mirror of
https://github.com/openbsd/src.git
synced 2026-04-21 12:44:33 +00:00
update documentation for btrace(8) and dt(4) so it matches
the code we have in tree. Lot of suggestions from claudio@ and ingo@. OK deraadt@
This commit is contained in:
sashan
@@ -1,4 +1,4 @@
|
||||
/* $OpenBSD: uprofile.bt,v 1.1 2023/05/12 14:34:00 claudio Exp $ */
|
||||
/* $OpenBSD: uprofile.bt,v 1.2 2025/10/05 22:31:54 sashan Exp $ */
|
||||
|
||||
/*
|
||||
* uprofile.bt Userland profiling (stack sampling) at 100Hz.
|
||||
@@ -9,8 +9,13 @@
|
||||
*
|
||||
* The PID of the to be monitored process is the first optional argument to
|
||||
* btrace(8).
|
||||
* This only works for a single static binary where everything was compiled
|
||||
* with -fno-omit-frame-pointer.
|
||||
*
|
||||
* To collect profiling data for process with pid 12345 one uses uprofile.bt
|
||||
* script as follows:
|
||||
* btrace /usr/share/btrace/uprofile.bt 12345
|
||||
* after hitting Ctrl+C the btrace process terminates and writes collected
|
||||
* profiling data to standard output. This only works for ELF objects which
|
||||
* are compiled with -fno-omit-frame-pointer.
|
||||
*/
|
||||
profile:hz:100 / pid == $1 / {
|
||||
@[ustack] = count();
|
||||
|
||||
@@ -1,4 +1,4 @@
|
||||
.\" $OpenBSD: dt.4,v 1.7 2020/12/02 07:00:42 anton Exp $
|
||||
.\" $OpenBSD: dt.4,v 1.8 2025/10/05 22:31:54 sashan Exp $
|
||||
.\"
|
||||
.\" Copyright (c) 2019 Martin Pieuchot <mpi@openbsd.org>
|
||||
.\"
|
||||
@@ -14,7 +14,7 @@
|
||||
.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
|
||||
.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
|
||||
.\"
|
||||
.Dd $Mdocdate: December 2 2020 $
|
||||
.Dd $Mdocdate: October 5 2025 $
|
||||
.Dt DT 4
|
||||
.Os
|
||||
.Sh NAME
|
||||
@@ -77,6 +77,58 @@ struct dtioc_req {
|
||||
uint64_t dtrq_evtflags;
|
||||
};
|
||||
.Ed
|
||||
.It Dv DTIOCRDVNODE Fa "struct *dtioc_rdvn"
|
||||
Resolve the instruction pointer from the traced process to the ELF object.
|
||||
.Bd -literal
|
||||
struct dtioc_rdvn {
|
||||
pid_t dtrv_pid;
|
||||
int dtrv_fd;
|
||||
caddr_t dtrv_va;
|
||||
caddr_t dtrv_offset;
|
||||
caddr_t dtrv_start;
|
||||
size_t dtrv_len;
|
||||
};
|
||||
.Ed
|
||||
.Pp
|
||||
The caller populates
|
||||
.Fa dtrv_pid
|
||||
with the process ID of the traced process and
|
||||
.Fa dtrv_va
|
||||
with the program counter address to look up.
|
||||
.Pp
|
||||
On success, the remaining members are populated.
|
||||
.Fa dtrv_fd
|
||||
is the file descriptor to the DSO file that
|
||||
.Fa dtrv_va
|
||||
belongs to.
|
||||
.FA dtrv_len
|
||||
is the length of the DSO file.
|
||||
.Fa dtrv_offset
|
||||
and
|
||||
.Fa dtrv_start
|
||||
are the relative offset of
|
||||
.Fa dtrv_va
|
||||
to the start of the text segment and the base address of that segment
|
||||
respectively.
|
||||
.Pp
|
||||
To calculate the relative offset of
|
||||
.Fa dtrv_va
|
||||
in the DSO the following calculation can be used:
|
||||
.Pp
|
||||
.Dl iOffset = dtrv_va - dtrv_start + dtrv_offset
|
||||
.Pp
|
||||
The segment can be found by walking the ELF program headers and looking
|
||||
for the mapping where iOffset is included in the range
|
||||
[GElf_Phdr.p_offset, GElf_Phdr.p_offset + GElf_Phdr.p_filesz)
|
||||
.Pp
|
||||
Using the
|
||||
.Vt GElf_Phdr.p_vaddr
|
||||
the base address of the segment can be calculated by
|
||||
.Dl lbase = dtrv_start - GElf_Phdr.p_vaddr
|
||||
.Pp
|
||||
For symbol lookups the offset can now be calculated as
|
||||
.Dl symOffset = dtrv_va - lbase
|
||||
.El
|
||||
.El
|
||||
.Sh FILES
|
||||
.Bl -tag -width /dev/dt -compact
|
||||
|
||||
@@ -1,4 +1,4 @@
|
||||
.\" $OpenBSD: btrace.8,v 1.10 2025/05/18 20:09:58 schwarze Exp $
|
||||
.\" $OpenBSD: btrace.8,v 1.11 2025/10/05 22:31:54 sashan Exp $
|
||||
.\"
|
||||
.\" Copyright (c) 2019 Martin Pieuchot <mpi@openbsd.org>
|
||||
.\"
|
||||
@@ -14,7 +14,7 @@
|
||||
.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
|
||||
.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
|
||||
.\"
|
||||
.Dd $Mdocdate: May 18 2025 $
|
||||
.Dd $Mdocdate: October 5 2025 $
|
||||
.Dt BTRACE 8
|
||||
.Os
|
||||
.Sh NAME
|
||||
@@ -23,7 +23,6 @@
|
||||
.Sh SYNOPSIS
|
||||
.Nm btrace
|
||||
.Op Fl lnv
|
||||
.Op Fl p Ar elffile
|
||||
.Ar programfile | Fl e Ar program
|
||||
.Op Ar argument ...
|
||||
.Sh DESCRIPTION
|
||||
@@ -56,12 +55,6 @@ List all available probes.
|
||||
.It Fl n
|
||||
No action.
|
||||
Parse the program and then exit.
|
||||
.It Fl p Ar elffile
|
||||
Load symbols from the
|
||||
.Ar elffile
|
||||
to convert
|
||||
.Va ustack
|
||||
addresses into function names.
|
||||
.It Fl v
|
||||
Verbose mode.
|
||||
Causes
|
||||
|
||||
@@ -1,4 +1,4 @@
|
||||
/* $OpenBSD: btrace.c,v 1.98 2025/09/22 07:49:43 sashan Exp $ */
|
||||
/* $OpenBSD: btrace.c,v 1.99 2025/10/05 22:31:54 sashan Exp $ */
|
||||
|
||||
/*
|
||||
* Copyright (c) 2019 - 2023 Martin Pieuchot <mpi@openbsd.org>
|
||||
@@ -230,7 +230,7 @@ main(int argc, char *argv[])
|
||||
__dead void
|
||||
usage(void)
|
||||
{
|
||||
fprintf(stderr, "usage: %s [-lnv] [-p elffile] "
|
||||
fprintf(stderr, "usage: %s [-lnv] "
|
||||
"programfile | -e program [argument ...]\n", getprogname());
|
||||
exit(1);
|
||||
}
|
||||
|
||||
Reference in New Issue
Block a user