From d045f7682b60332615f3c15185eb4c3bc6274417 Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Thu, 2 May 2024 09:55:40 +0200 Subject: [PATCH 01/12] libbpf: Fix error message in attach_kprobe_session We just failed to retrieve pattern, so we need to print spec instead. Fixes: 2ca178f02b2f ("libbpf: Add support for kprobe session attach") Reported-by: Andrii Nakryiko Signed-off-by: Jiri Olsa Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20240502075541.1425761-1-jolsa@kernel.org --- src/libbpf.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/src/libbpf.c b/src/libbpf.c index 4ffc887..68c87ae 100644 --- a/src/libbpf.c +++ b/src/libbpf.c @@ -11605,7 +11605,7 @@ static int attach_kprobe_session(const struct bpf_program *prog, long cookie, spec = prog->sec_name + sizeof("kprobe.session/") - 1; n = sscanf(spec, "%m[a-zA-Z0-9_.*?]", &pattern); if (n < 1) { - pr_warn("kprobe session pattern is invalid: %s\n", pattern); + pr_warn("kprobe session pattern is invalid: %s\n", spec); return -EINVAL; } From f3c4172c61fb60e035da99337659ee81417ae7f8 Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Thu, 2 May 2024 09:55:41 +0200 Subject: [PATCH 02/12] libbpf: Fix error message in attach_kprobe_multi We just failed to retrieve pattern, so we need to print spec instead. Fixes: ddc6b04989eb ("libbpf: Add bpf_program__attach_kprobe_multi_opts function") Reported-by: Andrii Nakryiko Signed-off-by: Jiri Olsa Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20240502075541.1425761-2-jolsa@kernel.org --- src/libbpf.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/src/libbpf.c b/src/libbpf.c index 68c87ae..a3566a4 100644 --- a/src/libbpf.c +++ b/src/libbpf.c @@ -11579,7 +11579,7 @@ static int attach_kprobe_multi(const struct bpf_program *prog, long cookie, stru n = sscanf(spec, "%m[a-zA-Z0-9_.*?]", &pattern); if (n < 1) { - pr_warn("kprobe multi pattern is invalid: %s\n", pattern); + pr_warn("kprobe multi pattern is invalid: %s\n", spec); return -EINVAL; } From e3e84bd7d01944c4817850bd8e8c3aeedfacedff Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Tue, 30 Apr 2024 13:19:51 -0700 Subject: [PATCH 03/12] libbpf: fix potential overflow in ring__consume_n() ringbuf_process_ring() return int64_t, while ring__consume_n() assigns it to int. It's highly unlikely, but possible for ringbuf_process_ring() to return value larger than INT_MAX, so use int64_t. ring__consume_n() does check INT_MAX before returning int result to the user. Fixes: 4d22ea94ea33 ("libbpf: Add ring__consume_n / ring_buffer__consume_n") Signed-off-by: Andrii Nakryiko Acked-by: Kumar Kartikeya Dwivedi Link: https://lore.kernel.org/r/20240430201952.888293-1-andrii@kernel.org Signed-off-by: Martin KaFai Lau --- src/ringbuf.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/src/ringbuf.c b/src/ringbuf.c index 99e44cf..37c5a2d 100644 --- a/src/ringbuf.c +++ b/src/ringbuf.c @@ -405,7 +405,7 @@ int ring__map_fd(const struct ring *r) int ring__consume_n(struct ring *r, size_t n) { - int res; + int64_t res; res = ringbuf_process_ring(r, n); if (res < 0) From cb7bfc5e515147fe4cc66c0835d70ec9f28df3ae Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Tue, 30 Apr 2024 13:19:52 -0700 Subject: [PATCH 04/12] libbpf: fix ring_buffer__consume_n() return result logic Add INT_MAX check to ring_buffer__consume_n(). We do the similar check to handle int return result of all these ring buffer APIs in other APIs and ring_buffer__consume_n() is missing one. This patch fixes this omission. Signed-off-by: Andrii Nakryiko Acked-by: Kumar Kartikeya Dwivedi Link: https://lore.kernel.org/r/20240430201952.888293-2-andrii@kernel.org Signed-off-by: Martin KaFai Lau --- src/ringbuf.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/src/ringbuf.c b/src/ringbuf.c index 37c5a2d..bfd8dac 100644 --- a/src/ringbuf.c +++ b/src/ringbuf.c @@ -301,7 +301,7 @@ int ring_buffer__consume_n(struct ring_buffer *rb, size_t n) if (n == 0) break; } - return res; + return res > INT_MAX ? INT_MAX : res; } /* Consume available ring buffer(s) data without event polling. From 4ec5e360ae01e8be78e63d7b7e3111e242ba2d21 Mon Sep 17 00:00:00 2001 From: "Jose E. Marchesi" Date: Sun, 28 Apr 2024 13:25:59 +0200 Subject: [PATCH 05/12] libbpf: Fix bpf_ksym_exists() in GCC The macro bpf_ksym_exists is defined in bpf_helpers.h as: #define bpf_ksym_exists(sym) ({ \ _Static_assert(!__builtin_constant_p(!!sym), #sym " should be marked as __weak"); \ !!sym; \ }) The purpose of the macro is to determine whether a given symbol has been defined, given the address of the object associated with the symbol. It also has a compile-time check to make sure the object whose address is passed to the macro has been declared as weak, which makes the check on `sym' meaningful. As it happens, the check for weak doesn't work in GCC in all cases, because __builtin_constant_p not always folds at parse time when optimizing. This is because optimizations that happen later in the compilation process, like inlining, may make a previously non-constant expression a constant. This results in errors like the following when building the selftests with GCC: bpf_helpers.h:190:24: error: expression in static assertion is not constant 190 | _Static_assert(!__builtin_constant_p(!!sym), #sym " should be marked as __weak"); \ | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~ Fortunately recent versions of GCC support a __builtin_has_attribute that can be used to directly check for the __weak__ attribute. This patch changes bpf_helpers.h to use that builtin when building with a recent enough GCC, and to omit the check if GCC is too old to support the builtin. The macro used for GCC becomes: #define bpf_ksym_exists(sym) ({ \ _Static_assert(__builtin_has_attribute (*sym, __weak__), #sym " should be marked as __weak"); \ !!sym; \ }) Note that since bpf_ksym_exists is designed to get the address of the object associated with symbol SYM, we pass *sym to __builtin_has_attribute instead of sym. When an expression is passed to __builtin_has_attribute then it is the type of the passed expression that is checked for the specified attribute. The expression itself is not evaluated. This accommodates well with the existing usages of the macro: - For function objects: struct task_struct *bpf_task_acquire(struct task_struct *p) __ksym __weak; [...] bpf_ksym_exists(bpf_task_acquire) - For variable objects: extern const struct rq runqueues __ksym __weak; /* typed */ [...] bpf_ksym_exists(&runqueues) Note also that BPF support was added in GCC 10 and support for __builtin_has_attribute in GCC 9. Locally tested in bpf-next master branch. No regressions. Signed-of-by: Jose E. Marchesi Signed-off-by: Andrii Nakryiko Acked-by: Yonghong Song Link: https://lore.kernel.org/bpf/20240428112559.10518-1-jose.marchesi@oracle.com --- src/bpf_helpers.h | 17 ++++++++++++++--- 1 file changed, 14 insertions(+), 3 deletions(-) diff --git a/src/bpf_helpers.h b/src/bpf_helpers.h index 62e1c0c..305c628 100644 --- a/src/bpf_helpers.h +++ b/src/bpf_helpers.h @@ -186,10 +186,21 @@ enum libbpf_tristate { #define __kptr __attribute__((btf_type_tag("kptr"))) #define __percpu_kptr __attribute__((btf_type_tag("percpu_kptr"))) -#define bpf_ksym_exists(sym) ({ \ - _Static_assert(!__builtin_constant_p(!!sym), #sym " should be marked as __weak"); \ - !!sym; \ +#if defined (__clang__) +#define bpf_ksym_exists(sym) ({ \ + _Static_assert(!__builtin_constant_p(!!sym), \ + #sym " should be marked as __weak"); \ + !!sym; \ }) +#elif __GNUC__ > 8 +#define bpf_ksym_exists(sym) ({ \ + _Static_assert(__builtin_has_attribute (*sym, __weak__), \ + #sym " should be marked as __weak"); \ + !!sym; \ +}) +#else +#define bpf_ksym_exists(sym) !!sym +#endif #define __arg_ctx __attribute__((btf_decl_tag("arg:ctx"))) #define __arg_nonnull __attribute((btf_decl_tag("arg:nonnull"))) From ea02e10fc435d4afecaab262f19dc9fed5ab61ef Mon Sep 17 00:00:00 2001 From: "Jose E. Marchesi" Date: Thu, 2 May 2024 19:09:25 +0200 Subject: [PATCH 06/12] libbpf: Avoid casts from pointers to enums in bpf_tracing.h [Differences from V1: - Do not introduce a global typedef, as this is a public header. - Keep the void* casts in BPF_KPROBE_READ_RET_IP and BPF_KRETPROBE_READ_RET_IP, as these are necessary for converting to a const void* argument of bpf_probe_read_kernel.] The BPF_PROG, BPF_KPROBE and BPF_KSYSCALL macros defined in tools/lib/bpf/bpf_tracing.h use a clever hack in order to provide a convenient way to define entry points for BPF programs as if they were normal C functions that get typed actual arguments, instead of as elements in a single "context" array argument. For example, PPF_PROGS allows writing: SEC("struct_ops/cwnd_event") void BPF_PROG(cwnd_event, struct sock *sk, enum tcp_ca_event event) { bbr_cwnd_event(sk, event); dctcp_cwnd_event(sk, event); cubictcp_cwnd_event(sk, event); } That expands into a pair of functions: void ____cwnd_event (unsigned long long *ctx, struct sock *sk, enum tcp_ca_event event) { bbr_cwnd_event(sk, event); dctcp_cwnd_event(sk, event); cubictcp_cwnd_event(sk, event); } void cwnd_event (unsigned long long *ctx) { _Pragma("GCC diagnostic push") _Pragma("GCC diagnostic ignored \"-Wint-conversion\"") return ____cwnd_event(ctx, (void*)ctx[0], (void*)ctx[1]); _Pragma("GCC diagnostic pop") } Note how the 64-bit unsigned integers in the incoming CTX get casted to a void pointer, and then implicitly converted to whatever type of the actual argument in the wrapped function. In this case: Arg1: unsigned long long -> void * -> struct sock * Arg2: unsigned long long -> void * -> enum tcp_ca_event The behavior of GCC and clang when facing such conversions differ: pointer -> pointer Allowed by the C standard. GCC: no warning nor error. clang: no warning nor error. pointer -> integer type [C standard says the result of this conversion is implementation defined, and it may lead to unaligned pointer etc.] GCC: error: integer from pointer without a cast [-Wint-conversion] clang: error: incompatible pointer to integer conversion [-Wint-conversion] pointer -> enumerated type GCC: error: incompatible types in assigment (*) clang: error: incompatible pointer to integer conversion [-Wint-conversion] These macros work because converting pointers to pointers is allowed, and converting pointers to integers also works provided a suitable integer type even if it is implementation defined, much like casting a pointer to uintptr_t is guaranteed to work by the C standard. The conversion errors emitted by both compilers by default are silenced by the pragmas. However, the GCC error marked with (*) above when assigning a pointer to an enumerated value is not associated with the -Wint-conversion warning, and it is not possible to turn it off. This is preventing building the BPF kernel selftests with GCC. This patch fixes this by avoiding intermediate casts to void*, replaced with casts to `unsigned long long', which is an integer type capable of safely store a BPF pointer, much like the standard uintptr_t. Testing performed in bpf-next master: - vmtest.sh -- ./test_verifier - vmtest.sh -- ./test_progs - make M=samples/bpf No regressions. Signed-off-by: Jose E. Marchesi Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20240502170925.3194-1-jose.marchesi@oracle.com --- src/bpf_tracing.h | 70 +++++++++++++++++++++++------------------------ src/usdt.bpf.h | 24 ++++++++-------- 2 files changed, 47 insertions(+), 47 deletions(-) diff --git a/src/bpf_tracing.h b/src/bpf_tracing.h index 1c13f8e..9314fa9 100644 --- a/src/bpf_tracing.h +++ b/src/bpf_tracing.h @@ -633,18 +633,18 @@ struct pt_regs; #endif #define ___bpf_ctx_cast0() ctx -#define ___bpf_ctx_cast1(x) ___bpf_ctx_cast0(), (void *)ctx[0] -#define ___bpf_ctx_cast2(x, args...) ___bpf_ctx_cast1(args), (void *)ctx[1] -#define ___bpf_ctx_cast3(x, args...) ___bpf_ctx_cast2(args), (void *)ctx[2] -#define ___bpf_ctx_cast4(x, args...) ___bpf_ctx_cast3(args), (void *)ctx[3] -#define ___bpf_ctx_cast5(x, args...) ___bpf_ctx_cast4(args), (void *)ctx[4] -#define ___bpf_ctx_cast6(x, args...) ___bpf_ctx_cast5(args), (void *)ctx[5] -#define ___bpf_ctx_cast7(x, args...) ___bpf_ctx_cast6(args), (void *)ctx[6] -#define ___bpf_ctx_cast8(x, args...) ___bpf_ctx_cast7(args), (void *)ctx[7] -#define ___bpf_ctx_cast9(x, args...) ___bpf_ctx_cast8(args), (void *)ctx[8] -#define ___bpf_ctx_cast10(x, args...) ___bpf_ctx_cast9(args), (void *)ctx[9] -#define ___bpf_ctx_cast11(x, args...) ___bpf_ctx_cast10(args), (void *)ctx[10] -#define ___bpf_ctx_cast12(x, args...) ___bpf_ctx_cast11(args), (void *)ctx[11] +#define ___bpf_ctx_cast1(x) ___bpf_ctx_cast0(), ctx[0] +#define ___bpf_ctx_cast2(x, args...) ___bpf_ctx_cast1(args), ctx[1] +#define ___bpf_ctx_cast3(x, args...) ___bpf_ctx_cast2(args), ctx[2] +#define ___bpf_ctx_cast4(x, args...) ___bpf_ctx_cast3(args), ctx[3] +#define ___bpf_ctx_cast5(x, args...) ___bpf_ctx_cast4(args), ctx[4] +#define ___bpf_ctx_cast6(x, args...) ___bpf_ctx_cast5(args), ctx[5] +#define ___bpf_ctx_cast7(x, args...) ___bpf_ctx_cast6(args), ctx[6] +#define ___bpf_ctx_cast8(x, args...) ___bpf_ctx_cast7(args), ctx[7] +#define ___bpf_ctx_cast9(x, args...) ___bpf_ctx_cast8(args), ctx[8] +#define ___bpf_ctx_cast10(x, args...) ___bpf_ctx_cast9(args), ctx[9] +#define ___bpf_ctx_cast11(x, args...) ___bpf_ctx_cast10(args), ctx[10] +#define ___bpf_ctx_cast12(x, args...) ___bpf_ctx_cast11(args), ctx[11] #define ___bpf_ctx_cast(args...) ___bpf_apply(___bpf_ctx_cast, ___bpf_narg(args))(args) /* @@ -786,14 +786,14 @@ ____##name(unsigned long long *ctx ___bpf_ctx_decl(args)) struct pt_regs; #define ___bpf_kprobe_args0() ctx -#define ___bpf_kprobe_args1(x) ___bpf_kprobe_args0(), (void *)PT_REGS_PARM1(ctx) -#define ___bpf_kprobe_args2(x, args...) ___bpf_kprobe_args1(args), (void *)PT_REGS_PARM2(ctx) -#define ___bpf_kprobe_args3(x, args...) ___bpf_kprobe_args2(args), (void *)PT_REGS_PARM3(ctx) -#define ___bpf_kprobe_args4(x, args...) ___bpf_kprobe_args3(args), (void *)PT_REGS_PARM4(ctx) -#define ___bpf_kprobe_args5(x, args...) ___bpf_kprobe_args4(args), (void *)PT_REGS_PARM5(ctx) -#define ___bpf_kprobe_args6(x, args...) ___bpf_kprobe_args5(args), (void *)PT_REGS_PARM6(ctx) -#define ___bpf_kprobe_args7(x, args...) ___bpf_kprobe_args6(args), (void *)PT_REGS_PARM7(ctx) -#define ___bpf_kprobe_args8(x, args...) ___bpf_kprobe_args7(args), (void *)PT_REGS_PARM8(ctx) +#define ___bpf_kprobe_args1(x) ___bpf_kprobe_args0(), (unsigned long long)PT_REGS_PARM1(ctx) +#define ___bpf_kprobe_args2(x, args...) ___bpf_kprobe_args1(args), (unsigned long long)PT_REGS_PARM2(ctx) +#define ___bpf_kprobe_args3(x, args...) ___bpf_kprobe_args2(args), (unsigned long long)PT_REGS_PARM3(ctx) +#define ___bpf_kprobe_args4(x, args...) ___bpf_kprobe_args3(args), (unsigned long long)PT_REGS_PARM4(ctx) +#define ___bpf_kprobe_args5(x, args...) ___bpf_kprobe_args4(args), (unsigned long long)PT_REGS_PARM5(ctx) +#define ___bpf_kprobe_args6(x, args...) ___bpf_kprobe_args5(args), (unsigned long long)PT_REGS_PARM6(ctx) +#define ___bpf_kprobe_args7(x, args...) ___bpf_kprobe_args6(args), (unsigned long long)PT_REGS_PARM7(ctx) +#define ___bpf_kprobe_args8(x, args...) ___bpf_kprobe_args7(args), (unsigned long long)PT_REGS_PARM8(ctx) #define ___bpf_kprobe_args(args...) ___bpf_apply(___bpf_kprobe_args, ___bpf_narg(args))(args) /* @@ -821,7 +821,7 @@ static __always_inline typeof(name(0)) \ ____##name(struct pt_regs *ctx, ##args) #define ___bpf_kretprobe_args0() ctx -#define ___bpf_kretprobe_args1(x) ___bpf_kretprobe_args0(), (void *)PT_REGS_RC(ctx) +#define ___bpf_kretprobe_args1(x) ___bpf_kretprobe_args0(), (unsigned long long)PT_REGS_RC(ctx) #define ___bpf_kretprobe_args(args...) ___bpf_apply(___bpf_kretprobe_args, ___bpf_narg(args))(args) /* @@ -845,24 +845,24 @@ static __always_inline typeof(name(0)) ____##name(struct pt_regs *ctx, ##args) /* If kernel has CONFIG_ARCH_HAS_SYSCALL_WRAPPER, read pt_regs directly */ #define ___bpf_syscall_args0() ctx -#define ___bpf_syscall_args1(x) ___bpf_syscall_args0(), (void *)PT_REGS_PARM1_SYSCALL(regs) -#define ___bpf_syscall_args2(x, args...) ___bpf_syscall_args1(args), (void *)PT_REGS_PARM2_SYSCALL(regs) -#define ___bpf_syscall_args3(x, args...) ___bpf_syscall_args2(args), (void *)PT_REGS_PARM3_SYSCALL(regs) -#define ___bpf_syscall_args4(x, args...) ___bpf_syscall_args3(args), (void *)PT_REGS_PARM4_SYSCALL(regs) -#define ___bpf_syscall_args5(x, args...) ___bpf_syscall_args4(args), (void *)PT_REGS_PARM5_SYSCALL(regs) -#define ___bpf_syscall_args6(x, args...) ___bpf_syscall_args5(args), (void *)PT_REGS_PARM6_SYSCALL(regs) -#define ___bpf_syscall_args7(x, args...) ___bpf_syscall_args6(args), (void *)PT_REGS_PARM7_SYSCALL(regs) +#define ___bpf_syscall_args1(x) ___bpf_syscall_args0(), (unsigned long long)PT_REGS_PARM1_SYSCALL(regs) +#define ___bpf_syscall_args2(x, args...) ___bpf_syscall_args1(args), (unsigned long long)PT_REGS_PARM2_SYSCALL(regs) +#define ___bpf_syscall_args3(x, args...) ___bpf_syscall_args2(args), (unsigned long long)PT_REGS_PARM3_SYSCALL(regs) +#define ___bpf_syscall_args4(x, args...) ___bpf_syscall_args3(args), (unsigned long long)PT_REGS_PARM4_SYSCALL(regs) +#define ___bpf_syscall_args5(x, args...) ___bpf_syscall_args4(args), (unsigned long long)PT_REGS_PARM5_SYSCALL(regs) +#define ___bpf_syscall_args6(x, args...) ___bpf_syscall_args5(args), (unsigned long long)PT_REGS_PARM6_SYSCALL(regs) +#define ___bpf_syscall_args7(x, args...) ___bpf_syscall_args6(args), (unsigned long long)PT_REGS_PARM7_SYSCALL(regs) #define ___bpf_syscall_args(args...) ___bpf_apply(___bpf_syscall_args, ___bpf_narg(args))(args) /* If kernel doesn't have CONFIG_ARCH_HAS_SYSCALL_WRAPPER, we have to BPF_CORE_READ from pt_regs */ #define ___bpf_syswrap_args0() ctx -#define ___bpf_syswrap_args1(x) ___bpf_syswrap_args0(), (void *)PT_REGS_PARM1_CORE_SYSCALL(regs) -#define ___bpf_syswrap_args2(x, args...) ___bpf_syswrap_args1(args), (void *)PT_REGS_PARM2_CORE_SYSCALL(regs) -#define ___bpf_syswrap_args3(x, args...) ___bpf_syswrap_args2(args), (void *)PT_REGS_PARM3_CORE_SYSCALL(regs) -#define ___bpf_syswrap_args4(x, args...) ___bpf_syswrap_args3(args), (void *)PT_REGS_PARM4_CORE_SYSCALL(regs) -#define ___bpf_syswrap_args5(x, args...) ___bpf_syswrap_args4(args), (void *)PT_REGS_PARM5_CORE_SYSCALL(regs) -#define ___bpf_syswrap_args6(x, args...) ___bpf_syswrap_args5(args), (void *)PT_REGS_PARM6_CORE_SYSCALL(regs) -#define ___bpf_syswrap_args7(x, args...) ___bpf_syswrap_args6(args), (void *)PT_REGS_PARM7_CORE_SYSCALL(regs) +#define ___bpf_syswrap_args1(x) ___bpf_syswrap_args0(), (unsigned long long)PT_REGS_PARM1_CORE_SYSCALL(regs) +#define ___bpf_syswrap_args2(x, args...) ___bpf_syswrap_args1(args), (unsigned long long)PT_REGS_PARM2_CORE_SYSCALL(regs) +#define ___bpf_syswrap_args3(x, args...) ___bpf_syswrap_args2(args), (unsigned long long)PT_REGS_PARM3_CORE_SYSCALL(regs) +#define ___bpf_syswrap_args4(x, args...) ___bpf_syswrap_args3(args), (unsigned long long)PT_REGS_PARM4_CORE_SYSCALL(regs) +#define ___bpf_syswrap_args5(x, args...) ___bpf_syswrap_args4(args), (unsigned long long)PT_REGS_PARM5_CORE_SYSCALL(regs) +#define ___bpf_syswrap_args6(x, args...) ___bpf_syswrap_args5(args), (unsigned long long)PT_REGS_PARM6_CORE_SYSCALL(regs) +#define ___bpf_syswrap_args7(x, args...) ___bpf_syswrap_args6(args), (unsigned long long)PT_REGS_PARM7_CORE_SYSCALL(regs) #define ___bpf_syswrap_args(args...) ___bpf_apply(___bpf_syswrap_args, ___bpf_narg(args))(args) /* diff --git a/src/usdt.bpf.h b/src/usdt.bpf.h index f676330..76359bc 100644 --- a/src/usdt.bpf.h +++ b/src/usdt.bpf.h @@ -214,18 +214,18 @@ long bpf_usdt_cookie(struct pt_regs *ctx) /* we rely on ___bpf_apply() and ___bpf_narg() macros already defined in bpf_tracing.h */ #define ___bpf_usdt_args0() ctx -#define ___bpf_usdt_args1(x) ___bpf_usdt_args0(), ({ long _x; bpf_usdt_arg(ctx, 0, &_x); (void *)_x; }) -#define ___bpf_usdt_args2(x, args...) ___bpf_usdt_args1(args), ({ long _x; bpf_usdt_arg(ctx, 1, &_x); (void *)_x; }) -#define ___bpf_usdt_args3(x, args...) ___bpf_usdt_args2(args), ({ long _x; bpf_usdt_arg(ctx, 2, &_x); (void *)_x; }) -#define ___bpf_usdt_args4(x, args...) ___bpf_usdt_args3(args), ({ long _x; bpf_usdt_arg(ctx, 3, &_x); (void *)_x; }) -#define ___bpf_usdt_args5(x, args...) ___bpf_usdt_args4(args), ({ long _x; bpf_usdt_arg(ctx, 4, &_x); (void *)_x; }) -#define ___bpf_usdt_args6(x, args...) ___bpf_usdt_args5(args), ({ long _x; bpf_usdt_arg(ctx, 5, &_x); (void *)_x; }) -#define ___bpf_usdt_args7(x, args...) ___bpf_usdt_args6(args), ({ long _x; bpf_usdt_arg(ctx, 6, &_x); (void *)_x; }) -#define ___bpf_usdt_args8(x, args...) ___bpf_usdt_args7(args), ({ long _x; bpf_usdt_arg(ctx, 7, &_x); (void *)_x; }) -#define ___bpf_usdt_args9(x, args...) ___bpf_usdt_args8(args), ({ long _x; bpf_usdt_arg(ctx, 8, &_x); (void *)_x; }) -#define ___bpf_usdt_args10(x, args...) ___bpf_usdt_args9(args), ({ long _x; bpf_usdt_arg(ctx, 9, &_x); (void *)_x; }) -#define ___bpf_usdt_args11(x, args...) ___bpf_usdt_args10(args), ({ long _x; bpf_usdt_arg(ctx, 10, &_x); (void *)_x; }) -#define ___bpf_usdt_args12(x, args...) ___bpf_usdt_args11(args), ({ long _x; bpf_usdt_arg(ctx, 11, &_x); (void *)_x; }) +#define ___bpf_usdt_args1(x) ___bpf_usdt_args0(), ({ long _x; bpf_usdt_arg(ctx, 0, &_x); _x; }) +#define ___bpf_usdt_args2(x, args...) ___bpf_usdt_args1(args), ({ long _x; bpf_usdt_arg(ctx, 1, &_x); _x; }) +#define ___bpf_usdt_args3(x, args...) ___bpf_usdt_args2(args), ({ long _x; bpf_usdt_arg(ctx, 2, &_x); _x; }) +#define ___bpf_usdt_args4(x, args...) ___bpf_usdt_args3(args), ({ long _x; bpf_usdt_arg(ctx, 3, &_x); _x; }) +#define ___bpf_usdt_args5(x, args...) ___bpf_usdt_args4(args), ({ long _x; bpf_usdt_arg(ctx, 4, &_x); _x; }) +#define ___bpf_usdt_args6(x, args...) ___bpf_usdt_args5(args), ({ long _x; bpf_usdt_arg(ctx, 5, &_x); _x; }) +#define ___bpf_usdt_args7(x, args...) ___bpf_usdt_args6(args), ({ long _x; bpf_usdt_arg(ctx, 6, &_x); _x; }) +#define ___bpf_usdt_args8(x, args...) ___bpf_usdt_args7(args), ({ long _x; bpf_usdt_arg(ctx, 7, &_x); _x; }) +#define ___bpf_usdt_args9(x, args...) ___bpf_usdt_args8(args), ({ long _x; bpf_usdt_arg(ctx, 8, &_x); _x; }) +#define ___bpf_usdt_args10(x, args...) ___bpf_usdt_args9(args), ({ long _x; bpf_usdt_arg(ctx, 9, &_x); _x; }) +#define ___bpf_usdt_args11(x, args...) ___bpf_usdt_args10(args), ({ long _x; bpf_usdt_arg(ctx, 10, &_x); _x; }) +#define ___bpf_usdt_args12(x, args...) ___bpf_usdt_args11(args), ({ long _x; bpf_usdt_arg(ctx, 11, &_x); _x; }) #define ___bpf_usdt_args(args...) ___bpf_apply(___bpf_usdt_args, ___bpf_narg(args))(args) /* From 504369cba4b1a9fe3b277c20b1d8d177fec9781a Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Mon, 6 May 2024 17:13:29 -0700 Subject: [PATCH 07/12] libbpf: remove unnecessary struct_ops prog validity check libbpf ensures that BPF program references set in map->st_ops->progs[i] during open phase are always valid STRUCT_OPS programs. This is done in bpf_object__collect_st_ops_relos(). So there is no need to double-check that in bpf_map__init_kern_struct_ops(). Simplify the code by removing unnecessary check. Also, we avoid using local prog variable to keep code similar to the upcoming fix, which adds similar logic in another part of bpf_map__init_kern_struct_ops(). Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20240507001335.1445325-2-andrii@kernel.org Signed-off-by: Martin KaFai Lau --- src/libbpf.c | 13 +++---------- 1 file changed, 3 insertions(+), 10 deletions(-) diff --git a/src/libbpf.c b/src/libbpf.c index a3566a4..7d77a1b 100644 --- a/src/libbpf.c +++ b/src/libbpf.c @@ -1152,22 +1152,15 @@ static int bpf_map__init_kern_struct_ops(struct bpf_map *map) return -ENOTSUP; } - prog = st_ops->progs[i]; - if (prog) { + if (st_ops->progs[i]) { /* If we had declaratively set struct_ops callback, we need to - * first validate that it's actually a struct_ops program. - * And then force its autoload to false, because it doesn't have + * force its autoload to false, because it doesn't have * a chance of succeeding from POV of the current struct_ops map. * If this program is still referenced somewhere else, though, * then bpf_object_adjust_struct_ops_autoload() will update its * autoload accordingly. */ - if (!is_valid_st_ops_program(obj, prog)) { - pr_warn("struct_ops init_kern %s: member %s is declaratively assigned a non-struct_ops program\n", - map->name, mname); - return -EINVAL; - } - prog->autoload = false; + st_ops->progs[i]->autoload = false; st_ops->progs[i] = NULL; } From fe5fe762b90e33acb8f3528ac3742e6187389188 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Mon, 6 May 2024 17:13:30 -0700 Subject: [PATCH 08/12] libbpf: handle yet another corner case of nulling out struct_ops program There is yet another corner case where user can set STRUCT_OPS program reference in STRUCT_OPS map to NULL, but libbpf will fail to disable autoload for such BPF program. This time it's the case of "new" kernel which has type information about callback field, but user explicitly nulled-out program reference from user-space after opening BPF object. Fix, hopefully, the last remaining unhandled case. Fixes: 0737df6de946 ("libbpf: better fix for handling nulled-out struct_ops program") Fixes: f973fccd43d3 ("libbpf: handle nulled-out program in struct_ops correctly") Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20240507001335.1445325-3-andrii@kernel.org Signed-off-by: Martin KaFai Lau --- src/libbpf.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/src/libbpf.c b/src/libbpf.c index 7d77a1b..04de4fb 100644 --- a/src/libbpf.c +++ b/src/libbpf.c @@ -1193,11 +1193,19 @@ static int bpf_map__init_kern_struct_ops(struct bpf_map *map) } if (btf_is_ptr(mtype)) { - /* Update the value from the shadow type */ prog = *(void **)mdata; + /* just like for !kern_member case above, reset declaratively + * set (at compile time) program's autload to false, + * if user replaced it with another program or NULL + */ + if (st_ops->progs[i] && st_ops->progs[i] != prog) + st_ops->progs[i]->autoload = false; + + /* Update the value from the shadow type */ st_ops->progs[i] = prog; if (!prog) continue; + if (!is_valid_st_ops_program(obj, prog)) { pr_warn("struct_ops init_kern %s: member %s is not a struct_ops program\n", map->name, mname); From ed54f3030703947f741ad81a75bf98d379e37fe2 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Mon, 6 May 2024 17:13:32 -0700 Subject: [PATCH 09/12] libbpf: fix libbpf_strerror_r() handling unknown errors strerror_r(), used from libbpf-specific libbpf_strerror_r() wrapper is documented to return error in two different ways, depending on glibc version. Take that into account when handling strerror_r()'s own errors, which happens when we pass some non-standard (internal) kernel error to it. Before this patch we'd have "ERROR: strerror_r(524)=22", which is quite confusing. Now for the same situation we'll see a bit less visually scary "unknown error (-524)". At least we won't confuse user with irrelevant EINVAL (22). Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20240507001335.1445325-5-andrii@kernel.org Signed-off-by: Martin KaFai Lau --- src/str_error.c | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-) diff --git a/src/str_error.c b/src/str_error.c index 146da01..5e6a1e2 100644 --- a/src/str_error.c +++ b/src/str_error.c @@ -2,6 +2,7 @@ #undef _GNU_SOURCE #include #include +#include #include "str_error.h" /* make sure libbpf doesn't use kernel-only integer typedefs */ @@ -15,7 +16,18 @@ char *libbpf_strerror_r(int err, char *dst, int len) { int ret = strerror_r(err < 0 ? -err : err, dst, len); - if (ret) - snprintf(dst, len, "ERROR: strerror_r(%d)=%d", err, ret); + /* on glibc <2.13, ret == -1 and errno is set, if strerror_r() can't + * handle the error, on glibc >=2.13 *positive* (errno-like) error + * code is returned directly + */ + if (ret == -1) + ret = errno; + if (ret) { + if (ret == EINVAL) + /* strerror_r() doesn't recognize this specific error */ + snprintf(dst, len, "unknown error (%d)", err < 0 ? err : -err); + else + snprintf(dst, len, "ERROR: strerror_r(%d)=%d", err, ret); + } return dst; } From e5146eff759a8bdce65c4391e6ba321d3dec0107 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Mon, 6 May 2024 17:13:33 -0700 Subject: [PATCH 10/12] libbpf: improve early detection of doomed-to-fail BPF program loading Extend libbpf's pre-load checks for BPF programs, detecting more typical conditions that are destinated to cause BPF program failure. This is an opportunity to provide more helpful and actionable error message to users, instead of potentially very confusing BPF verifier log and/or error. In this case, we detect struct_ops BPF program that was not referenced anywhere, but still attempted to be loaded (according to libbpf logic). Suggest that the program might need to be used in some struct_ops variable. User will get a message of the following kind: libbpf: prog 'test_1_forgotten': SEC("struct_ops") program isn't referenced anywhere, did you forget to use it? Suggested-by: Tejun Heo Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20240507001335.1445325-6-andrii@kernel.org Signed-off-by: Martin KaFai Lau --- src/libbpf.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/src/libbpf.c b/src/libbpf.c index 04de4fb..5401f2d 100644 --- a/src/libbpf.c +++ b/src/libbpf.c @@ -7372,7 +7372,11 @@ static int bpf_object_load_prog(struct bpf_object *obj, struct bpf_program *prog __u32 log_level = prog->log_level; int ret, err; - if (prog->type == BPF_PROG_TYPE_UNSPEC) { + /* Be more helpful by rejecting programs that can't be validated early + * with more meaningful and actionable error message. + */ + switch (prog->type) { + case BPF_PROG_TYPE_UNSPEC: /* * The program type must be set. Most likely we couldn't find a proper * section definition at load time, and thus we didn't infer the type. @@ -7380,6 +7384,15 @@ static int bpf_object_load_prog(struct bpf_object *obj, struct bpf_program *prog pr_warn("prog '%s': missing BPF prog type, check ELF section name '%s'\n", prog->name, prog->sec_name); return -EINVAL; + case BPF_PROG_TYPE_STRUCT_OPS: + if (prog->attach_btf_id == 0) { + pr_warn("prog '%s': SEC(\"struct_ops\") program isn't referenced anywhere, did you forget to use it?\n", + prog->name); + return -EINVAL; + } + break; + default: + break; } if (!insns || !insns_cnt) From 3827aa514cba7db16b81236712a46e8b70260fcd Mon Sep 17 00:00:00 2001 From: "Jose E. Marchesi" Date: Wed, 8 May 2024 12:13:13 +0200 Subject: [PATCH 11/12] bpf: Avoid uninitialized value in BPF_CORE_READ_BITFIELD [Changes from V1: - Use a default branch in the switch statement to initialize `val'.] GCC warns that `val' may be used uninitialized in the BPF_CRE_READ_BITFIELD macro, defined in bpf_core_read.h as: [...] unsigned long long val; \ [...] \ switch (__CORE_RELO(s, field, BYTE_SIZE)) { \ case 1: val = *(const unsigned char *)p; break; \ case 2: val = *(const unsigned short *)p; break; \ case 4: val = *(const unsigned int *)p; break; \ case 8: val = *(const unsigned long long *)p; break; \ } \ [...] val; \ } \ This patch adds a default entry in the switch statement that sets `val' to zero in order to avoid the warning, and random values to be used in case __builtin_preserve_field_info returns unexpected values for BPF_FIELD_BYTE_SIZE. Tested in bpf-next master. No regressions. Signed-off-by: Jose E. Marchesi Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20240508101313.16662-1-jose.marchesi@oracle.com --- src/bpf_core_read.h | 1 + 1 file changed, 1 insertion(+) diff --git a/src/bpf_core_read.h b/src/bpf_core_read.h index b5c7ce5..c0e13cd 100644 --- a/src/bpf_core_read.h +++ b/src/bpf_core_read.h @@ -104,6 +104,7 @@ enum bpf_enum_value_kind { case 2: val = *(const unsigned short *)p; break; \ case 4: val = *(const unsigned int *)p; break; \ case 8: val = *(const unsigned long long *)p; break; \ + default: val = 0; break; \ } \ val <<= __CORE_RELO(s, field, LSHIFT_U64); \ if (__CORE_RELO(s, field, SIGNED)) \ From 02724cfd0702c4102138e62c3ae7d2721c7b190e Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Wed, 8 May 2024 15:23:40 -0700 Subject: [PATCH 12/12] sync: latest libbpf changes from kernel Syncing latest libbpf commits from kernel repository. Baseline bpf-next commit: 0737df6de94661ae55fd3343ce9abec32c687e62 Checkpoint bpf-next commit: 009367099eb61a4fc2af44d4eb06b6b4de7de6db Baseline bpf commit: 3e9bc0472b910d4115e16e9c2d684c7757cb6c60 Checkpoint bpf commit: 3e9bc0472b910d4115e16e9c2d684c7757cb6c60 Andrii Nakryiko (6): libbpf: fix potential overflow in ring__consume_n() libbpf: fix ring_buffer__consume_n() return result logic libbpf: remove unnecessary struct_ops prog validity check libbpf: handle yet another corner case of nulling out struct_ops program libbpf: fix libbpf_strerror_r() handling unknown errors libbpf: improve early detection of doomed-to-fail BPF program loading Jiri Olsa (2): libbpf: Fix error message in attach_kprobe_session libbpf: Fix error message in attach_kprobe_multi Jose E. Marchesi (3): libbpf: Fix bpf_ksym_exists() in GCC libbpf: Avoid casts from pointers to enums in bpf_tracing.h bpf: Avoid uninitialized value in BPF_CORE_READ_BITFIELD src/bpf_core_read.h | 1 + src/bpf_helpers.h | 17 +++++++++-- src/bpf_tracing.h | 70 ++++++++++++++++++++++----------------------- src/libbpf.c | 42 ++++++++++++++++++--------- src/ringbuf.c | 4 +-- src/str_error.c | 16 +++++++++-- src/usdt.bpf.h | 24 ++++++++-------- 7 files changed, 106 insertions(+), 68 deletions(-) Signed-off-by: Andrii Nakryiko --- CHECKPOINT-COMMIT | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/CHECKPOINT-COMMIT b/CHECKPOINT-COMMIT index 56ad654..0e3fb52 100644 --- a/CHECKPOINT-COMMIT +++ b/CHECKPOINT-COMMIT @@ -1 +1 @@ -0737df6de94661ae55fd3343ce9abec32c687e62 +009367099eb61a4fc2af44d4eb06b6b4de7de6db