DSOs were held on a list for fast iteration and in an rbtree for fast
finds.
Switch to using a lazily sorted array where iteration is just iterating
through the array and binary searches are the same complexity as
searching the rbtree.
The find may need to sort the array first which does increase the
complexity, but add operations have lower complexity and overall the
complexity should remain about the same.
The set name operations on the dso just records that the array is no
longer sorted, avoiding complexity in rebalancing the rbtree.
Tighter locking discipline is enforced to avoid the array being resorted
while long and short names or ids are changed.
The array is smaller in size, replacing 6 pointers with 2, and so even
with extra allocated space in the array, the array may be 50%
unoccupied, the memory saving should be at least 2x.
Committer testing:
On a previous version of this patchset we were getting a lot of warnings
about deleting a DSO still on a list, now it is ok:
root@x1:~# perf probe -l
root@x1:~# perf probe finish_task_switch
Added new event:
probe:finish_task_switch (on finish_task_switch)
You can now use it in all perf tools, such as:
perf record -e probe:finish_task_switch -aR sleep 1
root@x1:~# perf probe -l
probe:finish_task_switch (on finish_task_switch@kernel/sched/core.c)
root@x1:~# perf trace -e probe:finish_task_switch/max-stack=8/ --max-events=1
0.000 migration/0/19 probe:finish_task_switch(__probe_ip: -1894408688)
finish_task_switch.isra.0 ([kernel.kallsyms])
__schedule ([kernel.kallsyms])
schedule ([kernel.kallsyms])
smpboot_thread_fn ([kernel.kallsyms])
kthread ([kernel.kallsyms])
ret_from_fork ([kernel.kallsyms])
ret_from_fork_asm ([kernel.kallsyms])
root@x1:~#
root@x1:~# perf probe -d probe:*
Removed event: probe:finish_task_switch
root@x1:~# perf probe -l
root@x1:~#
I also ran the full 'perf test' suite after applying this one, no
regressions.
Signed-off-by: Ian Rogers <irogers@google.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Cc: Ben Gainey <ben.gainey@arm.com>
Cc: Changbin Du <changbin.du@huawei.com>
Cc: Chengen Du <chengen.du@canonical.com>
Cc: Colin Ian King <colin.i.king@gmail.com>
Cc: Dima Kogan <dima@secretsauce.net>
Cc: Ilkka Koskinen <ilkka@os.amperecomputing.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@arm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: K Prateek Nayak <kprateek.nayak@amd.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Leo Yan <leo.yan@linux.dev>
Cc: Li Dong <lidong@vivo.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paran Lee <p4ranlee@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Song Liu <song@kernel.org>
Cc: Sun Haiyong <sunhaiyong@loongson.cn>
Cc: Thomas Richter <tmricht@linux.ibm.com>
Cc: Tiezhu Yang <yangtiezhu@loongson.cn>
Cc: Yanteng Si <siyanteng@loongson.cn>
Cc: zhaimingbing <zhaimingbing@cmss.chinamobile.com>
Link: https://lore.kernel.org/r/20240504213803.218974-2-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
To aggregate accesses to the same data type, add 'data_types' tree in
DSO to maintain data types and find it by name and size.
It might have different data types that happen to have the same name,
so it also compares the size of the type.
Even if it doesn't 100% guarantee, it reduces the possibility of
mis-handling of such conflicts.
And I don't think it's common to have different types with the same
name.
Committer notes:
Very few cases on the Linux kernel, but there are some different types
with the same name, unsure if there is a debug mode in libbpf dedup that
warns about such cases, but there are provisions in pahole for that,
see:
"emit: Notice type shadowing, i.e. multiple types with the same name (enum, struct, union, etc)"
https://git.kernel.org/pub/scm/devel/pahole/pahole.git/commit/?id=4f332dbfd02072e4f410db7bdcda8d6e3422974b
$ pahole --compile > vmlinux.h
$ rm -f a ; make a
cc a.c -o a
$ grep __[0-9] vmlinux.h
union irte__1 {
struct map_info__1;
struct map_info__1 {
struct map_info__1 * next; /* 0 8 */
$
drivers/iommu/amd/amd_iommu_types.h 'union irte'
include/linux/dmar.h 'struct irte'
include/linux/device-mapper.h:
union map_info {
void *ptr;
};
include/linux/mtd/map.h:
struct map_info {
const char *name;
unsigned long size;
resource_size_t phys;
<SNIP>
kernel/events/uprobes.c:
struct map_info {
struct map_info *next;
struct mm_struct *mm;
unsigned long vaddr;
};
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: linux-toolchains@vger.kernel.org
Cc: linux-trace-devel@vger.kernel.org
Link: https://lore.kernel.org/r/20231213001323.718046-5-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Update "struct dso" to include new member "is_kmod".
This new field will determine if the file is a kernel
module or not.
To resolve the address from a sample, perf looks at the
DSO maps. In case of address from a kernel module, there
were some address found to be not resolved. This was
observed while running perf test for "Object code reading".
Though the ip falls beteen the start address of the loaded
module (perf map->start ) and end address ( perf map->end),
it was unresolved.
This was happening because in some cases for kernel
modules, address from sample points to stub instructions.
To identify if the DSO is a kernel module, the new field
"is_kmod" is added to "struct dso".
Reported-by: Disha Goel <disgoel@linux.ibm.com>
Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: kjain@linux.ibm.com
Cc: maddy@linux.ibm.com
Cc: disgoel@linux.vnet.ibm.com
Cc: linuxppc-dev@lists.ozlabs.org
Link: https://lore.kernel.org/r/20230928075213.84392-2-atrajeev@linux.vnet.ibm.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Update "struct dso" to include new member "text_end".
This new field will represent the offset for end of text
section for a dso. For elf, this value is derived as:
sh_size (Size of section in byes) + sh_offset (Section file
offst) of the elf header for text.
For bfd, this value is derived as:
1. For PE file,
section->size + ( section->vma - dso->text_offset)
2. Other cases:
section->filepos (file position) + section->size (size of
section)
To resolve the address from a sample, perf looks at the
DSO maps. In case of address from a kernel module, there
were some address found to be not resolved. This was
observed while running perf test for "Object code reading".
Though the ip falls beteen the start address of the loaded
module (perf map->start ) and end address ( perf map->end),
it was unresolved.
Example:
Reading object code for memory address: 0xc008000007f0142c
File is: /lib/modules/6.5.0-rc3+/kernel/fs/xfs/xfs.ko
On file address is: 0x1114cc
Objdump command is: objdump -z -d --start-address=0x11142c --stop-address=0x1114ac /lib/modules/6.5.0-rc3+/kernel/fs/xfs/xfs.ko
objdump read too few bytes: 128
test child finished with -1
Here, module is loaded at:
# cat /proc/modules | grep xfs
xfs 2228224 3 - Live 0xc008000007d00000
From objdump for xfs module, text section is:
text 0010f7bc 0000000000000000 0000000000000000 000000a0 2**4
Here the offset for 0xc008000007f0142c ie 0x112074 falls out
.text section which is up to 0x10f7bc.
In this case for module, the address 0xc008000007e11fd4 is pointing
to stub instructions. This address range represents the module stubs
which is allocated on module load and hence is not part of DSO offset.
To identify such address, which falls out of text
section and within module end, added the new field "text_end" to
"struct dso".
Reported-by: Disha Goel <disgoel@linux.ibm.com>
Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Reviewed-by: Adrian Hunter <adrian.hunter@intel.com>
Reviewed-by: Kajol Jain <kjain@linux.ibm.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: maddy@linux.ibm.com
Cc: disgoel@linux.vnet.ibm.com
Cc: linuxppc-dev@lists.ozlabs.org
Link: https://lore.kernel.org/r/20230928075213.84392-1-atrajeev@linux.vnet.ibm.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
segbase is the address of .eh_frame_hdr and table_data is segbase plus
the header size. find_proc_info computes segbase as `map->start +
segbase - map->pgoff` which is wrong when
* .eh_frame_hdr and .text are in different PT_LOAD program headers
* and their p_vaddr difference does not equal their p_offset difference
Since 10.0, ld.lld's default --rosegment -z noseparate-code layout has
such R and RX PT_LOAD program headers.
ld.lld (default) => perf report fails to unwind `perf record
--call-graph dwarf` recorded data
ld.lld --no-rosegment => ok (trivial, no R PT_LOAD)
ld.lld -z separate-code => ok but by luck: there are two PT_LOAD but
their p_vaddr difference equals p_offset difference
ld.bfd -z noseparate-code => ok (trivial, no R PT_LOAD)
ld.bfd -z separate-code (default for Linux/x86) => ok but by luck:
there are two PT_LOAD but their p_vaddr difference equals p_offset
difference
To fix the issue, compute segbase as dso's base address plus
PT_GNU_EH_FRAME's p_vaddr. The base address is computed by iterating
over all dso-associated maps and then subtract the first PT_LOAD p_vaddr
(the minimum guaranteed by generic ABI) from the minimum address.
In libunwind, find_proc_info transitively called by unw_step is cached,
so the iteration overhead is acceptable.
Reported-by: Sebastian Ullrich <sebasti@nullri.ch>
Reviewed-by: Ian Rogers <irogers@google.com>
Signed-off-by: Fangrui Song <maskray@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: llvm@lists.linux.dev
Link: https://github.com/ClangBuiltLinux/linux/issues/1646
Link: https://lore.kernel.org/r/20220527182039.673248-1-maskray@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
With shorter md5 build ids we need to align their paths properly with
other build ids:
$ perf buildid-list
17f4e448cc746582ea1881528deb549f7fdb3fd5 [kernel.kallsyms]
a50e350e97c43b4708d09bcd85ebfff7 .../tools/perf/buildid-ex-md5
1805c738c8f3ec0f47b7ea09080c28f34d18a82b /usr/lib64/ld-2.31.so
$
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/r/20201013192441.1299447-9-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Replace build_id byte array with struct build_id object and all the code
that references it.
The objective is to carry size together with build id array, so it's
better to keep both together.
This is preparatory change for following patches, and there's no
functional change.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/r/20201013192441.1299447-2-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Rename enum dso_kernel_type to enum dso_space_type, which seems like
better fit.
Committer notes:
This is used with 'struct dso'->kernel, which once was a boolean, so
DSO_SPACE__USER is zero, !zero means some sort of kernel space, be it
the host kernel space or a guest kernel space.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array
member[1][2], introduced in C99:
struct foo {
int stuff;
struct boo array[];
};
By making use of the mechanism above, we will get a compiler warning in
case the flexible array does not occur last in the structure, which will
help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.
Also, notice that, dynamic memory allocations won't be affected by this
change:
"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]
sizeof(flexible-array-member) triggers a warning because flexible array
members have incomplete type[1]. There are some instances of code in
which the sizeof operator is being incorrectly/erroneously applied to
zero-length arrays and the result is zero. Such instances may be hiding
some bugs. So, this work (flexible-array member conversions) will also
help to get completely rid of those sorts of issues.
This issue was found with the help of Coccinelle.
[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 7649773293 ("cxgb3/l2t: Fix undefined behaviour")
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Gustavo A. R. Silva <gustavo@embeddedor.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20200515172926.GA31976@embeddedor
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
And take it into account when looking up DSOs when we have the dso_id
fields obtained from somewhere, like from PERF_RECORD_MMAP2 records.
Instances of struct map pointing to the same DSO pathname but with
anything in dso_id different are in fact different DSOs, so better have
different 'struct dso' instances to reflect that. At some point we may
want to get copies of the contents of the different objects if we want
to do correct annotation or other analysis.
With this we get 'struct map' 24 bytes leaner:
$ pahole -C map ~/bin/perf
struct map {
union {
struct rb_node rb_node __attribute__((__aligned__(8))); /* 0 24 */
struct list_head node; /* 0 16 */
} __attribute__((__aligned__(8))); /* 0 24 */
u64 start; /* 24 8 */
u64 end; /* 32 8 */
_Bool erange_warned:1; /* 40: 0 1 */
_Bool priv:1; /* 40: 1 1 */
/* XXX 6 bits hole, try to pack */
/* XXX 3 bytes hole, try to pack */
u32 prot; /* 44 4 */
u64 pgoff; /* 48 8 */
u64 reloc; /* 56 8 */
/* --- cacheline 1 boundary (64 bytes) --- */
u64 (*map_ip)(struct map *, u64); /* 64 8 */
u64 (*unmap_ip)(struct map *, u64); /* 72 8 */
struct dso * dso; /* 80 8 */
refcount_t refcnt; /* 88 4 */
u32 flags; /* 92 4 */
/* size: 96, cachelines: 2, members: 13 */
/* sum members: 92, holes: 1, sum holes: 3 */
/* sum bitfield members: 2 bits, bit holes: 1, sum bit holes: 6 bits */
/* forced alignments: 1 */
/* last cacheline: 32 bytes */
} __attribute__((__aligned__(8)));
$
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/n/tip-g4hxxmraplo7wfjmk384mfsb@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Introduce a new dso type DSO_BINARY_TYPE__BPF_PROG_INFO for BPF programs. In
symbol__disassemble(), DSO_BINARY_TYPE__BPF_PROG_INFO dso will call into a new
function symbol__disassemble_bpf() in an upcoming patch, where annotation line
information is filled based bpf_prog_info and btf saved in given perf_env.
Committer notes:
Removed the unnamed union with 'bpf_prog' and 'cache' in 'struct dso',
to fix this bug when exiting 'perf top':
# perf top
perf: Segmentation fault
-------- backtrace --------
perf[0x5a785a]
/lib64/libc.so.6(+0x385bf)[0x7fd68443c5bf]
perf(rb_first+0x2b)[0x4d6eeb]
perf(dso__delete+0xb7)[0x4dffb7]
perf[0x4f9e37]
perf(perf_session__delete+0x64)[0x504df4]
perf(cmd_top+0x1957)[0x454467]
perf[0x4aad18]
perf(main+0x61c)[0x42ec7c]
/lib64/libc.so.6(__libc_start_main+0xf2)[0x7fd684428412]
perf(_start+0x2d)[0x42eead]
#
# addr2line -fe ~/bin/perf 0x4dffb7
dso_cache__free
/home/acme/git/perf/tools/perf/util/dso.c:713
That is trying to access the dso->data.cache, and that is not used with
BPF programs, so we end up accessing what is in bpf_prog.first_member,
b00m.
Signed-off-by: Song Liu <songliubraving@fb.com>
Reviewed-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stanislav Fomichev <sdf@google.com>
Cc: kernel-team@fb.com
Link: http://lkml.kernel.org/r/20190312053051.2690567-13-songliubraving@fb.com
[ split from a larger patch ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Store a decompression ID in 'struct kmod_path', so it can be later
stored in 'struct dso'.
Switch 'struct kmod_path's 'comp' from 'bool' to 'int' to return the
compressions array index. Add 0 index item into compressions array, so
that the comp usage stays as it was: 0 - no compression, != 0
compression index.
Update the kmod_path tests.
Committer notes:
Use a designated initializer + terminating comma, e.g. { .fmt = NULL, }, to fix
the build in several distros:
centos:6: util/dso.c:201: error: missing initializer
centos:6: util/dso.c:201: error: (near initialization for 'compressions[0].decompress')
debian:9: util/dso.c:201:24: error: missing field 'decompress' initializer [-Werror,-Wmissing-field-initializers]
fedora:25: util/dso.c:201:24: error: missing field 'decompress' initializer [-Werror,-Wmissing-field-initializers]
fedora:26: util/dso.c:201:24: error: missing field 'decompress' initializer [-Werror,-Wmissing-field-initializers]
fedora:27: util/dso.c:201:24: error: missing field 'decompress' initializer [-Werror,-Wmissing-field-initializers]
oraclelinux:6: util/dso.c:201: error: missing initializer
oraclelinux:6: util/dso.c:201: error: (near initialization for 'compressions[0].decompress')
ubuntu:12.04.5: util/dso.c:201:2: error: missing initializer [-Werror=missing-field-initializers]
ubuntu:12.04.5: util/dso.c:201:2: error: (near initialization for 'compressions[0].decompress') [-Werror=missing-field-initializers]
ubuntu:16.04: util/dso.c:201:24: error: missing field 'decompress' initializer [-Werror,-Wmissing-field-initializers]
ubuntu:16.10: util/dso.c:201:24: error: missing field 'decompress' initializer [-Werror,-Wmissing-field-initializers]
ubuntu:16.10: util/dso.c:201:24: error: missing field 'decompress' initializer [-Werror,-Wmissing-field-initializers]
ubuntu:17.10: util/dso.c:201:24: error: missing field 'decompress' initializer [-Werror,-Wmissing-field-initializers]
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20180817094813.15086-7-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Remove the split of symbol tables for data (MAP__VARIABLE) and for
functions (MAP__FUNCTION), its unneeded and there were various places
doing two lookups to find a symbol, so simplify this.
We still will consider only the symbols that matched the filters in
place, i.e. see the (elf_(sec,sym)|symbol_type)__filter() routines in
the patch, just so that we consider only the same symbols as before,
to reduce the possibility of regressions.
All the tests on 50-something build environments, in varios versions
of lots of distros and cross build environments were performed without
build regressions, as usual with all pull requests the other tests were
also performed: 'perf test' and 'make -C tools/perf build-test'.
Also this was done at a great granularity so that regressions can be
bisected more easily.
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-hiq0fy2rsleupnqqwuojo1ne@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
