On Mon, Jan 05, 2026 at 04:22:11PM +0530, [email protected] wrote: > From: Abhishek Dubey <[email protected]> > > The modified prologue/epilogue generation code now > enables exception-callback to use the stack frame of > the program marked as exception boundary, where callee > saved registers are stored. > > As per ppc64 ABIv2 documentation[1], r14-r31 are callee > saved registers. BPF programs on ppc64 already saves > r26-r31 registers. Saving the remaining set of callee > saved registers(r14-r25) is handled in the next patch. > > [1] > https://ftp.rtems.org/pub/rtems/people/sebh/ABI64BitOpenPOWERv1.1_16July2015_pub.pdf > > Following is exceptions selftest result on ppc64le: > > # ./test_progs -t exceptions > #100/1 exceptions/exception_throw_always_1:OK > #100/2 exceptions/exception_throw_always_2:OK > #100/3 exceptions/exception_throw_unwind_1:OK > #100/4 exceptions/exception_throw_unwind_2:OK > #100/5 exceptions/exception_throw_default:OK > #100/6 exceptions/exception_throw_default_value:OK > #100/7 exceptions/exception_tail_call:OK > #100/8 exceptions/exception_ext:OK > #100/9 exceptions/exception_ext_mod_cb_runtime:OK > #100/10 exceptions/exception_throw_subprog:OK > #100/11 exceptions/exception_assert_nz_gfunc:OK > #100/12 exceptions/exception_assert_zero_gfunc:OK > #100/13 exceptions/exception_assert_neg_gfunc:OK > #100/14 exceptions/exception_assert_pos_gfunc:OK > #100/15 exceptions/exception_assert_negeq_gfunc:OK > #100/16 exceptions/exception_assert_poseq_gfunc:OK > #100/17 exceptions/exception_assert_nz_gfunc_with:OK > #100/18 exceptions/exception_assert_zero_gfunc_with:OK > #100/19 exceptions/exception_assert_neg_gfunc_with:OK > #100/20 exceptions/exception_assert_pos_gfunc_with:OK > #100/21 exceptions/exception_assert_negeq_gfunc_with:OK > #100/22 exceptions/exception_assert_poseq_gfunc_with:OK > #100/23 exceptions/exception_bad_assert_nz_gfunc:OK > #100/24 exceptions/exception_bad_assert_zero_gfunc:OK > #100/25 exceptions/exception_bad_assert_neg_gfunc:OK > #100/26 exceptions/exception_bad_assert_pos_gfunc:OK > #100/27 exceptions/exception_bad_assert_negeq_gfunc:OK > #100/28 exceptions/exception_bad_assert_poseq_gfunc:OK > #100/29 exceptions/exception_bad_assert_nz_gfunc_with:OK > #100/30 exceptions/exception_bad_assert_zero_gfunc_with:OK > #100/31 exceptions/exception_bad_assert_neg_gfunc_with:OK > #100/32 exceptions/exception_bad_assert_pos_gfunc_with:OK > #100/33 exceptions/exception_bad_assert_negeq_gfunc_with:OK > #100/34 exceptions/exception_bad_assert_poseq_gfunc_with:OK > #100/35 exceptions/exception_assert_range:OK > #100/36 exceptions/exception_assert_range_with:OK > #100/37 exceptions/exception_bad_assert_range:OK > #100/38 exceptions/exception_bad_assert_range_with:OK > #100/39 exceptions/non-throwing fentry -> exception_cb:OK > #100/40 exceptions/throwing fentry -> exception_cb:OK > #100/41 exceptions/non-throwing fexit -> exception_cb:OK > #100/42 exceptions/throwing fexit -> exception_cb:OK > #100/43 exceptions/throwing extension (with custom cb) -> exception_cb:OK > #100/44 exceptions/throwing extension -> global func in exception_cb:OK > #100/45 exceptions/exception_ext_mod_cb_runtime:OK > #100/46 exceptions/throwing extension (with custom cb) -> global func in > exception_cb:OK > #100/47 exceptions/exception_ext:OK > #100/48 exceptions/non-throwing fentry -> non-throwing subprog:OK > #100/49 exceptions/throwing fentry -> non-throwing subprog:OK > #100/50 exceptions/non-throwing fentry -> throwing subprog:OK > #100/51 exceptions/throwing fentry -> throwing subprog:OK > #100/52 exceptions/non-throwing fexit -> non-throwing subprog:OK > #100/53 exceptions/throwing fexit -> non-throwing subprog:OK > #100/54 exceptions/non-throwing fexit -> throwing subprog:OK > #100/55 exceptions/throwing fexit -> throwing subprog:OK > #100/56 exceptions/non-throwing fmod_ret -> non-throwing subprog:OK > #100/57 exceptions/non-throwing fmod_ret -> non-throwing global subprog:OK > #100/58 exceptions/non-throwing extension -> non-throwing subprog:OK > #100/59 exceptions/non-throwing extension -> throwing subprog:OK > #100/60 exceptions/non-throwing extension -> non-throwing subprog:OK > #100/61 exceptions/non-throwing extension -> throwing global subprog:OK > #100/62 exceptions/throwing extension -> throwing global subprog:OK > #100/63 exceptions/throwing extension -> non-throwing global subprog:OK > #100/64 exceptions/non-throwing extension -> main subprog:OK > #100/65 exceptions/throwing extension -> main subprog:OK > #100/66 exceptions/reject_exception_cb_type_1:OK > #100/67 exceptions/reject_exception_cb_type_2:OK > #100/68 exceptions/reject_exception_cb_type_3:OK > #100/69 exceptions/reject_exception_cb_type_4:OK > #100/70 exceptions/reject_async_callback_throw:OK > #100/71 exceptions/reject_with_lock:OK > #100/72 exceptions/reject_subprog_with_lock:OK > #100/73 exceptions/reject_with_rcu_read_lock:OK > #100/74 exceptions/reject_subprog_with_rcu_read_lock:OK > #100/75 exceptions/reject_with_rbtree_add_throw:OK > #100/76 exceptions/reject_with_reference:OK > #100/77 exceptions/reject_with_cb_reference:OK > #100/78 exceptions/reject_with_cb:OK > #100/79 exceptions/reject_with_subprog_reference:OK > #100/80 exceptions/reject_throwing_exception_cb:OK > #100/81 exceptions/reject_exception_cb_call_global_func:OK > #100/82 exceptions/reject_exception_cb_call_static_func:OK > #100/83 exceptions/reject_multiple_exception_cb:OK > #100/84 exceptions/reject_exception_throw_cb:OK > #100/85 exceptions/reject_exception_throw_cb_diff:OK > #100/86 exceptions/reject_set_exception_cb_bad_ret1:OK > #100/87 exceptions/reject_set_exception_cb_bad_ret2:OK > #100/88 exceptions/check_assert_eq_int_min:OK > #100/89 exceptions/check_assert_eq_int_max:OK > #100/90 exceptions/check_assert_eq_zero:OK > #100/91 exceptions/check_assert_eq_llong_min:OK > #100/92 exceptions/check_assert_eq_llong_max:OK > #100/93 exceptions/check_assert_lt_pos:OK > #100/94 exceptions/check_assert_lt_zero:OK > #100/95 exceptions/check_assert_lt_neg:OK > #100/96 exceptions/check_assert_le_pos:OK > #100/97 exceptions/check_assert_le_zero:OK > #100/98 exceptions/check_assert_le_neg:OK > #100/99 exceptions/check_assert_gt_pos:OK > #100/100 exceptions/check_assert_gt_zero:OK > #100/101 exceptions/check_assert_gt_neg:OK > #100/102 exceptions/check_assert_ge_pos:OK > #100/103 exceptions/check_assert_ge_zero:OK > #100/104 exceptions/check_assert_ge_neg:OK > #100/105 exceptions/check_assert_range_s64:OK > #100/106 exceptions/check_assert_range_u64:OK > #100/107 exceptions/check_assert_single_range_s64:OK > #100/108 exceptions/check_assert_single_range_u64:OK > #100/109 exceptions/check_assert_generic:OK > #100/110 exceptions/check_assert_with_return:OK > #100 exceptions:OK > Summary: 1/110 PASSED, 0 SKIPPED, 0 FAILED > It would be great to include this selftest output in the cover letter instead, since it makes the git log excessively long.
Thanks, Saket > Signed-off-by: Abhishek Dubey <[email protected]> > --- > arch/powerpc/net/bpf_jit.h | 2 ++ > arch/powerpc/net/bpf_jit_comp.c | 7 ++++ > arch/powerpc/net/bpf_jit_comp64.c | 53 +++++++++++++++++++++---------- > 3 files changed, 45 insertions(+), 17 deletions(-) > > diff --git a/arch/powerpc/net/bpf_jit.h b/arch/powerpc/net/bpf_jit.h > index 98e8b1f9c2f9..b9316780a501 100644 > --- a/arch/powerpc/net/bpf_jit.h > +++ b/arch/powerpc/net/bpf_jit.h > @@ -177,6 +177,8 @@ struct codegen_context { > u64 arena_vm_start; > u64 user_vm_start; > bool is_subprog; > + bool exception_boundary; > + bool exception_cb; > }; > > #define bpf_to_ppc(r) (ctx->b2p[r]) > diff --git a/arch/powerpc/net/bpf_jit_comp.c b/arch/powerpc/net/bpf_jit_comp.c > index b09d294084d4..3c030a7d8e73 100644 > --- a/arch/powerpc/net/bpf_jit_comp.c > +++ b/arch/powerpc/net/bpf_jit_comp.c > @@ -207,6 +207,8 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp) > cgctx.arena_vm_start = bpf_arena_get_kern_vm_start(fp->aux->arena); > cgctx.user_vm_start = bpf_arena_get_user_vm_start(fp->aux->arena); > cgctx.is_subprog = bpf_is_subprog(fp); > + cgctx.exception_boundary = fp->aux->exception_boundary; > + cgctx.exception_cb = fp->aux->exception_cb; > > /* Scouting faux-generate pass 0 */ > if (bpf_jit_build_body(fp, NULL, NULL, &cgctx, addrs, 0, false)) { > @@ -436,6 +438,11 @@ void bpf_jit_free(struct bpf_prog *fp) > bpf_prog_unlock_free(fp); > } > > +bool bpf_jit_supports_exceptions(void) > +{ > + return IS_ENABLED(CONFIG_PPC64); > +} > + > bool bpf_jit_supports_subprog_tailcalls(void) > { > return IS_ENABLED(CONFIG_PPC64); > diff --git a/arch/powerpc/net/bpf_jit_comp64.c > b/arch/powerpc/net/bpf_jit_comp64.c > index 0f3af67914d6..5ec8e3654098 100644 > --- a/arch/powerpc/net/bpf_jit_comp64.c > +++ b/arch/powerpc/net/bpf_jit_comp64.c > @@ -85,7 +85,9 @@ static inline bool bpf_has_stack_frame(struct > codegen_context *ctx) > * - the bpf program uses its stack area > * The latter condition is deduced from the usage of BPF_REG_FP > */ > - return ctx->seen & SEEN_FUNC || bpf_is_seen_register(ctx, > bpf_to_ppc(BPF_REG_FP)); > + return ctx->seen & SEEN_FUNC || > + bpf_is_seen_register(ctx, bpf_to_ppc(BPF_REG_FP)) || > + ctx->exception_cb; > } > > /* > @@ -180,23 +182,32 @@ void bpf_jit_build_prologue(u32 *image, struct > codegen_context *ctx) > EMIT(PPC_RAW_STDU(_R1, _R1, -(BPF_PPC_STACKFRAME + > ctx->stack_size))); > } > > - /* > - * Back up non-volatile regs -- BPF registers 6-10 > - * If we haven't created our own stack frame, we save these > - * in the protected zone below the previous stack frame > - */ > - for (i = BPF_REG_6; i <= BPF_REG_10; i++) > - if (bpf_is_seen_register(ctx, bpf_to_ppc(i))) > - EMIT(PPC_RAW_STD(bpf_to_ppc(i), _R1, > bpf_jit_stack_offsetof(ctx, bpf_to_ppc(i)))); > + if (!ctx->exception_cb) { > + /* > + * Back up non-volatile regs -- BPF registers 6-10 > + * If we haven't created our own stack frame, we save these > + * in the protected zone below the previous stack frame > + */ > + for (i = BPF_REG_6; i <= BPF_REG_10; i++) > + if (ctx->exception_boundary || > bpf_is_seen_register(ctx, bpf_to_ppc(i))) > + EMIT(PPC_RAW_STD(bpf_to_ppc(i), _R1, > + bpf_jit_stack_offsetof(ctx, > bpf_to_ppc(i)))); > > - if (ctx->arena_vm_start) > - EMIT(PPC_RAW_STD(bpf_to_ppc(ARENA_VM_START), _R1, > + if (ctx->exception_boundary || ctx->arena_vm_start) > + EMIT(PPC_RAW_STD(bpf_to_ppc(ARENA_VM_START), _R1, > bpf_jit_stack_offsetof(ctx, > bpf_to_ppc(ARENA_VM_START)))); > > - /* Setup frame pointer to point to the bpf stack area */ > - if (bpf_is_seen_register(ctx, bpf_to_ppc(BPF_REG_FP))) > - EMIT(PPC_RAW_ADDI(bpf_to_ppc(BPF_REG_FP), _R1, > + /* Setup frame pointer to point to the bpf stack area */ > + if (bpf_is_seen_register(ctx, bpf_to_ppc(BPF_REG_FP))) > + EMIT(PPC_RAW_ADDI(bpf_to_ppc(BPF_REG_FP), _R1, > STACK_FRAME_MIN_SIZE + ctx->stack_size)); > + } else { > + /* > + * Exception callback receives Frame Pointer of main > + * program as third arg > + */ > + EMIT(PPC_RAW_MR(_R1, _R5)); > + } > > if (ctx->arena_vm_start) > PPC_LI64(bpf_to_ppc(ARENA_VM_START), ctx->arena_vm_start); > @@ -208,17 +219,25 @@ static void bpf_jit_emit_common_epilogue(u32 *image, > struct codegen_context *ctx > > /* Restore NVRs */ > for (i = BPF_REG_6; i <= BPF_REG_10; i++) > - if (bpf_is_seen_register(ctx, bpf_to_ppc(i))) > + if (ctx->exception_cb || bpf_is_seen_register(ctx, > bpf_to_ppc(i))) > EMIT(PPC_RAW_LD(bpf_to_ppc(i), _R1, > bpf_jit_stack_offsetof(ctx, bpf_to_ppc(i)))); > > - if (ctx->arena_vm_start) > + if (ctx->exception_cb || ctx->arena_vm_start) > EMIT(PPC_RAW_LD(bpf_to_ppc(ARENA_VM_START), _R1, > bpf_jit_stack_offsetof(ctx, > bpf_to_ppc(ARENA_VM_START)))); > > + if (ctx->exception_cb) { > + /* > + * LR value from boundary-frame is received as second parameter > + * in exception callback. > + */ > + EMIT(PPC_RAW_MTLR(_R4)); > + } > + > /* Tear down our stack frame */ > if (bpf_has_stack_frame(ctx)) { > EMIT(PPC_RAW_ADDI(_R1, _R1, BPF_PPC_STACKFRAME + > ctx->stack_size)); > - if (ctx->seen & SEEN_FUNC) { > + if (ctx->seen & SEEN_FUNC || ctx->exception_cb) { > EMIT(PPC_RAW_LD(_R0, _R1, PPC_LR_STKOFF)); > EMIT(PPC_RAW_MTLR(_R0)); > } > -- > 2.48.1 >
