. >> + * We can clobber r2 since we get called through a >> + * function pointer (so caller will save/restore r2) >> + * and since we don't use a TOC ourself. >> + */ >> + PPC_BPF_LL(2, 12, 8); >> + /* Load actual entry point from function descriptor */ >> + PPC_BPF_LL(12, 12, 0); >> + } >> +#endif >> + >> 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) >> +static int bpf_jit_emit_tail_call(u32 *image, struct codegen_context *ctx, u32 out, >> + bool has_kfunc_call) >> { >> /* >> * By now, the eBPF program has already setup parameters in r3, r4 and r5 >> @@ -285,7 +335,7 @@ static int bpf_jit_emit_tail_call(u32 *image, struct codegen_context *ctx, u32 o >> int b2p_index = bpf_to_ppc(BPF_REG_3); >> int bpf_tailcall_prologue_size = 8; >> >> - if (IS_ENABLED(CONFIG_PPC64_ELF_ABI_V2)) >> + if (!has_kfunc_call && IS_ENABLED(CONFIG_PPC64_ELF_ABI_V2)) >> bpf_tailcall_prologue_size += 4; /* skip past the toc load */ >> >> /* >> @@ -325,8 +375,20 @@ static int bpf_jit_emit_tail_call(u32 *image, struct codegen_context *ctx, u32 o >> >> /* goto *(prog->bpf_func + prologue_size); */ >> EMIT(PPC_RAW_LD(bpf_to_ppc(TMP_REG_1), bpf_to_ppc(TMP_REG_1), offsetof(struct bpf_prog, bpf_func))); >> - EMIT(PPC_RAW_ADDI(bpf_to_ppc(TMP_REG_1), bpf_to_ppc(TMP_REG_1), >> - FUNCTION_DESCR_SIZE + bpf_tailcall_prologue_size)); >> + if (has_kfunc_call) { >> +#ifdef PPC64_ELF_ABI_v1 > > I can't see a reason for a #ifdef here, why not use IS_ENABLED() like > other places ? > >> + /* skip past the function descriptor */ >> + EMIT(PPC_RAW_ADDI(bpf_to_ppc(TMP_REG_1), bpf_to_ppc(TMP_REG_1), >> + FUNCTION_DESCR_SIZE + bpf_tailcall_prologue_size)); >> +#else >> + EMIT(PPC_RAW_ADDI(bpf_to_ppc(TMP_REG_1), bpf_to_ppc(TMP_REG_1), >> + bpf_tailcall_prologue_size)); >> +#endif >> + } else { >> + EMIT(PPC_RAW_ADDI(bpf_to_ppc(TMP_REG_1), bpf_to_ppc(TMP_REG_1), >> + FUNCTION_DESCR_SIZE + bpf_tailcall_prologue_size)); >> + } >> + >> EMIT(PPC_RAW_MTCTR(bpf_to_ppc(TMP_REG_1))); >> >> /* tear down stack, restore NVRs, ... */ >> @@ -365,6 +427,7 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct code >> u32 *addrs, int pass, bool extra_pass) >> { >> enum stf_barrier_type stf_barrier = stf_barrier_type_get(); >> + bool has_kfunc_call = bpf_prog_has_kfunc_call(fp); >> const struct bpf_insn *insn = fp->insnsi; >> int flen = fp->len; >> int i, ret; >> @@ -993,9 +1056,11 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct code >> return ret; >> >> if (func_addr_fixed) >> - ret = bpf_jit_emit_func_call_hlp(image, ctx, func_addr); >> + ret = bpf_jit_emit_func_call_hlp(image, ctx, func_addr, >> + has_kfunc_call); > > Doesn't this fit on a single line ? > >> 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, >> + has_kfunc_call); > > Same. Nowadays lines up to 100 chars are the norm. Goes beyond 100 chars. > >> >> if (ret) >> return ret; >> @@ -1204,7 +1269,7 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct code >> */ >> case BPF_JMP | BPF_TAIL_CALL: >> ctx->seen |= SEEN_TAILCALL; >> - ret = bpf_jit_emit_tail_call(image, ctx, addrs[i + 1]); >> + ret = bpf_jit_emit_tail_call(image, ctx, addrs[i + 1], has_kfunc_call); >> if (ret < 0) >> return ret; >> break; Thanks Hari
diff --git a/arch/powerpc/net/bpf_jit.h b/arch/powerpc/net/bpf_jit.h index cdea5dccaefe..fc56ee0ee9c5 100644 --- a/arch/powerpc/net/bpf_jit.h +++ b/arch/powerpc/net/bpf_jit.h @@ -160,10 +160,11 @@ static inline void bpf_clear_seen_register(struct codegen_context *ctx, int i) } void bpf_jit_init_reg_mapping(struct codegen_context *ctx); -int bpf_jit_emit_func_call_rel(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, + bool has_kfunc_call); int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct codegen_context *ctx, u32 *addrs, int pass, bool extra_pass); -void bpf_jit_build_prologue(u32 *image, struct codegen_context *ctx); +void bpf_jit_build_prologue(u32 *image, struct codegen_context *ctx, bool has_kfunc_call); void bpf_jit_build_epilogue(u32 *image, struct codegen_context *ctx); void bpf_jit_realloc_regs(struct codegen_context *ctx); int bpf_jit_emit_exit_insn(u32 *image, struct codegen_context *ctx, int tmp_reg, long exit_addr); diff --git a/arch/powerpc/net/bpf_jit_comp.c b/arch/powerpc/net/bpf_jit_comp.c index 0f9a21783329..7b4103b4c929 100644 --- a/arch/powerpc/net/bpf_jit_comp.c +++ b/arch/powerpc/net/bpf_jit_comp.c @@ -163,7 +163,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp) * update ctgtx.idx as it pretends to output instructions, then we can * calculate total size from idx. */ - bpf_jit_build_prologue(NULL, &cgctx); + bpf_jit_build_prologue(NULL, &cgctx, bpf_prog_has_kfunc_call(fp)); addrs[fp->len] = cgctx.idx * 4; bpf_jit_build_epilogue(NULL, &cgctx); @@ -192,7 +192,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp) /* Now build the prologue, body code & epilogue for real. */ cgctx.idx = 0; cgctx.alt_exit_addr = 0; - bpf_jit_build_prologue(code_base, &cgctx); + bpf_jit_build_prologue(code_base, &cgctx, bpf_prog_has_kfunc_call(fp)); if (bpf_jit_build_body(fp, code_base, fcode_base, &cgctx, addrs, pass, extra_pass)) { bpf_arch_text_copy(&fhdr->size, &hdr->size, sizeof(hdr->size)); diff --git a/arch/powerpc/net/bpf_jit_comp32.c b/arch/powerpc/net/bpf_jit_comp32.c index 2f39c50ca729..447747e51a58 100644 --- a/arch/powerpc/net/bpf_jit_comp32.c +++ b/arch/powerpc/net/bpf_jit_comp32.c @@ -123,7 +123,7 @@ void bpf_jit_realloc_regs(struct codegen_context *ctx) } } -void bpf_jit_build_prologue(u32 *image, struct codegen_context *ctx) +void bpf_jit_build_prologue(u32 *image, struct codegen_context *ctx, bool has_kfunc_call) { int i; @@ -201,7 +201,8 @@ void bpf_jit_build_epilogue(u32 *image, struct codegen_context *ctx) } /* Relative offset needs to be calculated based on final image location */ -int bpf_jit_emit_func_call_rel(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, + bool has_kfunc_call) { s32 rel = (s32)func - (s32)(fimage + ctx->idx); @@ -1054,7 +1055,8 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct code EMIT(PPC_RAW_STW(bpf_to_ppc(BPF_REG_5), _R1, 12)); } - ret = bpf_jit_emit_func_call_rel(image, fimage, ctx, func_addr); + ret = bpf_jit_emit_func_call_rel(image, fimage, ctx, func_addr, + bpf_prog_has_kfunc_call(fp)); if (ret) return ret; diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c index 79f23974a320..385a5df1670c 100644 --- a/arch/powerpc/net/bpf_jit_comp64.c +++ b/arch/powerpc/net/bpf_jit_comp64.c @@ -122,12 +122,17 @@ void bpf_jit_realloc_regs(struct codegen_context *ctx) { } -void bpf_jit_build_prologue(u32 *image, struct codegen_context *ctx) +void bpf_jit_build_prologue(u32 *image, struct codegen_context *ctx, bool has_kfunc_call) { int i; #ifndef CONFIG_PPC_KERNEL_PCREL - if (IS_ENABLED(CONFIG_PPC64_ELF_ABI_V2)) + /* + * If the program doesn't have a kfunc call, all BPF helpers are part of kernel text + * and all BPF programs/functions utilize the kernel TOC. So, optimize the + * instruction sequence by using kernel toc in r2 for that case. + */ + if (!has_kfunc_call && IS_ENABLED(CONFIG_PPC64_ELF_ABI_V2)) EMIT(PPC_RAW_LD(_R2, _R13, offsetof(struct paca_struct, kernel_toc))); #endif @@ -202,12 +207,17 @@ 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, struct codegen_context *ctx, u64 func) +static int bpf_jit_emit_func_call_hlp(u32 *image, struct codegen_context *ctx, u64 func, + bool has_kfunc_call) { unsigned long func_addr = func ? ppc_function_entry((void *)func) : 0; long reladdr; - if (WARN_ON_ONCE(!core_kernel_text(func_addr))) + /* + * If the program doesn't have a kfunc call, all BPF helpers are assumed to be part of + * kernel text. Don't proceed if that assumption ever changes in future. + */ + if (!has_kfunc_call && WARN_ON_ONCE(!core_kernel_text(func_addr))) return -EINVAL; if (IS_ENABLED(CONFIG_PPC_KERNEL_PCREL)) { @@ -225,30 +235,55 @@ static int bpf_jit_emit_func_call_hlp(u32 *image, struct codegen_context *ctx, u EMIT(PPC_RAW_BCTR()); } else { - reladdr = func_addr - kernel_toc_addr(); - if (reladdr > 0x7FFFFFFF || reladdr < -(0x80000000L)) { - pr_err("eBPF: address of %ps out of range of kernel_toc.\n", (void *)func); - return -ERANGE; - } + if (has_kfunc_call) { +#ifdef PPC64_ELF_ABI_v1 + /* func points to the function descriptor */ + PPC_LI64(b2p[TMP_REG_2], func); + /* Load actual entry point from function descriptor */ + PPC_BPF_LL(b2p[TMP_REG_1], b2p[TMP_REG_2], 0); + /* ... and move it to CTR */ + EMIT(PPC_RAW_MTCTR(b2p[TMP_REG_1])); + /* + * Load TOC from function descriptor at offset 8. + * We can clobber r2 since we get called through a + * function pointer (so caller will save/restore r2) + * and since we don't use a TOC ourself. + */ + PPC_BPF_LL(2, b2p[TMP_REG_2], 8); +#else + /* We can clobber r12 */ + PPC_LI64(12, func); + EMIT(PPC_RAW_MTCTR(12)); +#endif + } else { + reladdr = func_addr - kernel_toc_addr(); + if (reladdr > 0x7FFFFFFF || reladdr < -(0x80000000L)) { + pr_err("eBPF: address of %ps out of range of kernel_toc.\n", + (void *)func); + return -ERANGE; + } - EMIT(PPC_RAW_ADDIS(_R12, _R2, PPC_HA(reladdr))); - EMIT(PPC_RAW_ADDI(_R12, _R12, PPC_LO(reladdr))); - EMIT(PPC_RAW_MTCTR(_R12)); + EMIT(PPC_RAW_ADDIS(_R12, _R2, PPC_HA(reladdr))); + EMIT(PPC_RAW_ADDI(_R12, _R12, PPC_LO(reladdr))); + EMIT(PPC_RAW_MTCTR(_R12)); + } EMIT(PPC_RAW_BCTRL()); } return 0; } -int bpf_jit_emit_func_call_rel(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, + bool has_kfunc_call) { unsigned int i, ctx_idx = ctx->idx; - if (WARN_ON_ONCE(func && is_module_text_address(func))) + if (WARN_ON_ONCE(func && !has_kfunc_call && is_module_text_address(func))) return -EINVAL; /* skip past descriptor if elf v1 */ - func += FUNCTION_DESCR_SIZE; + if (!has_kfunc_call) + func += FUNCTION_DESCR_SIZE; /* Load function address into r12 */ PPC_LI64(_R12, func); @@ -267,13 +302,28 @@ int bpf_jit_emit_func_call_rel(u32 *image, u32 *fimage, struct codegen_context * for (i = ctx->idx - ctx_idx; i < 5; i++) EMIT(PPC_RAW_NOP()); +#ifdef PPC64_ELF_ABI_v1 + if (has_kfunc_call) { + /* + * Load TOC from function descriptor at offset 8. + * We can clobber r2 since we get called through a + * function pointer (so caller will save/restore r2) + * and since we don't use a TOC ourself. + */ + PPC_BPF_LL(2, 12, 8); + /* Load actual entry point from function descriptor */ + PPC_BPF_LL(12, 12, 0); + } +#endif + 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) +static int bpf_jit_emit_tail_call(u32 *image, struct codegen_context *ctx, u32 out, + bool has_kfunc_call) { /* * By now, the eBPF program has already setup parameters in r3, r4 and r5 @@ -285,7 +335,7 @@ static int bpf_jit_emit_tail_call(u32 *image, struct codegen_context *ctx, u32 o int b2p_index = bpf_to_ppc(BPF_REG_3); int bpf_tailcall_prologue_size = 8; - if (IS_ENABLED(CONFIG_PPC64_ELF_ABI_V2)) + if (!has_kfunc_call && IS_ENABLED(CONFIG_PPC64_ELF_ABI_V2)) bpf_tailcall_prologue_size += 4; /* skip past the toc load */ /* @@ -325,8 +375,20 @@ static int bpf_jit_emit_tail_call(u32 *image, struct codegen_context *ctx, u32 o /* goto *(prog->bpf_func + prologue_size); */ EMIT(PPC_RAW_LD(bpf_to_ppc(TMP_REG_1), bpf_to_ppc(TMP_REG_1), offsetof(struct bpf_prog, bpf_func))); - EMIT(PPC_RAW_ADDI(bpf_to_ppc(TMP_REG_1), bpf_to_ppc(TMP_REG_1), - FUNCTION_DESCR_SIZE + bpf_tailcall_prologue_size)); + if (has_kfunc_call) { +#ifdef PPC64_ELF_ABI_v1 + /* skip past the function descriptor */ + EMIT(PPC_RAW_ADDI(bpf_to_ppc(TMP_REG_1), bpf_to_ppc(TMP_REG_1), + FUNCTION_DESCR_SIZE + bpf_tailcall_prologue_size)); +#else + EMIT(PPC_RAW_ADDI(bpf_to_ppc(TMP_REG_1), bpf_to_ppc(TMP_REG_1), + bpf_tailcall_prologue_size)); +#endif + } else { + EMIT(PPC_RAW_ADDI(bpf_to_ppc(TMP_REG_1), bpf_to_ppc(TMP_REG_1), + FUNCTION_DESCR_SIZE + bpf_tailcall_prologue_size)); + } + EMIT(PPC_RAW_MTCTR(bpf_to_ppc(TMP_REG_1))); /* tear down stack, restore NVRs, ... */ @@ -365,6 +427,7 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct code u32 *addrs, int pass, bool extra_pass) { enum stf_barrier_type stf_barrier = stf_barrier_type_get(); + bool has_kfunc_call = bpf_prog_has_kfunc_call(fp); const struct bpf_insn *insn = fp->insnsi; int flen = fp->len; int i, ret; @@ -993,9 +1056,11 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct code return ret; if (func_addr_fixed) - ret = bpf_jit_emit_func_call_hlp(image, ctx, func_addr); + ret = bpf_jit_emit_func_call_hlp(image, ctx, func_addr, + has_kfunc_call); 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, + has_kfunc_call); if (ret) return ret; @@ -1204,7 +1269,7 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct code */ case BPF_JMP | BPF_TAIL_CALL: ctx->seen |= SEEN_TAILCALL; - ret = bpf_jit_emit_tail_call(image, ctx, addrs[i + 1]); + ret = bpf_jit_emit_tail_call(image, ctx, addrs[i + 1], has_kfunc_call); if (ret < 0) return ret; break;
Currently, bpf jit code on powerpc assumes all the bpf functions and helpers to be kernel text. This is false for kfunc case, as function addresses are mostly module addresses in that case. Ensure module addresses are supported to enable kfunc support. Assume kernel text address for programs with no kfunc call to optimize instruction sequence in that case. Add a check to error out if this assumption ever changes in the future. Signed-off-by: Hari Bathini <hbathini@linux.ibm.com> --- Changes in v2: * Using bpf_prog_has_kfunc_call() to decide whether to use optimized instruction sequence or not as suggested by Naveen. arch/powerpc/net/bpf_jit.h | 5 +- arch/powerpc/net/bpf_jit_comp.c | 4 +- arch/powerpc/net/bpf_jit_comp32.c | 8 ++- arch/powerpc/net/bpf_jit_comp64.c | 109 ++++++++++++++++++++++++------ 4 files changed, 97 insertions(+), 29 deletions(-)