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Diffstat (limited to 'tools/lib/bpf/usdt.bpf.h')
-rw-r--r--tools/lib/bpf/usdt.bpf.h111
1 files changed, 93 insertions, 18 deletions
diff --git a/tools/lib/bpf/usdt.bpf.h b/tools/lib/bpf/usdt.bpf.h
index fdfd235e52c4..43deb05a5197 100644
--- a/tools/lib/bpf/usdt.bpf.h
+++ b/tools/lib/bpf/usdt.bpf.h
@@ -4,8 +4,8 @@
#define __USDT_BPF_H__
#include <linux/errno.h>
-#include <bpf/bpf_helpers.h>
-#include <bpf/bpf_tracing.h>
+#include "bpf_helpers.h"
+#include "bpf_tracing.h"
/* Below types and maps are internal implementation details of libbpf's USDT
* support and are subjects to change. Also, bpf_usdt_xxx() API helpers should
@@ -34,13 +34,32 @@ enum __bpf_usdt_arg_type {
BPF_USDT_ARG_CONST,
BPF_USDT_ARG_REG,
BPF_USDT_ARG_REG_DEREF,
+ BPF_USDT_ARG_SIB,
};
+/*
+ * This struct layout is designed specifically to be backwards/forward
+ * compatible between libbpf versions for ARG_CONST, ARG_REG, and
+ * ARG_REG_DEREF modes. ARG_SIB requires libbpf v1.7+.
+ */
struct __bpf_usdt_arg_spec {
/* u64 scalar interpreted depending on arg_type, see below */
__u64 val_off;
- /* arg location case, see bpf_udst_arg() for details */
- enum __bpf_usdt_arg_type arg_type;
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+ /* arg location case, see bpf_usdt_arg() for details */
+ enum __bpf_usdt_arg_type arg_type: 8;
+ /* index register offset within struct pt_regs */
+ __u16 idx_reg_off: 12;
+ /* scale factor for index register (1, 2, 4, or 8) */
+ __u16 scale_bitshift: 4;
+ /* reserved for future use, keeps reg_off offset stable */
+ __u8 __reserved: 8;
+#else
+ __u8 __reserved: 8;
+ __u16 idx_reg_off: 12;
+ __u16 scale_bitshift: 4;
+ enum __bpf_usdt_arg_type arg_type: 8;
+#endif
/* offset of referenced register within struct pt_regs */
short reg_off;
/* whether arg should be interpreted as signed value */
@@ -108,6 +127,38 @@ int bpf_usdt_arg_cnt(struct pt_regs *ctx)
return spec->arg_cnt;
}
+/* Returns the size in bytes of the #*arg_num* (zero-indexed) USDT argument.
+ * Returns negative error if argument is not found or arg_num is invalid.
+ */
+static __always_inline
+int bpf_usdt_arg_size(struct pt_regs *ctx, __u64 arg_num)
+{
+ struct __bpf_usdt_arg_spec *arg_spec;
+ struct __bpf_usdt_spec *spec;
+ int spec_id;
+
+ spec_id = __bpf_usdt_spec_id(ctx);
+ if (spec_id < 0)
+ return -ESRCH;
+
+ spec = bpf_map_lookup_elem(&__bpf_usdt_specs, &spec_id);
+ if (!spec)
+ return -ESRCH;
+
+ if (arg_num >= BPF_USDT_MAX_ARG_CNT)
+ return -ENOENT;
+ barrier_var(arg_num);
+ if (arg_num >= spec->arg_cnt)
+ return -ENOENT;
+
+ arg_spec = &spec->args[arg_num];
+
+ /* arg_spec->arg_bitshift = 64 - arg_sz * 8
+ * so: arg_sz = (64 - arg_spec->arg_bitshift) / 8
+ */
+ return (unsigned int)(64 - arg_spec->arg_bitshift) / 8;
+}
+
/* Fetch USDT argument #*arg_num* (zero-indexed) and put its value into *res.
* Returns 0 on success; negative error, otherwise.
* On error *res is guaranteed to be set to zero.
@@ -117,7 +168,7 @@ int bpf_usdt_arg(struct pt_regs *ctx, __u64 arg_num, long *res)
{
struct __bpf_usdt_spec *spec;
struct __bpf_usdt_arg_spec *arg_spec;
- unsigned long val;
+ unsigned long val, idx;
int err, spec_id;
*res = 0;
@@ -130,7 +181,10 @@ int bpf_usdt_arg(struct pt_regs *ctx, __u64 arg_num, long *res)
if (!spec)
return -ESRCH;
- if (arg_num >= BPF_USDT_MAX_ARG_CNT || arg_num >= spec->arg_cnt)
+ if (arg_num >= BPF_USDT_MAX_ARG_CNT)
+ return -ENOENT;
+ barrier_var(arg_num);
+ if (arg_num >= spec->arg_cnt)
return -ENOENT;
arg_spec = &spec->args[arg_num];
@@ -169,6 +223,27 @@ int bpf_usdt_arg(struct pt_regs *ctx, __u64 arg_num, long *res)
val >>= arg_spec->arg_bitshift;
#endif
break;
+ case BPF_USDT_ARG_SIB:
+ /* Arg is in memory addressed by SIB (Scale-Index-Base) mode
+ * (e.g., "-1@-96(%rbp,%rax,8)" in USDT arg spec). We first
+ * fetch the base register contents and the index register
+ * contents from pt_regs. Then we calculate the final address
+ * as base + (index * scale) + offset, and do a user-space
+ * probe read to fetch the argument value.
+ */
+ err = bpf_probe_read_kernel(&val, sizeof(val), (void *)ctx + arg_spec->reg_off);
+ if (err)
+ return err;
+ err = bpf_probe_read_kernel(&idx, sizeof(idx), (void *)ctx + arg_spec->idx_reg_off);
+ if (err)
+ return err;
+ err = bpf_probe_read_user(&val, sizeof(val), (void *)(val + (idx << arg_spec->scale_bitshift) + arg_spec->val_off));
+ if (err)
+ return err;
+#if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+ val >>= arg_spec->arg_bitshift;
+#endif
+ break;
default:
return -EINVAL;
}
@@ -211,18 +286,18 @@ 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)
/*
generated by cgit (git 2.34.1) at 2025-12-25 18:03:51 +0000