When unwinding using frame pointers on ARM64, the return address of the
current function may not have been pushed into the stack when a function
was interrupted, which makes perf show an incorrect call graph to the
user.
Consider the following example program:
void leaf() {
/* long computation */
}
void parent() {
// (1)
leaf();
// (2)
}
... could be compiled into (using gcc -fno-inline -fno-omit-frame-pointer):
leaf:
/* long computation */
nop
ret
parent:
// (1)
stp x29, x30, [sp, -16]!
mov x29, sp
bl parent
nop
ldp x29, x30, [sp], 16
// (2)
ret
If the program is interrupted at (1), (2), or any point in "leaf:", the
call graph will skip the callers of the current function. We can unwind
using the dwarf info and check if the return addr is the same as the LR
register, and inject the missing frame into the call graph.
Before this patch, the above example shows the following call-graph when
recording using "--call-graph fp" mode in ARM64:
# Children Self Command Shared Object Symbol
# ........ ........ ........ ................ ......................
#
99.86% 99.86% program3 program3 [.] leaf
|
---_start
__libc_start_main
main
leaf
As can be seen, the "parent" function is missing. This is specially
problematic in "leaf" because for leaf functions the compiler may always
omit pushing the return addr into the stack. After this patch, it shows
the correct graph:
# Children Self Command Shared Object Symbol
# ........ ........ ........ ................ ......................
#
99.86% 99.86% program3 program3 [.] leaf
|
---_start
__libc_start_main
main
parent
leaf
Reviewed-by: James Clark <james.clark@arm.com>
Signed-off-by: Alexandre Truong <alexandre.truong@arm.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: John Garry <john.garry@huawei.com>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Will Deacon <will@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org
Link: https://lore.kernel.org/r/20211217154521.80603-7-german.gomez@arm.com
Signed-off-by: German Gomez <german.gomez@arm.com>
[ Rename machine__normalize_is() to machine__normalized_is(), as suggested by James Clark ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
And pick the shortest name: 'struct maps'.
The split existed because we used to have two groups of maps, one for
functions and one for variables, but that only complicated things,
sometimes we needed to figure out what was at some address and then had
to first try it on the functions group and if that failed, fall back to
the variables one.
That split is long gone, so for quite a while we had only one struct
maps per struct map_groups, simplify things by combining those structs.
First patch is the minimum needed to merge both, follow up patches will
rename 'thread->mg' to 'thread->maps', etc.
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-hom6639ro7020o708trhxh59@git.kernel.org
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>
To get closer to upstream and check if we need to sync more UAPI
headers, pick up fixes for libbpf that prevent perf's container tests
from completing successfuly, etc.
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
On s390 the modules loaded in memory have the text segment located after
the GOT and Relocation table. This can be seen with this output:
[root@m35lp76 perf]# fgrep qeth /proc/modules
qeth 151552 1 qeth_l2, Live 0x000003ff800b2000
...
[root@m35lp76 perf]# cat /sys/module/qeth/sections/.text
0x000003ff800b3990
[root@m35lp76 perf]#
There is an offset of 0x1990 bytes. The size of the qeth module is
151552 bytes (0x25000 in hex).
The location of the GOT/relocation table at the beginning of a module is
unique to s390.
commit 203d8a4aa6 ("perf s390: Fix 'start' address of module's map")
adjusts the start address of a module in the map structures, but does
not adjust the size of the modules. This leads to overlapping of module
maps as this example shows:
[root@m35lp76 perf] # ./perf report -D
0 0 0xfb0 [0xa0]: PERF_RECORD_MMAP -1/0: [0x3ff800b3990(0x25000)
@ 0]: x /lib/modules/.../qeth.ko.xz
0 0 0x1050 [0xb0]: PERF_RECORD_MMAP -1/0: [0x3ff800d85a0(0x8000)
@ 0]: x /lib/modules/.../ip6_tables.ko.xz
The module qeth.ko has an adjusted start address modified to b3990, but
its size is unchanged and the module ends at 0x3ff800d8990. This end
address overlaps with the next modules start address of 0x3ff800d85a0.
When the size of the leading GOT/Relocation table stored in the
beginning of the text segment (0x1990 bytes) is subtracted from module
qeth end address, there are no overlaps anymore:
0x3ff800d8990 - 0x1990 = 0x0x3ff800d7000
which is the same as
0x3ff800b2000 + 0x25000 = 0x0x3ff800d7000.
To fix this issue, also adjust the modules size in function
arch__fix_module_text_start(). Add another function parameter named size
and reduce the size of the module when the text segment start address is
changed.
Output after:
0 0 0xfb0 [0xa0]: PERF_RECORD_MMAP -1/0: [0x3ff800b3990(0x23670)
@ 0]: x /lib/modules/.../qeth.ko.xz
0 0 0x1050 [0xb0]: PERF_RECORD_MMAP -1/0: [0x3ff800d85a0(0x7a60)
@ 0]: x /lib/modules/.../ip6_tables.ko.xz
Reported-by: Stefan Liebler <stli@linux.ibm.com>
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Hendrik Brueckner <brueckner@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: stable@vger.kernel.org
Fixes: 203d8a4aa6 ("perf s390: Fix 'start' address of module's map")
Link: http://lkml.kernel.org/r/20190724122703.3996-1-tmricht@linux.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
At the cost of an extra pointer, we can avoid the O(logN) cost of
finding the first element in the tree (smallest node), which is
something required for nearly every operation dealing with
machine->guests and threads->entries.
The conversion is straightforward, however, it's worth noticing that the
rb_erase_init() calls have been replaced by rb_erase_cached() which has
no _init() flavor, however, the node is explicitly cleared next anyway,
which was redundant until now.
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/20181206191819.30182-3-dave@stgolabs.net
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This patch handles PERF_RECORD_KSYMBOL in perf record/report.
Specifically, map and symbol are created for ksymbol register, and
removed for ksymbol unregister.
This patch also sets perf_event_attr.ksymbol properly. The flag is ON by
default.
Committer notes:
Use proper inttypes.h for u64, fixing the build in some environments
like in the android NDK r15c targetting ARM 32-bit.
I.e. fixing this build error:
util/event.c: In function 'perf_event__fprintf_ksymbol':
util/event.c:1489:10: error: format '%lx' expects argument of type 'long unsigned int', but argument 3 has type 'u64' [-Werror=format=]
event->ksymbol_event.flags, event->ksymbol_event.name);
^
cc1: all warnings being treated as errors
Signed-off-by: Song Liu <songliubraving@fb.com>
Reviewed-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: kernel-team@fb.com
Cc: netdev@vger.kernel.org
Link: http://lkml.kernel.org/r/20190117161521.1341602-6-songliubraving@fb.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Ian Rogers
Alexandre Truong
Adrian Hunter
Jiri Olsa
Namhyung Kim
Arnaldo Carvalho de Melo
Thomas Richter
Davidlohr Bueso
Song Liu
Mark Drayton