// SPDX-License-Identifier: GPL-2.0 #include #include #include #include "../../../include/linux/filter.h" #include "bpf_misc.h" #include #include "bpf_kfuncs.h" SEC("raw_tp") __arch_x86_64 __log_level(4) __msg("stack depth 8") __xlated("4: r5 = 5") __xlated("5: w0 = ") __xlated("6: r0 = &(void __percpu *)(r0)") __xlated("7: r0 = *(u32 *)(r0 +0)") __xlated("8: exit") __success __naked void simple(void) { asm volatile ( "r1 = 1;" "r2 = 2;" "r3 = 3;" "r4 = 4;" "r5 = 5;" "*(u64 *)(r10 - 16) = r1;" "*(u64 *)(r10 - 24) = r2;" "*(u64 *)(r10 - 32) = r3;" "*(u64 *)(r10 - 40) = r4;" "*(u64 *)(r10 - 48) = r5;" "call %[bpf_get_smp_processor_id];" "r5 = *(u64 *)(r10 - 48);" "r4 = *(u64 *)(r10 - 40);" "r3 = *(u64 *)(r10 - 32);" "r2 = *(u64 *)(r10 - 24);" "r1 = *(u64 *)(r10 - 16);" "exit;" : : __imm(bpf_get_smp_processor_id) : __clobber_all); } /* The logic for detecting and verifying bpf_fastcall pattern is the same for * any arch, however x86 differs from arm64 or riscv64 in a way * bpf_get_smp_processor_id is rewritten: * - on x86 it is done by verifier * - on arm64 and riscv64 it is done by jit * * Which leads to different xlated patterns for different archs: * - on x86 the call is expanded as 3 instructions * - on arm64 and riscv64 the call remains as is * (but spills/fills are still removed) * * It is really desirable to check instruction indexes in the xlated * patterns, so add this canary test to check that function rewrite by * jit is correctly processed by bpf_fastcall logic, keep the rest of the * tests as x86. */ SEC("raw_tp") __arch_arm64 __arch_riscv64 __xlated("0: r1 = 1") __xlated("1: call bpf_get_smp_processor_id") __xlated("2: exit") __success __naked void canary_arm64_riscv64(void) { asm volatile ( "r1 = 1;" "*(u64 *)(r10 - 16) = r1;" "call %[bpf_get_smp_processor_id];" "r1 = *(u64 *)(r10 - 16);" "exit;" : : __imm(bpf_get_smp_processor_id) : __clobber_all); } SEC("raw_tp") __arch_x86_64 __xlated("1: r0 = &(void __percpu *)(r0)") __xlated("...") __xlated("3: exit") __success __naked void canary_zero_spills(void) { asm volatile ( "call %[bpf_get_smp_processor_id];" "exit;" : : __imm(bpf_get_smp_processor_id) : __clobber_all); } SEC("raw_tp") __arch_x86_64 __log_level(4) __msg("stack depth 16") __xlated("1: *(u64 *)(r10 -16) = r1") __xlated("...") __xlated("3: r0 = &(void __percpu *)(r0)") __xlated("...") __xlated("5: r2 = *(u64 *)(r10 -16)") __success __naked void wrong_reg_in_pattern1(void) { asm volatile ( "r1 = 1;" "*(u64 *)(r10 - 16) = r1;" "call %[bpf_get_smp_processor_id];" "r2 = *(u64 *)(r10 - 16);" "exit;" : : __imm(bpf_get_smp_processor_id) : __clobber_all); } SEC("raw_tp") __arch_x86_64 __xlated("1: *(u64 *)(r10 -16) = r6") __xlated("...") __xlated("3: r0 = &(void __percpu *)(r0)") __xlated("...") __xlated("5: r6 = *(u64 *)(r10 -16)") __success __naked void wrong_reg_in_pattern2(void) { asm volatile ( "r6 = 1;" "*(u64 *)(r10 - 16) = r6;" "call %[bpf_get_smp_processor_id];" "r6 = *(u64 *)(r10 - 16);" "exit;" : : __imm(bpf_get_smp_processor_id) : __clobber_all); } SEC("raw_tp") __arch_x86_64 __xlated("1: *(u64 *)(r10 -16) = r0") __xlated("...") __xlated("3: r0 = &(void __percpu *)(r0)") __xlated("...") __xlated("5: r0 = *(u64 *)(r10 -16)") __success __naked void wrong_reg_in_pattern3(void) { asm volatile ( "r0 = 1;" "*(u64 *)(r10 - 16) = r0;" "call %[bpf_get_smp_processor_id];" "r0 = *(u64 *)(r10 - 16);" "exit;" : : __imm(bpf_get_smp_processor_id) : __clobber_all); } SEC("raw_tp") __arch_x86_64 __xlated("2: *(u64 *)(r2 -16) = r1") __xlated("...") __xlated("4: r0 = &(void __percpu *)(r0)") __xlated("...") __xlated("6: r1 = *(u64 *)(r10 -16)") __success __naked void wrong_base_in_pattern(void) { asm volatile ( "r1 = 1;" "r2 = r10;" "*(u64 *)(r2 - 16) = r1;" "call %[bpf_get_smp_processor_id];" "r1 = *(u64 *)(r10 - 16);" "exit;" : : __imm(bpf_get_smp_processor_id) : __clobber_all); } SEC("raw_tp") __arch_x86_64 __xlated("1: *(u64 *)(r10 -16) = r1") __xlated("...") __xlated("3: r0 = &(void __percpu *)(r0)") __xlated("...") __xlated("5: r2 = 1") __success __naked void wrong_insn_in_pattern(void) { asm volatile ( "r1 = 1;" "*(u64 *)(r10 - 16) = r1;" "call %[bpf_get_smp_processor_id];" "r2 = 1;" "r1 = *(u64 *)(r10 - 16);" "exit;" : : __imm(bpf_get_smp_processor_id) : __clobber_all); } SEC("raw_tp") __arch_x86_64 __xlated("2: *(u64 *)(r10 -16) = r1") __xlated("...") __xlated("4: r0 = &(void __percpu *)(r0)") __xlated("...") __xlated("6: r1 = *(u64 *)(r10 -8)") __success __naked void wrong_off_in_pattern1(void) { asm volatile ( "r1 = 1;" "*(u64 *)(r10 - 8) = r1;" "*(u64 *)(r10 - 16) = r1;" "call %[bpf_get_smp_processor_id];" "r1 = *(u64 *)(r10 - 8);" "exit;" : : __imm(bpf_get_smp_processor_id) : __clobber_all); } SEC("raw_tp") __arch_x86_64 __xlated("1: *(u32 *)(r10 -4) = r1") __xlated("...") __xlated("3: r0 = &(void __percpu *)(r0)") __xlated("...") __xlated("5: r1 = *(u32 *)(r10 -4)") __success __naked void wrong_off_in_pattern2(void) { asm volatile ( "r1 = 1;" "*(u32 *)(r10 - 4) = r1;" "call %[bpf_get_smp_processor_id];" "r1 = *(u32 *)(r10 - 4);" "exit;" : : __imm(bpf_get_smp_processor_id) : __clobber_all); } SEC("raw_tp") __arch_x86_64 __xlated("1: *(u32 *)(r10 -16) = r1") __xlated("...") __xlated("3: r0 = &(void __percpu *)(r0)") __xlated("...") __xlated("5: r1 = *(u32 *)(r10 -16)") __success __naked void wrong_size_in_pattern(void) { asm volatile ( "r1 = 1;" "*(u32 *)(r10 - 16) = r1;" "call %[bpf_get_smp_processor_id];" "r1 = *(u32 *)(r10 - 16);" "exit;" : : __imm(bpf_get_smp_processor_id) : __clobber_all); } SEC("raw_tp") __arch_x86_64 __xlated("2: *(u32 *)(r10 -8) = r1") __xlated("...") __xlated("4: r0 = &(void __percpu *)(r0)") __xlated("...") __xlated("6: r1 = *(u32 *)(r10 -8)") __success __naked void partial_pattern(void) { asm volatile ( "r1 = 1;" "r2 = 2;" "*(u32 *)(r10 - 8) = r1;" "*(u64 *)(r10 - 16) = r2;" "call %[bpf_get_smp_processor_id];" "r2 = *(u64 *)(r10 - 16);" "r1 = *(u32 *)(r10 - 8);" "exit;" : : __imm(bpf_get_smp_processor_id) : __clobber_all); } SEC("raw_tp") __arch_x86_64 __xlated("0: r1 = 1") __xlated("1: r2 = 2") /* not patched, spills for -8, -16 not removed */ __xlated("2: *(u64 *)(r10 -8) = r1") __xlated("3: *(u64 *)(r10 -16) = r2") __xlated("...") __xlated("5: r0 = &(void __percpu *)(r0)") __xlated("...") __xlated("7: r2 = *(u64 *)(r10 -16)") __xlated("8: r1 = *(u64 *)(r10 -8)") /* patched, spills for -24, -32 removed */ __xlated("...") __xlated("10: r0 = &(void __percpu *)(r0)") __xlated("...") __xlated("12: exit") __success __naked void min_stack_offset(void) { asm volatile ( "r1 = 1;" "r2 = 2;" /* this call won't be patched */ "*(u64 *)(r10 - 8) = r1;" "*(u64 *)(r10 - 16) = r2;" "call %[bpf_get_smp_processor_id];" "r2 = *(u64 *)(r10 - 16);" "r1 = *(u64 *)(r10 - 8);" /* this call would be patched */ "*(u64 *)(r10 - 24) = r1;" "*(u64 *)(r10 - 32) = r2;" "call %[bpf_get_smp_processor_id];" "r2 = *(u64 *)(r10 - 32);" "r1 = *(u64 *)(r10 - 24);" "exit;" : : __imm(bpf_get_smp_processor_id) : __clobber_all); } SEC("raw_tp") __arch_x86_64 __xlated("1: *(u64 *)(r10 -8) = r1") __xlated("...") __xlated("3: r0 = &(void __percpu *)(r0)") __xlated("...") __xlated("5: r1 = *(u64 *)(r10 -8)") __success __naked void bad_fixed_read(void) { asm volatile ( "r1 = 1;" "*(u64 *)(r10 - 8) = r1;" "call %[bpf_get_smp_processor_id];" "r1 = *(u64 *)(r10 - 8);" "r1 = r10;" "r1 += -8;" "r1 = *(u64 *)(r1 - 0);" "exit;" : : __imm(bpf_get_smp_processor_id) : __clobber_all); } SEC("raw_tp") __arch_x86_64 __xlated("1: *(u64 *)(r10 -8) = r1") __xlated("...") __xlated("3: r0 = &(void __percpu *)(r0)") __xlated("...") __xlated("5: r1 = *(u64 *)(r10 -8)") __success __naked void bad_fixed_write(void) { asm volatile ( "r1 = 1;" "*(u64 *)(r10 - 8) = r1;" "call %[bpf_get_smp_processor_id];" "r1 = *(u64 *)(r10 - 8);" "r1 = r10;" "r1 += -8;" "*(u64 *)(r1 - 0) = r1;" "exit;" : : __imm(bpf_get_smp_processor_id) : __clobber_all); } SEC("raw_tp") __arch_x86_64 __xlated("6: *(u64 *)(r10 -16) = r1") __xlated("...") __xlated("8: r0 = &(void __percpu *)(r0)") __xlated("...") __xlated("10: r1 = *(u64 *)(r10 -16)") __success __naked void bad_varying_read(void) { asm volatile ( "r6 = *(u64 *)(r1 + 0);" /* random scalar value */ "r6 &= 0x7;" /* r6 range [0..7] */ "r6 += 0x2;" /* r6 range [2..9] */ "r7 = 0;" "r7 -= r6;" /* r7 range [-9..-2] */ "r1 = 1;" "*(u64 *)(r10 - 16) = r1;" "call %[bpf_get_smp_processor_id];" "r1 = *(u64 *)(r10 - 16);" "r1 = r10;" "r1 += r7;" "r1 = *(u8 *)(r1 - 0);" /* touches slot [-16..-9] where spills are stored */ "exit;" : : __imm(bpf_get_smp_processor_id) : __clobber_all); } SEC("raw_tp") __arch_x86_64 __xlated("6: *(u64 *)(r10 -16) = r1") __xlated("...") __xlated("8: r0 = &(void __percpu *)(r0)") __xlated("...") __xlated("10: r1 = *(u64 *)(r10 -16)") __success __naked void bad_varying_write(void) { asm volatile ( "r6 = *(u64 *)(r1 + 0);" /* random scalar value */ "r6 &= 0x7;" /* r6 range [0..7] */ "r6 += 0x2;" /* r6 range [2..9] */ "r7 = 0;" "r7 -= r6;" /* r7 range [-9..-2] */ "r1 = 1;" "*(u64 *)(r10 - 16) = r1;" "call %[bpf_get_smp_processor_id];" "r1 = *(u64 *)(r10 - 16);" "r1 = r10;" "r1 += r7;" "*(u8 *)(r1 - 0) = r7;" /* touches slot [-16..-9] where spills are stored */ "exit;" : : __imm(bpf_get_smp_processor_id) : __clobber_all); } SEC("raw_tp") __arch_x86_64 __xlated("1: *(u64 *)(r10 -8) = r1") __xlated("...") __xlated("3: r0 = &(void __percpu *)(r0)") __xlated("...") __xlated("5: r1 = *(u64 *)(r10 -8)") __success __naked void bad_write_in_subprog(void) { asm volatile ( "r1 = 1;" "*(u64 *)(r10 - 8) = r1;" "call %[bpf_get_smp_processor_id];" "r1 = *(u64 *)(r10 - 8);" "r1 = r10;" "r1 += -8;" "call bad_write_in_subprog_aux;" "exit;" : : __imm(bpf_get_smp_processor_id) : __clobber_all); } __used __naked static void bad_write_in_subprog_aux(void) { asm volatile ( "r0 = 1;" "*(u64 *)(r1 - 0) = r0;" /* invalidates bpf_fastcall contract for caller: */ "exit;" /* caller stack at -8 used outside of the pattern */ ::: __clobber_all); } SEC("raw_tp") __arch_x86_64 __xlated("1: *(u64 *)(r10 -8) = r1") __xlated("...") __xlated("3: r0 = &(void __percpu *)(r0)") __xlated("...") __xlated("5: r1 = *(u64 *)(r10 -8)") __success __naked void bad_helper_write(void) { asm volatile ( "r1 = 1;" /* bpf_fastcall pattern with stack offset -8 */ "*(u64 *)(r10 - 8) = r1;" "call %[bpf_get_smp_processor_id];" "r1 = *(u64 *)(r10 - 8);" "r1 = r10;" "r1 += -8;" "r2 = 1;" "r3 = 42;" /* read dst is fp[-8], thus bpf_fastcall rewrite not applied */ "call %[bpf_probe_read_kernel];" "exit;" : : __imm(bpf_get_smp_processor_id), __imm(bpf_probe_read_kernel) : __clobber_all); } SEC("raw_tp") __arch_x86_64 /* main, not patched */ __xlated("1: *(u64 *)(r10 -8) = r1") __xlated("...") __xlated("3: r0 = &(void __percpu *)(r0)") __xlated("...") __xlated("5: r1 = *(u64 *)(r10 -8)") __xlated("...") __xlated("9: call pc+1") __xlated("...") __xlated("10: exit") /* subprogram, patched */ __xlated("11: r1 = 1") __xlated("...") __xlated("13: r0 = &(void __percpu *)(r0)") __xlated("...") __xlated("15: exit") __success __naked void invalidate_one_subprog(void) { asm volatile ( "r1 = 1;" "*(u64 *)(r10 - 8) = r1;" "call %[bpf_get_smp_processor_id];" "r1 = *(u64 *)(r10 - 8);" "r1 = r10;" "r1 += -8;" "r1 = *(u64 *)(r1 - 0);" "call invalidate_one_subprog_aux;" "exit;" : : __imm(bpf_get_smp_processor_id) : __clobber_all); } __used __naked static void invalidate_one_subprog_aux(void) { asm volatile ( "r1 = 1;" "*(u64 *)(r10 - 8) = r1;" "call %[bpf_get_smp_processor_id];" "r1 = *(u64 *)(r10 - 8);" "exit;" : : __imm(bpf_get_smp_processor_id) : __clobber_all); } SEC("raw_tp") __arch_x86_64 /* main */ __xlated("0: r1 = 1") __xlated("...") __xlated("2: r0 = &(void __percpu *)(r0)") __xlated("...") __xlated("4: call pc+1") __xlated("5: exit") /* subprogram */ __xlated("6: r1 = 1") __xlated("...") __xlated("8: r0 = &(void __percpu *)(r0)") __xlated("...") __xlated("10: *(u64 *)(r10 -16) = r1") __xlated("11: exit") __success __naked void subprogs_use_independent_offsets(void) { asm volatile ( "r1 = 1;" "*(u64 *)(r10 - 16) = r1;" "call %[bpf_get_smp_processor_id];" "r1 = *(u64 *)(r10 - 16);" "call subprogs_use_independent_offsets_aux;" "exit;" : : __imm(bpf_get_smp_processor_id) : __clobber_all); } __used __naked static void subprogs_use_independent_offsets_aux(void) { asm volatile ( "r1 = 1;" "*(u64 *)(r10 - 24) = r1;" "call %[bpf_get_smp_processor_id];" "r1 = *(u64 *)(r10 - 24);" "*(u64 *)(r10 - 16) = r1;" "exit;" : : __imm(bpf_get_smp_processor_id) : __clobber_all); } SEC("raw_tp") __arch_x86_64 __log_level(4) __msg("stack depth 8") __xlated("2: r0 = &(void __percpu *)(r0)") __success __naked void helper_call_does_not_prevent_bpf_fastcall(void) { asm volatile ( "r1 = 1;" "*(u64 *)(r10 - 8) = r1;" "call %[bpf_get_smp_processor_id];" "r1 = *(u64 *)(r10 - 8);" "*(u64 *)(r10 - 8) = r1;" "call %[bpf_get_prandom_u32];" "r1 = *(u64 *)(r10 - 8);" "exit;" : : __imm(bpf_get_smp_processor_id), __imm(bpf_get_prandom_u32) : __clobber_all); } SEC("raw_tp") __arch_x86_64 __log_level(4) __msg("stack depth 16") /* may_goto counter at -16 */ __xlated("0: *(u64 *)(r10 -16) =") __xlated("1: r1 = 1") __xlated("...") __xlated("3: r0 = &(void __percpu *)(r0)") __xlated("...") /* may_goto expansion starts */ __xlated("5: r11 = *(u64 *)(r10 -16)") __xlated("6: if r11 == 0x0 goto pc+3") __xlated("7: r11 -= 1") __xlated("8: *(u64 *)(r10 -16) = r11") /* may_goto expansion ends */ __xlated("9: *(u64 *)(r10 -8) = r1") __xlated("10: exit") __success __naked void may_goto_interaction(void) { asm volatile ( "r1 = 1;" "*(u64 *)(r10 - 16) = r1;" "call %[bpf_get_smp_processor_id];" "r1 = *(u64 *)(r10 - 16);" ".8byte %[may_goto];" /* just touch some stack at -8 */ "*(u64 *)(r10 - 8) = r1;" "exit;" : : __imm(bpf_get_smp_processor_id), __imm_insn(may_goto, BPF_RAW_INSN(BPF_JMP | BPF_JCOND, 0, 0, +1 /* offset */, 0)) : __clobber_all); } __used __naked static void dummy_loop_callback(void) { asm volatile ( "r0 = 0;" "exit;" ::: __clobber_all); } SEC("raw_tp") __arch_x86_64 __log_level(4) __msg("stack depth 32+0") __xlated("2: r1 = 1") __xlated("3: w0 =") __xlated("4: r0 = &(void __percpu *)(r0)") __xlated("5: r0 = *(u32 *)(r0 +0)") /* bpf_loop params setup */ __xlated("6: r2 =") __xlated("7: r3 = 0") __xlated("8: r4 = 0") __xlated("...") /* ... part of the inlined bpf_loop */ __xlated("12: *(u64 *)(r10 -32) = r6") __xlated("13: *(u64 *)(r10 -24) = r7") __xlated("14: *(u64 *)(r10 -16) = r8") __xlated("...") __xlated("21: call pc+8") /* dummy_loop_callback */ /* ... last insns of the bpf_loop_interaction1 */ __xlated("...") __xlated("28: r0 = 0") __xlated("29: exit") /* dummy_loop_callback */ __xlated("30: r0 = 0") __xlated("31: exit") __success __naked int bpf_loop_interaction1(void) { asm volatile ( "r1 = 1;" /* bpf_fastcall stack region at -16, but could be removed */ "*(u64 *)(r10 - 16) = r1;" "call %[bpf_get_smp_processor_id];" "r1 = *(u64 *)(r10 - 16);" "r2 = %[dummy_loop_callback];" "r3 = 0;" "r4 = 0;" "call %[bpf_loop];" "r0 = 0;" "exit;" : : __imm_ptr(dummy_loop_callback), __imm(bpf_get_smp_processor_id), __imm(bpf_loop) : __clobber_common ); } SEC("raw_tp") __arch_x86_64 __log_level(4) __msg("stack depth 40+0") /* call bpf_get_smp_processor_id */ __xlated("2: r1 = 42") __xlated("3: w0 =") __xlated("4: r0 = &(void __percpu *)(r0)") __xlated("5: r0 = *(u32 *)(r0 +0)") /* call bpf_get_prandom_u32 */ __xlated("6: *(u64 *)(r10 -16) = r1") __xlated("7: call") __xlated("8: r1 = *(u64 *)(r10 -16)") __xlated("...") /* ... part of the inlined bpf_loop */ __xlated("15: *(u64 *)(r10 -40) = r6") __xlated("16: *(u64 *)(r10 -32) = r7") __xlated("17: *(u64 *)(r10 -24) = r8") __success __naked int bpf_loop_interaction2(void) { asm volatile ( "r1 = 42;" /* bpf_fastcall stack region at -16, cannot be removed */ "*(u64 *)(r10 - 16) = r1;" "call %[bpf_get_smp_processor_id];" "r1 = *(u64 *)(r10 - 16);" "*(u64 *)(r10 - 16) = r1;" "call %[bpf_get_prandom_u32];" "r1 = *(u64 *)(r10 - 16);" "r2 = %[dummy_loop_callback];" "r3 = 0;" "r4 = 0;" "call %[bpf_loop];" "r0 = 0;" "exit;" : : __imm_ptr(dummy_loop_callback), __imm(bpf_get_smp_processor_id), __imm(bpf_get_prandom_u32), __imm(bpf_loop) : __clobber_common ); } SEC("raw_tp") __arch_x86_64 __log_level(4) __msg("stack depth 512+0") /* just to print xlated version when debugging */ __xlated("r0 = &(void __percpu *)(r0)") __success /* cumulative_stack_depth() stack usage is MAX_BPF_STACK, * called subprogram uses an additional slot for bpf_fastcall spill/fill, * since bpf_fastcall spill/fill could be removed the program still fits * in MAX_BPF_STACK and should be accepted. */ __naked int cumulative_stack_depth(void) { asm volatile( "r1 = 42;" "*(u64 *)(r10 - %[max_bpf_stack]) = r1;" "call cumulative_stack_depth_subprog;" "exit;" : : __imm_const(max_bpf_stack, MAX_BPF_STACK) : __clobber_all ); } __used __naked static void cumulative_stack_depth_subprog(void) { asm volatile ( "*(u64 *)(r10 - 8) = r1;" "call %[bpf_get_smp_processor_id];" "r1 = *(u64 *)(r10 - 8);" "exit;" :: __imm(bpf_get_smp_processor_id) : __clobber_all); } SEC("cgroup/getsockname_unix") __xlated("0: r2 = 1") /* bpf_cast_to_kern_ctx is replaced by a single assignment */ __xlated("1: r0 = r1") __xlated("2: r0 = r2") __xlated("3: exit") __success __naked void kfunc_bpf_cast_to_kern_ctx(void) { asm volatile ( "r2 = 1;" "*(u64 *)(r10 - 32) = r2;" "call %[bpf_cast_to_kern_ctx];" "r2 = *(u64 *)(r10 - 32);" "r0 = r2;" "exit;" : : __imm(bpf_cast_to_kern_ctx) : __clobber_all); } SEC("raw_tp") __xlated("3: r3 = 1") /* bpf_rdonly_cast is replaced by a single assignment */ __xlated("4: r0 = r1") __xlated("5: r0 = r3") void kfunc_bpf_rdonly_cast(void) { asm volatile ( "r2 = %[btf_id];" "r3 = 1;" "*(u64 *)(r10 - 32) = r3;" "call %[bpf_rdonly_cast];" "r3 = *(u64 *)(r10 - 32);" "r0 = r3;" : : __imm(bpf_rdonly_cast), [btf_id]"r"(bpf_core_type_id_kernel(union bpf_attr)) : __clobber_common); } /* BTF FUNC records are not generated for kfuncs referenced * from inline assembly. These records are necessary for * libbpf to link the program. The function below is a hack * to ensure that BTF FUNC records are generated. */ void kfunc_root(void) { bpf_cast_to_kern_ctx(0); bpf_rdonly_cast(0, 0); } char _license[] SEC("license") = "GPL";