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libbpf: Minor style improvements in USDT code

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Fix several typos and references to non-existing headers.
Also use __BYTE_ORDER__ instead of __BYTE_ORDER for consistency with
the rest of the bpf code - see commit 45f2bebc8079 ("libbpf: Fix
endianness detection in BPF_CORE_READ_BITFIELD_PROBED()") for
rationale).

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220407214411.257260-2-iii@linux.ibm.com
This commit is contained in:
Ilya Leoshkevich
2022-04-07 23:44:09 +02:00
committed by Andrii Nakryiko
parent 73b8386f2e
commit fcb67a3e70
2 changed files with 8 additions and 8 deletions
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4
src/usdt.bpf.h
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@@ -166,7 +166,7 @@ int bpf_usdt_arg(struct pt_regs *ctx, __u64 arg_num, long *res)
case BPF_USDT_ARG_REG_DEREF: case BPF_USDT_ARG_REG_DEREF:
/* Arg is in memory addressed by register, plus some offset /* Arg is in memory addressed by register, plus some offset
* (e.g., "-4@-1204(%rbp)" in USDT arg spec). Register is * (e.g., "-4@-1204(%rbp)" in USDT arg spec). Register is
* identified lik with BPF_USDT_ARG_REG case, and the offset * identified like with BPF_USDT_ARG_REG case, and the offset
* is in arg_spec->val_off. We first fetch register contents * is in arg_spec->val_off. We first fetch register contents
* from pt_regs, then do another user-space probe read to * from pt_regs, then do another user-space probe read to
* fetch argument value itself. * fetch argument value itself.
@@ -198,7 +198,7 @@ int bpf_usdt_arg(struct pt_regs *ctx, __u64 arg_num, long *res)
/* Retrieve user-specified cookie value provided during attach as /* Retrieve user-specified cookie value provided during attach as
* bpf_usdt_opts.usdt_cookie. This serves the same purpose as BPF cookie * bpf_usdt_opts.usdt_cookie. This serves the same purpose as BPF cookie
* returned by bpf_get_attach_cookie(). Libbpf's support for USDT is itself * returned by bpf_get_attach_cookie(). Libbpf's support for USDT is itself
* utilizaing BPF cookies internally, so user can't use BPF cookie directly * utilizing BPF cookies internally, so user can't use BPF cookie directly
* for USDT programs and has to use bpf_usdt_cookie() API instead. * for USDT programs and has to use bpf_usdt_cookie() API instead.
*/ */
static inline __noinline static inline __noinline

12
src/usdt.c
View File

@@ -108,7 +108,7 @@
* code through spec map. This allows BPF applications to quickly fetch the * code through spec map. This allows BPF applications to quickly fetch the
* actual value at runtime using a simple BPF-side code. * actual value at runtime using a simple BPF-side code.
* *
* With basics out of the way, let's go over less immeditately obvious aspects * With basics out of the way, let's go over less immediately obvious aspects
* of supporting USDTs. * of supporting USDTs.
* *
* First, there is no special USDT BPF program type. It is actually just * First, there is no special USDT BPF program type. It is actually just
@@ -189,14 +189,14 @@
#define USDT_NOTE_TYPE 3 #define USDT_NOTE_TYPE 3
#define USDT_NOTE_NAME "stapsdt" #define USDT_NOTE_NAME "stapsdt"
/* should match exactly enum __bpf_usdt_arg_type from bpf_usdt.bpf.h */ /* should match exactly enum __bpf_usdt_arg_type from usdt.bpf.h */
enum usdt_arg_type { enum usdt_arg_type {
USDT_ARG_CONST, USDT_ARG_CONST,
USDT_ARG_REG, USDT_ARG_REG,
USDT_ARG_REG_DEREF, USDT_ARG_REG_DEREF,
}; };
/* should match exactly struct __bpf_usdt_arg_spec from bpf_usdt.bpf.h */ /* should match exactly struct __bpf_usdt_arg_spec from usdt.bpf.h */
struct usdt_arg_spec { struct usdt_arg_spec {
__u64 val_off; __u64 val_off;
enum usdt_arg_type arg_type; enum usdt_arg_type arg_type;
@@ -328,9 +328,9 @@ static int sanity_check_usdt_elf(Elf *elf, const char *path)
return -EBADF; return -EBADF;
} }
#if __BYTE_ORDER == __LITTLE_ENDIAN #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
endianness = ELFDATA2LSB; endianness = ELFDATA2LSB;
#elif __BYTE_ORDER == __BIG_ENDIAN #elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
endianness = ELFDATA2MSB; endianness = ELFDATA2MSB;
#else #else
# error "Unrecognized __BYTE_ORDER__" # error "Unrecognized __BYTE_ORDER__"
@@ -843,7 +843,7 @@ static int bpf_link_usdt_detach(struct bpf_link *link)
sizeof(*new_free_ids)); sizeof(*new_free_ids));
/* If we couldn't resize free_spec_ids, we'll just leak /* If we couldn't resize free_spec_ids, we'll just leak
* a bunch of free IDs; this is very unlikely to happen and if * a bunch of free IDs; this is very unlikely to happen and if
* system is so exausted on memory, it's the least of user's * system is so exhausted on memory, it's the least of user's
* concerns, probably. * concerns, probably.
* So just do our best here to return those IDs to usdt_manager. * So just do our best here to return those IDs to usdt_manager.
*/ */