Commit e1b6df59 authored by Ilya Leoshkevich's avatar Ilya Leoshkevich Committed by Andrii Nakryiko
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libbpf: Minor style improvements in USDT code 



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 45f2bebc ("libbpf: Fix
endianness detection in BPF_CORE_READ_BITFIELD_PROBED()") for
rationale).

Signed-off-by: default avatarIlya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220407214411.257260-2-iii@linux.ibm.com
parent ded6dffa

tools/lib/bpf/usdt.bpf.h

+2 −2
Original line number Diff line number Diff line
@@ -166,7 +166,7 @@ int bpf_usdt_arg(struct pt_regs *ctx, __u64 arg_num, long *res) 
	case BPF_USDT_ARG_REG_DEREF:

		/* Arg is in memory addressed by register, plus some offset

		 * (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

		 * from pt_regs, then do another user-space probe read to

		 * 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

 * 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

 * 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.

 */

static inline __noinline

tools/lib/bpf/usdt.c

+6 −6
Original line number Diff line number Diff line
@@ -108,7 +108,7 @@ 
 * code through spec map. This allows BPF applications to quickly fetch the

 * 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.

 *

 * 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_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 {

	USDT_ARG_CONST,

	USDT_ARG_REG,

	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 {

	__u64 val_off;

	enum usdt_arg_type arg_type;
@@ -328,9 +328,9 @@ static int sanity_check_usdt_elf(Elf *elf, const char *path) 
		return -EBADF;

	}



#if __BYTE_ORDER == __LITTLE_ENDIAN

#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__

	endianness = ELFDATA2LSB;

#elif __BYTE_ORDER == __BIG_ENDIAN

#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__

	endianness = ELFDATA2MSB;

#else

# error "Unrecognized __BYTE_ORDER__"
@@ -843,7 +843,7 @@ static int bpf_link_usdt_detach(struct bpf_link *link) 
						   sizeof(*new_free_ids));

		/* 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

		 * 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.

		 * So just do our best here to return those IDs to usdt_manager.

		 */