From 6298399bfc101f8e8cf35a916f26aa32bdf04278 Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Tue, 25 Aug 2020 21:21:13 +0200 Subject: bpf: Move btf_resolve_size into __btf_resolve_size Moving btf_resolve_size into __btf_resolve_size and keeping btf_resolve_size public with just first 3 arguments, because the rest of the arguments are not used by outside callers. Following changes are adding more arguments, which are not useful to outside callers. They will be added to the __btf_resolve_size function. Signed-off-by: Jiri Olsa Signed-off-by: Alexei Starovoitov Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20200825192124.710397-4-jolsa@kernel.org --- include/linux/btf.h | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) (limited to 'include/linux/btf.h') diff --git a/include/linux/btf.h b/include/linux/btf.h index 8b81fbb4497c..a9af5e7a7ece 100644 --- a/include/linux/btf.h +++ b/include/linux/btf.h @@ -64,8 +64,7 @@ const struct btf_type *btf_type_resolve_func_ptr(const struct btf *btf, u32 id, u32 *res_id); const struct btf_type * btf_resolve_size(const struct btf *btf, const struct btf_type *type, - u32 *type_size, const struct btf_type **elem_type, - u32 *total_nelems); + u32 *type_size); #define for_each_member(i, struct_type, member) \ for (i = 0, member = btf_type_member(struct_type); \ -- cgit v1.2.3 From 31d0bc81637d8d974a6dad9827b765b4b70c89d7 Mon Sep 17 00:00:00 2001 From: Alan Maguire Date: Mon, 28 Sep 2020 12:31:04 +0100 Subject: bpf: Move to generic BTF show support, apply it to seq files/strings generalize the "seq_show" seq file support in btf.c to support a generic show callback of which we support two instances; the current seq file show, and a show with snprintf() behaviour which instead writes the type data to a supplied string. Both classes of show function call btf_type_show() with different targets; the seq file or the string to be written. In the string case we need to track additional data - length left in string to write and length to return that we would have written (a la snprintf). By default show will display type information, field members and their types and values etc, and the information is indented based upon structure depth. Zeroed fields are omitted. Show however supports flags which modify its behaviour: BTF_SHOW_COMPACT - suppress newline/indent. BTF_SHOW_NONAME - suppress show of type and member names. BTF_SHOW_PTR_RAW - do not obfuscate pointer values. BTF_SHOW_UNSAFE - do not copy data to safe buffer before display. BTF_SHOW_ZERO - show zeroed values (by default they are not shown). Signed-off-by: Alan Maguire Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/1601292670-1616-3-git-send-email-alan.maguire@oracle.com --- include/linux/btf.h | 36 ++++++++++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+) (limited to 'include/linux/btf.h') diff --git a/include/linux/btf.h b/include/linux/btf.h index a9af5e7a7ece..d0f5d3c9ec3d 100644 --- a/include/linux/btf.h +++ b/include/linux/btf.h @@ -13,6 +13,7 @@ struct btf; struct btf_member; struct btf_type; union bpf_attr; +struct btf_show; extern const struct file_operations btf_fops; @@ -46,8 +47,43 @@ int btf_get_info_by_fd(const struct btf *btf, const struct btf_type *btf_type_id_size(const struct btf *btf, u32 *type_id, u32 *ret_size); + +/* + * Options to control show behaviour. + * - BTF_SHOW_COMPACT: no formatting around type information + * - BTF_SHOW_NONAME: no struct/union member names/types + * - BTF_SHOW_PTR_RAW: show raw (unobfuscated) pointer values; + * equivalent to %px. + * - BTF_SHOW_ZERO: show zero-valued struct/union members; they + * are not displayed by default + * - BTF_SHOW_UNSAFE: skip use of bpf_probe_read() to safely read + * data before displaying it. + */ +#define BTF_SHOW_COMPACT (1ULL << 0) +#define BTF_SHOW_NONAME (1ULL << 1) +#define BTF_SHOW_PTR_RAW (1ULL << 2) +#define BTF_SHOW_ZERO (1ULL << 3) +#define BTF_SHOW_UNSAFE (1ULL << 4) + void btf_type_seq_show(const struct btf *btf, u32 type_id, void *obj, struct seq_file *m); + +/* + * Copy len bytes of string representation of obj of BTF type_id into buf. + * + * @btf: struct btf object + * @type_id: type id of type obj points to + * @obj: pointer to typed data + * @buf: buffer to write to + * @len: maximum length to write to buf + * @flags: show options (see above) + * + * Return: length that would have been/was copied as per snprintf, or + * negative error. + */ +int btf_type_snprintf_show(const struct btf *btf, u32 type_id, void *obj, + char *buf, int len, u64 flags); + int btf_get_fd_by_id(u32 id); u32 btf_id(const struct btf *btf); bool btf_member_is_reg_int(const struct btf *btf, const struct btf_type *s, -- cgit v1.2.3 From c4d0bfb45068d853a478b9067a95969b1886a30f Mon Sep 17 00:00:00 2001 From: Alan Maguire Date: Mon, 28 Sep 2020 12:31:05 +0100 Subject: bpf: Add bpf_snprintf_btf helper A helper is added to support tracing kernel type information in BPF using the BPF Type Format (BTF). Its signature is long bpf_snprintf_btf(char *str, u32 str_size, struct btf_ptr *ptr, u32 btf_ptr_size, u64 flags); struct btf_ptr * specifies - a pointer to the data to be traced - the BTF id of the type of data pointed to - a flags field is provided for future use; these flags are not to be confused with the BTF_F_* flags below that control how the btf_ptr is displayed; the flags member of the struct btf_ptr may be used to disambiguate types in kernel versus module BTF, etc; the main distinction is the flags relate to the type and information needed in identifying it; not how it is displayed. For example a BPF program with a struct sk_buff *skb could do the following: static struct btf_ptr b = { }; b.ptr = skb; b.type_id = __builtin_btf_type_id(struct sk_buff, 1); bpf_snprintf_btf(str, sizeof(str), &b, sizeof(b), 0, 0); Default output looks like this: (struct sk_buff){ .transport_header = (__u16)65535, .mac_header = (__u16)65535, .end = (sk_buff_data_t)192, .head = (unsigned char *)0x000000007524fd8b, .data = (unsigned char *)0x000000007524fd8b, .truesize = (unsigned int)768, .users = (refcount_t){ .refs = (atomic_t){ .counter = (int)1, }, }, } Flags modifying display are as follows: - BTF_F_COMPACT: no formatting around type information - BTF_F_NONAME: no struct/union member names/types - BTF_F_PTR_RAW: show raw (unobfuscated) pointer values; equivalent to %px. - BTF_F_ZERO: show zero-valued struct/union members; they are not displayed by default Signed-off-by: Alan Maguire Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/1601292670-1616-4-git-send-email-alan.maguire@oracle.com --- include/linux/btf.h | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) (limited to 'include/linux/btf.h') diff --git a/include/linux/btf.h b/include/linux/btf.h index d0f5d3c9ec3d..3e5cdc2ba963 100644 --- a/include/linux/btf.h +++ b/include/linux/btf.h @@ -6,6 +6,7 @@ #include #include +#include #define BTF_TYPE_EMIT(type) ((void)(type *)0) @@ -59,10 +60,10 @@ const struct btf_type *btf_type_id_size(const struct btf *btf, * - BTF_SHOW_UNSAFE: skip use of bpf_probe_read() to safely read * data before displaying it. */ -#define BTF_SHOW_COMPACT (1ULL << 0) -#define BTF_SHOW_NONAME (1ULL << 1) -#define BTF_SHOW_PTR_RAW (1ULL << 2) -#define BTF_SHOW_ZERO (1ULL << 3) +#define BTF_SHOW_COMPACT BTF_F_COMPACT +#define BTF_SHOW_NONAME BTF_F_NONAME +#define BTF_SHOW_PTR_RAW BTF_F_PTR_RAW +#define BTF_SHOW_ZERO BTF_F_ZERO #define BTF_SHOW_UNSAFE (1ULL << 4) void btf_type_seq_show(const struct btf *btf, u32 type_id, void *obj, -- cgit v1.2.3 From eb411377aed9e27835e77ee0710ee8f4649958f3 Mon Sep 17 00:00:00 2001 From: Alan Maguire Date: Mon, 28 Sep 2020 12:31:09 +0100 Subject: bpf: Add bpf_seq_printf_btf helper A helper is added to allow seq file writing of kernel data structures using vmlinux BTF. Its signature is long bpf_seq_printf_btf(struct seq_file *m, struct btf_ptr *ptr, u32 btf_ptr_size, u64 flags); Flags and struct btf_ptr definitions/use are identical to the bpf_snprintf_btf helper, and the helper returns 0 on success or a negative error value. Suggested-by: Alexei Starovoitov Signed-off-by: Alan Maguire Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/1601292670-1616-8-git-send-email-alan.maguire@oracle.com --- include/linux/btf.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include/linux/btf.h') diff --git a/include/linux/btf.h b/include/linux/btf.h index 3e5cdc2ba963..024e16ff7dcc 100644 --- a/include/linux/btf.h +++ b/include/linux/btf.h @@ -68,6 +68,8 @@ const struct btf_type *btf_type_id_size(const struct btf *btf, void btf_type_seq_show(const struct btf *btf, u32 type_id, void *obj, struct seq_file *m); +int btf_type_seq_show_flags(const struct btf *btf, u32 type_id, void *obj, + struct seq_file *m, u64 flags); /* * Copy len bytes of string representation of obj of BTF type_id into buf. -- cgit v1.2.3 From 4976b718c3551faba2c0616ef55ebeb74db1c5ca Mon Sep 17 00:00:00 2001 From: Hao Luo Date: Tue, 29 Sep 2020 16:50:44 -0700 Subject: bpf: Introduce pseudo_btf_id Pseudo_btf_id is a type of ld_imm insn that associates a btf_id to a ksym so that further dereferences on the ksym can use the BTF info to validate accesses. Internally, when seeing a pseudo_btf_id ld insn, the verifier reads the btf_id stored in the insn[0]'s imm field and marks the dst_reg as PTR_TO_BTF_ID. The btf_id points to a VAR_KIND, which is encoded in btf_vminux by pahole. If the VAR is not of a struct type, the dst reg will be marked as PTR_TO_MEM instead of PTR_TO_BTF_ID and the mem_size is resolved to the size of the VAR's type. >From the VAR btf_id, the verifier can also read the address of the ksym's corresponding kernel var from kallsyms and use that to fill dst_reg. Therefore, the proper functionality of pseudo_btf_id depends on (1) kallsyms and (2) the encoding of kernel global VARs in pahole, which should be available since pahole v1.18. Signed-off-by: Hao Luo Signed-off-by: Alexei Starovoitov Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20200929235049.2533242-2-haoluo@google.com --- include/linux/btf.h | 15 +++++++++++++++ 1 file changed, 15 insertions(+) (limited to 'include/linux/btf.h') diff --git a/include/linux/btf.h b/include/linux/btf.h index 024e16ff7dcc..af1244180588 100644 --- a/include/linux/btf.h +++ b/include/linux/btf.h @@ -145,6 +145,21 @@ static inline bool btf_type_is_func_proto(const struct btf_type *t) return BTF_INFO_KIND(t->info) == BTF_KIND_FUNC_PROTO; } +static inline bool btf_type_is_var(const struct btf_type *t) +{ + return BTF_INFO_KIND(t->info) == BTF_KIND_VAR; +} + +/* union is only a special case of struct: + * all its offsetof(member) == 0 + */ +static inline bool btf_type_is_struct(const struct btf_type *t) +{ + u8 kind = BTF_INFO_KIND(t->info); + + return kind == BTF_KIND_STRUCT || kind == BTF_KIND_UNION; +} + static inline u16 btf_type_vlen(const struct btf_type *t) { return BTF_INFO_VLEN(t->info); -- cgit v1.2.3 From eaa6bcb71ef6ed3dc18fc525ee7e293b06b4882b Mon Sep 17 00:00:00 2001 From: Hao Luo Date: Tue, 29 Sep 2020 16:50:47 -0700 Subject: bpf: Introduce bpf_per_cpu_ptr() Add bpf_per_cpu_ptr() to help bpf programs access percpu vars. bpf_per_cpu_ptr() has the same semantic as per_cpu_ptr() in the kernel except that it may return NULL. This happens when the cpu parameter is out of range. So the caller must check the returned value. Signed-off-by: Hao Luo Signed-off-by: Alexei Starovoitov Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20200929235049.2533242-5-haoluo@google.com --- include/linux/btf.h | 11 +++++++++++ 1 file changed, 11 insertions(+) (limited to 'include/linux/btf.h') diff --git a/include/linux/btf.h b/include/linux/btf.h index af1244180588..2bf641829664 100644 --- a/include/linux/btf.h +++ b/include/linux/btf.h @@ -110,6 +110,11 @@ btf_resolve_size(const struct btf *btf, const struct btf_type *type, i < btf_type_vlen(struct_type); \ i++, member++) +#define for_each_vsi(i, datasec_type, member) \ + for (i = 0, member = btf_type_var_secinfo(datasec_type); \ + i < btf_type_vlen(datasec_type); \ + i++, member++) + static inline bool btf_type_is_ptr(const struct btf_type *t) { return BTF_INFO_KIND(t->info) == BTF_KIND_PTR; @@ -194,6 +199,12 @@ static inline const struct btf_member *btf_type_member(const struct btf_type *t) return (const struct btf_member *)(t + 1); } +static inline const struct btf_var_secinfo *btf_type_var_secinfo( + const struct btf_type *t) +{ + return (const struct btf_var_secinfo *)(t + 1); +} + #ifdef CONFIG_BPF_SYSCALL const struct btf_type *btf_type_by_id(const struct btf *btf, u32 type_id); const char *btf_name_by_offset(const struct btf *btf, u32 offset); -- cgit v1.2.3