From 343949e10798a52c6d6a14effc962e010ed471ae Mon Sep 17 00:00:00 2001 From: Benjamin Tissoires Date: Wed, 24 Aug 2022 15:40:37 +0200 Subject: libbpf: add map_get_fd_by_id and map_delete_elem in light skeleton This allows to have a better control over maps from the kernel when preloading eBPF programs. Acked-by: Yonghong Song Signed-off-by: Benjamin Tissoires Link: https://lore.kernel.org/r/20220824134055.1328882-8-benjamin.tissoires@redhat.com Signed-off-by: Alexei Starovoitov --- tools/lib/bpf/skel_internal.h | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) (limited to 'tools/lib') diff --git a/tools/lib/bpf/skel_internal.h b/tools/lib/bpf/skel_internal.h index 00c5f94b43be..1e82ab06c3eb 100644 --- a/tools/lib/bpf/skel_internal.h +++ b/tools/lib/bpf/skel_internal.h @@ -251,6 +251,29 @@ static inline int skel_map_update_elem(int fd, const void *key, return skel_sys_bpf(BPF_MAP_UPDATE_ELEM, &attr, attr_sz); } +static inline int skel_map_delete_elem(int fd, const void *key) +{ + const size_t attr_sz = offsetofend(union bpf_attr, flags); + union bpf_attr attr; + + memset(&attr, 0, attr_sz); + attr.map_fd = fd; + attr.key = (long)key; + + return skel_sys_bpf(BPF_MAP_DELETE_ELEM, &attr, attr_sz); +} + +static inline int skel_map_get_fd_by_id(__u32 id) +{ + const size_t attr_sz = offsetofend(union bpf_attr, flags); + union bpf_attr attr; + + memset(&attr, 0, attr_sz); + attr.map_id = id; + + return skel_sys_bpf(BPF_MAP_GET_FD_BY_ID, &attr, attr_sz); +} + static inline int skel_raw_tracepoint_open(const char *name, int prog_fd) { const size_t attr_sz = offsetofend(union bpf_attr, raw_tracepoint.prog_fd); -- cgit v1.2.3-70-g09d2 From 14e5ce79943a72b9bf0fff8a5867320a9fa3e40d Mon Sep 17 00:00:00 2001 From: James Hilliard Date: Mon, 29 Aug 2022 15:05:46 -0600 Subject: libbpf: Add GCC support for bpf_tail_call_static The bpf_tail_call_static function is currently not defined unless using clang >= 8. To support bpf_tail_call_static on GCC we can check if __clang__ is not defined to enable bpf_tail_call_static. We need to use GCC assembly syntax when the compiler does not define __clang__ as LLVM inline assembly is not fully compatible with GCC. Signed-off-by: James Hilliard Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20220829210546.755377-1-james.hilliard1@gmail.com --- tools/lib/bpf/bpf_helpers.h | 19 +++++++++++++------ 1 file changed, 13 insertions(+), 6 deletions(-) (limited to 'tools/lib') diff --git a/tools/lib/bpf/bpf_helpers.h b/tools/lib/bpf/bpf_helpers.h index 7349b16b8e2f..867b734839dd 100644 --- a/tools/lib/bpf/bpf_helpers.h +++ b/tools/lib/bpf/bpf_helpers.h @@ -131,7 +131,7 @@ /* * Helper function to perform a tail call with a constant/immediate map slot. */ -#if __clang_major__ >= 8 && defined(__bpf__) +#if (!defined(__clang__) || __clang_major__ >= 8) && defined(__bpf__) static __always_inline void bpf_tail_call_static(void *ctx, const void *map, const __u32 slot) { @@ -139,8 +139,8 @@ bpf_tail_call_static(void *ctx, const void *map, const __u32 slot) __bpf_unreachable(); /* - * Provide a hard guarantee that LLVM won't optimize setting r2 (map - * pointer) and r3 (constant map index) from _different paths_ ending + * Provide a hard guarantee that the compiler won't optimize setting r2 + * (map pointer) and r3 (constant map index) from _different paths_ ending * up at the _same_ call insn as otherwise we won't be able to use the * jmpq/nopl retpoline-free patching by the x86-64 JIT in the kernel * given they mismatch. See also d2e4c1e6c294 ("bpf: Constant map key @@ -148,12 +148,19 @@ bpf_tail_call_static(void *ctx, const void *map, const __u32 slot) * * Note on clobber list: we need to stay in-line with BPF calling * convention, so even if we don't end up using r0, r4, r5, we need - * to mark them as clobber so that LLVM doesn't end up using them - * before / after the call. + * to mark them as clobber so that the compiler doesn't end up using + * them before / after the call. */ - asm volatile("r1 = %[ctx]\n\t" + asm volatile( +#ifdef __clang__ + "r1 = %[ctx]\n\t" "r2 = %[map]\n\t" "r3 = %[slot]\n\t" +#else + "mov %%r1,%[ctx]\n\t" + "mov %%r2,%[map]\n\t" + "mov %%r3,%[slot]\n\t" +#endif "call 12" :: [ctx]"r"(ctx), [map]"r"(map), [slot]"i"(slot) : "r0", "r1", "r2", "r3", "r4", "r5"); -- cgit v1.2.3-70-g09d2