From: Abhishek Dubey <[email protected]> Implement JIT support for fsession in powerpc64 trampoline. The trampoline stack now accommodate session cookies and function metadata in place of function argument. fentry/fexit programs consume corresponding function metadata. This mirrors existing x86 behavior and enable session cookies on powerpc64.
Patch rebased over: https://lore.kernel.org/bpf/[email protected]/T/#mf02cad9096fa4ad1f05610b1f464da1cddf7445a Signed-off-by: Abhishek Dubey <[email protected]> --- arch/powerpc/net/bpf_jit.h | 4 +- arch/powerpc/net/bpf_jit_comp.c | 68 ++++++++++++++++++++++++++----- arch/powerpc/net/bpf_jit_comp64.c | 25 ++++++++++++ 3 files changed, 85 insertions(+), 12 deletions(-) diff --git a/arch/powerpc/net/bpf_jit.h b/arch/powerpc/net/bpf_jit.h index 5a115c54e43a..884027343da8 100644 --- a/arch/powerpc/net/bpf_jit.h +++ b/arch/powerpc/net/bpf_jit.h @@ -217,7 +217,9 @@ void bpf_jit_build_epilogue(u32 *image, struct codegen_context *ctx); void bpf_jit_build_fentry_stubs(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); - +void prepare_for_fsession_fentry(u32 *image, struct codegen_context *ctx, int cookie_cnt, + int cookie_off, int retval_off); +void store_func_meta(u32 *image, struct codegen_context *ctx, u64 func_meta, int func_meta_off); int bpf_add_extable_entry(struct bpf_prog *fp, u32 *image, u32 *fimage, int pass, struct codegen_context *ctx, int insn_idx, int jmp_off, int dst_reg, u32 code); diff --git a/arch/powerpc/net/bpf_jit_comp.c b/arch/powerpc/net/bpf_jit_comp.c index 629c263a054b..65e091064fe4 100644 --- a/arch/powerpc/net/bpf_jit_comp.c +++ b/arch/powerpc/net/bpf_jit_comp.c @@ -527,6 +527,11 @@ bool bpf_jit_supports_private_stack(void) return IS_ENABLED(CONFIG_PPC64); } +bool bpf_jit_supports_fsession(void) +{ + return IS_ENABLED(CONFIG_PPC64); +} + bool bpf_jit_supports_arena(void) { return IS_ENABLED(CONFIG_PPC64); @@ -798,12 +803,15 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *rw_im struct bpf_tramp_links *tlinks, void *func_addr) { - int regs_off, nregs_off, ip_off, run_ctx_off, retval_off, nvr_off, alt_lr_off, r4_off = 0; + int regs_off, func_meta_off, ip_off, run_ctx_off, retval_off, nvr_off, alt_lr_off, r4_off = 0; struct bpf_tramp_links *fmod_ret = &tlinks[BPF_TRAMP_MODIFY_RETURN]; struct bpf_tramp_links *fentry = &tlinks[BPF_TRAMP_FENTRY]; struct bpf_tramp_links *fexit = &tlinks[BPF_TRAMP_FEXIT]; int i, ret, nr_regs, retaddr_off, bpf_frame_size = 0; struct codegen_context codegen_ctx, *ctx; + int cookie_off, cookie_cnt, cookie_ctx_off; + int fsession_cnt = bpf_fsession_cnt(tlinks); + u64 func_meta; u32 *image = (u32 *)rw_image; ppc_inst_t branch_insn; u32 *branches = NULL; @@ -839,9 +847,11 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *rw_im * [ reg argN ] * [ ... ] * regs_off [ reg_arg1 ] prog ctx context - * nregs_off [ args count ] ((u64 *)prog_ctx)[-1] + * func_meta_off [ args count ] ((u64 *)prog_ctx)[-1] * ip_off [ traced function ] ((u64 *)prog_ctx)[-2] - * [ ... ] + * [ stack cookieN ] + * [ ... ] + * cookie_off [ stack cookie1 ] * run_ctx_off [ bpf_tramp_run_ctx ] * [ reg argN ] * [ ... ] @@ -873,16 +883,21 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *rw_im run_ctx_off = bpf_frame_size; bpf_frame_size += round_up(sizeof(struct bpf_tramp_run_ctx), SZL); + /* room for session cookies */ + cookie_off = bpf_frame_size; + cookie_cnt = bpf_fsession_cookie_cnt(tlinks); + bpf_frame_size += cookie_cnt * 8; + /* Room for IP address argument */ ip_off = bpf_frame_size; if (flags & BPF_TRAMP_F_IP_ARG) bpf_frame_size += SZL; - /* Room for args count */ - nregs_off = bpf_frame_size; + /* Room for function metadata, arg regs count */ + func_meta_off = bpf_frame_size; bpf_frame_size += SZL; - /* Room for args */ + /* Room for arg egs */ regs_off = bpf_frame_size; bpf_frame_size += nr_regs * SZL; @@ -976,9 +991,9 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *rw_im EMIT(PPC_RAW_STL(_R3, _R1, retaddr_off)); } - /* Save function arg count -- see bpf_get_func_arg_cnt() */ - EMIT(PPC_RAW_LI(_R3, nr_regs)); - EMIT(PPC_RAW_STL(_R3, _R1, nregs_off)); + /* Save function arg regs count -- see bpf_get_func_arg_cnt() */ + func_meta = nr_regs; + store_func_meta(image, ctx, func_meta, func_meta_off); /* Save nv regs */ EMIT(PPC_RAW_STL(_R25, _R1, nvr_off)); @@ -992,10 +1007,27 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *rw_im return ret; } - for (i = 0; i < fentry->nr_links; i++) + if (fsession_cnt) { + /* + * Clear all the session cookies' values + * Clear the return value to make sure fentry always get 0 + */ + prepare_for_fsession_fentry(image, ctx, cookie_cnt, cookie_off, retval_off); + } + + cookie_ctx_off = (regs_off - cookie_off) / 8; + + for (i = 0; i < fentry->nr_links; i++) { + if (bpf_prog_calls_session_cookie(fentry->links[i])) { + u64 meta = func_meta | (cookie_ctx_off << BPF_TRAMP_COOKIE_INDEX_SHIFT); + store_func_meta(image, ctx, meta, func_meta_off); + cookie_ctx_off--; + } + if (invoke_bpf_prog(image, ro_image, ctx, fentry->links[i], regs_off, retval_off, run_ctx_off, flags & BPF_TRAMP_F_RET_FENTRY_RET)) return -EINVAL; + } if (fmod_ret->nr_links) { branches = kcalloc(fmod_ret->nr_links, sizeof(u32), GFP_KERNEL); @@ -1057,12 +1089,26 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *rw_im image[branches[i]] = ppc_inst_val(branch_insn); } - for (i = 0; i < fexit->nr_links; i++) + /* set the "is_return" flag for fsession */ + func_meta |= (1ULL << BPF_TRAMP_IS_RETURN_SHIFT); + if (fsession_cnt) + store_func_meta(image, ctx, func_meta, func_meta_off); + + cookie_ctx_off = (regs_off - cookie_off) / 8; + + for (i = 0; i < fexit->nr_links; i++) { + if (bpf_prog_calls_session_cookie(fexit->links[i])) { + u64 meta = func_meta | (cookie_ctx_off << BPF_TRAMP_COOKIE_INDEX_SHIFT); + store_func_meta(image, ctx, meta, func_meta_off); + cookie_ctx_off--; + } + if (invoke_bpf_prog(image, ro_image, ctx, fexit->links[i], regs_off, retval_off, run_ctx_off, false)) { ret = -EINVAL; goto cleanup; } + } if (flags & BPF_TRAMP_F_CALL_ORIG) { if (ro_image) /* image is NULL for dummy pass */ diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c index 206ef43b4090..1b397715206d 100644 --- a/arch/powerpc/net/bpf_jit_comp64.c +++ b/arch/powerpc/net/bpf_jit_comp64.c @@ -179,6 +179,31 @@ static int bpf_jit_stack_offsetof(struct codegen_context *ctx, int reg) BUG(); } +void prepare_for_fsession_fentry(u32 *image, struct codegen_context *ctx, int cookie_cnt, + int cookie_off, int retval_off) +{ + EMIT(PPC_RAW_LI(bpf_to_ppc(TMP_REG_1), 0)); + + for (int i = 0; i < cookie_cnt; i++) + EMIT(PPC_RAW_STD(bpf_to_ppc(TMP_REG_1), _R1, cookie_off + 8 * i)); + EMIT(PPC_RAW_STD(bpf_to_ppc(TMP_REG_1), _R1, retval_off)); +} + +void store_func_meta(u32 *image, struct codegen_context *ctx, + u64 func_meta, int func_meta_off) +{ + /* + * Store func_meta to stack at [R1 + func_meta_off] = func_meta + * + * func_meta : + * bit[63]: is_return flag + * byte[1]: cookie offset from ctx + * byte[0]: args count + */ + PPC_LI64(bpf_to_ppc(TMP_REG_1), func_meta); + EMIT(PPC_RAW_STD(bpf_to_ppc(TMP_REG_1), _R1, func_meta_off)); +} + void bpf_jit_realloc_regs(struct codegen_context *ctx) { } -- 2.52.0
