Normally objtool ensures a function keeps the stack layout invariant.
But there is a useful exception, it is possible to stuff the return
stack in order to 'inject' a 'call':
push $fun
ret
In this case the invariant mentioned above is violated.
Add an objtool HINT to annotate this and allow a function exit with a
modified stack frame.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200416115118.690601403@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Teach objtool a little more about IRET so that we can avoid using the
SAVE/RESTORE annotation. In particular, make the weird corner case in
insn->restore go away.
The purpose of that corner case is to deal with the fact that
UNWIND_HINT_RESTORE lands on the instruction after IRET, but that
instruction can end up being outside the basic block, consider:
if (cond)
sync_core()
foo();
Then the hint will land on foo(), and we'll encounter the restore
hint without ever having seen the save hint.
By teaching objtool about the arch specific exception frame size, and
assuming that any IRET in an STT_FUNC symbol is an exception frame
sized POP, we can remove the use of save/restore hints for this code.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200416115118.631224674@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Instruction sets can include more or less complex operations which might
not fit the currently defined set of stack_ops.
Combining more than one stack_op provides more flexibility to describe
the behaviour of an instruction. This also reduces the need to define
new stack_ops specific to a single instruction set.
Allow instruction decoders to generate multiple stack_op per
instruction.
Signed-off-by: Julien Thierry <jthierry@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200327152847.15294-11-jthierry@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
If the prefix of section name is not '.rodata', the following
function call can never return 0.
strcmp(sec->name, C_JUMP_TABLE_SECTION)
So the name comparison is pointless, just remove it.
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Some CFI definitions used by generic objtool code have no reason to vary
from one architecture to another. Keep those definitions in generic
code and move the arch-specific ones to a new arch-specific header.
Signed-off-by: Julien Thierry <jthierry@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The initial register state is set up by arch specific code. Use the
value the arch code has set when restoring registers from the stack.
Suggested-by: Raphael Gault <raphael.gault@arm.com>
Signed-off-by: Julien Thierry <jthierry@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The .alternatives section can contain entries with no original
instructions. Objtool will currently crash when handling such an entry.
Just skip that entry, but still give a warning to discourage useless
entries.
Signed-off-by: Julien Thierry <jthierry@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
When a function fails its validation, it might leave a stale state
that will be used for the validation of other functions. That would
cause false warnings on potentially valid functions.
Reset the instruction state before the validation of each individual
function.
Signed-off-by: Julien Thierry <jthierry@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
POP operations are already in the code path where the destination
operand is OP_DEST_REG. There is no need to check the operand type
again.
Signed-off-by: Julien Thierry <jthierry@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Currently, the check of tools files against kernel equivalent is only
done after every object file has been built. This means one might fix
build issues against outdated headers without seeing a warning about
this.
Check headers before any object is built. Also, make it part of a
FORCE'd recipe so every attempt to build objtool will report the
outdated headers (if any).
Signed-off-by: Julien Thierry <jthierry@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Sometimes, WARN_FUNC() and other users of symbol_by_offset() will
associate the first instruction of a symbol with the symbol preceding
it. This is because symbol->offset + symbol->len is already outside of
the symbol's range.
Fixes: 2a362ecc3e ("objtool: Optimize find_symbol_*() and read_symbols()")
Signed-off-by: Julien Thierry <jthierry@redhat.com>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Merge misc fixes from Andrew Morton:
"15 fixes"
* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
tools/vm: fix cross-compile build
coredump: fix null pointer dereference on coredump
mm: shmem: disable interrupt when acquiring info->lock in userfaultfd_copy path
shmem: fix possible deadlocks on shmlock_user_lock
vmalloc: fix remap_vmalloc_range() bounds checks
mm/shmem: fix build without THP
mm/ksm: fix NULL pointer dereference when KSM zero page is enabled
tools/build: tweak unused value workaround
checkpatch: fix a typo in the regex for $allocFunctions
mm, gup: return EINTR when gup is interrupted by fatal signals
mm/hugetlb: fix a addressing exception caused by huge_pte_offset
MAINTAINERS: add an entry for kfifo
mm/userfaultfd: disable userfaultfd-wp on x86_32
slub: avoid redzone when choosing freepointer location
sh: fix build error in mm/init.c
Pull virtio fixes and cleanups from Michael Tsirkin:
- Some bug fixes
- Cleanup a couple of issues that surfaced meanwhile
- Disable vhost on ARM with OABI for now - to be fixed fully later in
the cycle or in the next release.
* tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost: (24 commits)
vhost: disable for OABI
virtio: drop vringh.h dependency
virtio_blk: add a missing include
virtio-balloon: Avoid using the word 'report' when referring to free page hinting
virtio-balloon: make virtballoon_free_page_report() static
vdpa: fix comment of vdpa_register_device()
vdpa: make vhost, virtio depend on menu
vdpa: allow a 32 bit vq alignment
drm/virtio: fix up for include file changes
remoteproc: pull in slab.h
rpmsg: pull in slab.h
virtio_input: pull in slab.h
remoteproc: pull in slab.h
virtio-rng: pull in slab.h
virtgpu: pull in uaccess.h
tools/virtio: make asm/barrier.h self contained
tools/virtio: define aligned attribute
virtio/test: fix up after IOTLB changes
vhost: Create accessors for virtqueues private_data
vdpasim: Return status in vdpasim_get_status
...
On AMD, the state of the VMCB is undefined after a shutdown VMEXIT. KVM
takes a very conservative approach to that and resets the guest altogether
when that happens. This causes the set_memory_region_test to fail
because the RIP is 0xfff0 (the reset vector). Restrict the RIP test
to KVM_EXIT_INTERNAL_ERROR in order to fix this.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
To integrate with logrotate, we have a signal handler that will re-open
the logfile.
Assuming we have a systemd unit file with
ExecStart=kvm_stat -dtc -s 10 -L /var/log/kvm_stat.csv
ExecReload=/bin/kill -HUP $MAINPID
and a logrotate config featuring
postrotate
/bin/systemctl reload kvm_stat.service
endscript
Then the overall flow will look like this:
(1) systemd starts kvm_stat, logging to A.
(2) At some point, logrotate runs, moving A to B.
kvm_stat continues to write to B at this point.
(3) After rotating, logrotate restarts the kvm_stat unit via systemctl.
(4) The kvm_stat unit sends a SIGHUP to kvm_stat, finally making it
switch over to writing to A again.
Note that in order to keep the structure of the cvs output in tact, we
make sure to, in contrast to the standard log format, only write the
header once at the beginning of a file. This implies that the header is
suppressed when appending to an existing file. Unlike with the standard
format, where we append to an existing file by starting out with a
header.
Signed-off-by: Stefan Raspl <raspl@de.ibm.com>
Message-Id: <20200402085705.61155-3-raspl@linux.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This patch adds a test to test_verifier that writes the lower 8 bits of
R10 (aka FP) using BPF_B to an array map and reads the result back. The
expected behavior is that the result should be the same as first copying
R10 to R9, and then storing / loading the lower 8 bits of R9.
This test catches a bug that was present in the x86-64 JIT that caused
an incorrect encoding for BPF_STX BPF_B when the source operand is R10.
Signed-off-by: Xi Wang <xi.wang@gmail.com>
Signed-off-by: Luke Nelson <luke.r.nels@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200418232655.23870-2-luke.r.nels@gmail.com
When check_xadd() verifies an XADD operation on a pointer to a stack slot
containing a spilled pointer, check_stack_read() verifies that the read,
which is part of XADD, is valid. However, since the placeholder value -1 is
passed as `value_regno`, check_stack_read() can only return a binary
decision and can't return the type of the value that was read. The intent
here is to verify whether the value read from the stack slot may be used as
a SCALAR_VALUE; but since check_stack_read() doesn't check the type, and
the type information is lost when check_stack_read() returns, this is not
enforced, and a malicious user can abuse XADD to leak spilled kernel
pointers.
Fix it by letting check_stack_read() verify that the value is usable as a
SCALAR_VALUE if no type information is passed to the caller.
To be able to use __is_pointer_value() in check_stack_read(), move it up.
Fix up the expected unprivileged error message for a BPF selftest that,
until now, assumed that unprivileged users can use XADD on stack-spilled
pointers. This also gives us a test for the behavior introduced in this
patch for free.
In theory, this could also be fixed by forbidding XADD on stack spills
entirely, since XADD is a locked operation (for operations on memory with
concurrency) and there can't be any concurrency on the BPF stack; but
Alexei has said that he wants to keep XADD on stack slots working to avoid
changes to the test suite [1].
The following BPF program demonstrates how to leak a BPF map pointer as an
unprivileged user using this bug:
// r7 = map_pointer
BPF_LD_MAP_FD(BPF_REG_7, small_map),
// r8 = launder(map_pointer)
BPF_STX_MEM(BPF_DW, BPF_REG_FP, BPF_REG_7, -8),
BPF_MOV64_IMM(BPF_REG_1, 0),
((struct bpf_insn) {
.code = BPF_STX | BPF_DW | BPF_XADD,
.dst_reg = BPF_REG_FP,
.src_reg = BPF_REG_1,
.off = -8
}),
BPF_LDX_MEM(BPF_DW, BPF_REG_8, BPF_REG_FP, -8),
// store r8 into map
BPF_MOV64_REG(BPF_REG_ARG1, BPF_REG_7),
BPF_MOV64_REG(BPF_REG_ARG2, BPF_REG_FP),
BPF_ALU64_IMM(BPF_ADD, BPF_REG_ARG2, -4),
BPF_ST_MEM(BPF_W, BPF_REG_ARG2, 0, 0),
BPF_EMIT_CALL(BPF_FUNC_map_lookup_elem),
BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 1),
BPF_EXIT_INSN(),
BPF_STX_MEM(BPF_DW, BPF_REG_0, BPF_REG_8, 0),
BPF_MOV64_IMM(BPF_REG_0, 0),
BPF_EXIT_INSN()
[1] https://lore.kernel.org/bpf/20200416211116.qxqcza5vo2ddnkdq@ast-mbp.dhcp.thefacebook.com/
Fixes: 17a5267067 ("bpf: verifier (add verifier core)")
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200417000007.10734-1-jannh@google.com
Add PMTU discovery tests for these encapsulations:
- IPIP
- SIT, mode ip6ip
- ip6tnl, modes ip6ip6 and ipip6
Signed-off-by: Lourdes Pedrajas <lu@pplo.net>
Reviewed-by: Stefano Brivio <sbrivio@redhat.com>
Reviewed-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
sleepgraph:
- force usage of python3 instead of using system default
- fix bugzilla 204773 (https://bugzilla.kernel.org/show_bug.cgi?id=204773)
- fix issue of platform info not being reset in -multi (logs fill up)
- change -ftop call to "pm_suspend", this is one level below state_store
- add -wificheck command to read out the current wifi device details
- change -wifi behavior to poll /proc/net/wireless for wifi connect
- add wifi reconnect time to timeline, include time in summary column
- add "fail on wifi_resume" to timeline and summary when wifi fails
- add a set of commands to collect data before/after suspend in the log
- add "-cmdinfo" command which prints out all the data collected
- check for cmd info tools at start, print found/missing in green/red
- fix kernel suspend time calculation: tool used to look for start of
pm_suspend_console, but the order has changed. latest kernel starts
with ksys_sync, use this instead
- include time spent in mem/disk in the header (same as freeze/standby)
- ignore turbostat 32-bit capability warnings
- print to result.txt when -skiphtml is used, just say result: pass
- don't exit on SIGTSTP, it's a ctrl-Z and the tool may come back
- -multi argument supports duration as well as count: hours, minutes, seconds
- update the -multi status output to be more informative
- -maxfail sets maximum consecutive fails before a -multi run is aborted
- in -summary, ignore dmesg/ftrace/html files that are 0 size
bootgraph:
- force usage of python3 instead of using system default
README:
- add endurance testing instructions
Makefile:
- remove pycache on uninstall
Signed-off-by: Todd Brandt <todd.e.brandt@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Pull x86 and objtool fixes from Thomas Gleixner:
"A set of fixes for x86 and objtool:
objtool:
- Ignore the double UD2 which is emitted in BUG() when
CONFIG_UBSAN_TRAP is enabled.
- Support clang non-section symbols in objtool ORC dump
- Fix switch table detection in .text.unlikely
- Make the BP scratch register warning more robust.
x86:
- Increase microcode maximum patch size for AMD to cope with new CPUs
which have a larger patch size.
- Fix a crash in the resource control filesystem when the removal of
the default resource group is attempted.
- Preserve Code and Data Prioritization enabled state accross CPU
hotplug.
- Update split lock cpu matching to use the new X86_MATCH macros.
- Change the split lock enumeration as Intel finaly decided that the
IA32_CORE_CAPABILITIES bits are not architectural contrary to what
the SDM claims. !@#%$^!
- Add Tremont CPU models to the split lock detection cpu match.
- Add a missing static attribute to make sparse happy"
* tag 'x86-urgent-2020-04-19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/split_lock: Add Tremont family CPU models
x86/split_lock: Bits in IA32_CORE_CAPABILITIES are not architectural
x86/resctrl: Preserve CDP enable over CPU hotplug
x86/resctrl: Fix invalid attempt at removing the default resource group
x86/split_lock: Update to use X86_MATCH_INTEL_FAM6_MODEL()
x86/umip: Make umip_insns static
x86/microcode/AMD: Increase microcode PATCH_MAX_SIZE
objtool: Make BP scratch register warning more robust
objtool: Fix switch table detection in .text.unlikely
objtool: Support Clang non-section symbols in ORC generation
objtool: Support Clang non-section symbols in ORC dump
objtool: Fix CONFIG_UBSAN_TRAP unreachable warnings
Pull perf tooling fixes and updates from Thomas Gleixner:
- Fix the header line of perf stat output for '--metric-only --per-socket'
- Fix the python build with clang
- The usual tools UAPI header synchronization
* tag 'perf-urgent-2020-04-19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
tools headers: Synchronize linux/bits.h with the kernel sources
tools headers: Adopt verbatim copy of compiletime_assert() from kernel sources
tools headers: Update x86's syscall_64.tbl with the kernel sources
tools headers UAPI: Sync drm/i915_drm.h with the kernel sources
tools headers UAPI: Update tools's copy of drm.h headers
tools headers kvm: Sync linux/kvm.h with the kernel sources
tools headers UAPI: Sync linux/fscrypt.h with the kernel sources
tools include UAPI: Sync linux/vhost.h with the kernel sources
tools arch x86: Sync asm/cpufeatures.h with the kernel sources
tools headers UAPI: Sync linux/mman.h with the kernel
tools headers UAPI: Sync sched.h with the kernel
tools headers: Update linux/vdso.h and grab a copy of vdso/const.h
perf stat: Fix no metric header if --per-socket and --metric-only set
perf python: Check if clang supports -fno-semantic-interposition
tools arch x86: Sync the msr-index.h copy with the kernel sources
Perf checks the duplicate entries in a callchain before adding an entry.
However the check is very slow especially with deeper call stack.
Almost ~50% elapsed time of perf report is spent on the check when the
call stack is always depth of 32.
The hist_entry__cmp() is used to compare the new entry with the old
entries. It will go through all the available sorts in the sort_list,
and call the specific cmp of each sort, which is very slow.
Actually, for most cases, there are no duplicate entries in callchain.
The symbols are usually different. It's much faster to do a quick check
for symbols first. Only do the full cmp when the symbols are exactly the
same.
The quick check is only to check symbols, not dso. Export
_sort__sym_cmp.
$ perf record --call-graph lbr ./tchain_edit_64
Without the patch
$time perf report --stdio
real 0m21.142s
user 0m21.110s
sys 0m0.033s
With the patch
$time perf report --stdio
real 0m10.977s
user 0m10.948s
sys 0m0.027s
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexey Budankov <alexey.budankov@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Pavel Gerasimov <pavel.gerasimov@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Vitaly Slobodskoy <vitaly.slobodskoy@intel.com>
Link: http://lore.kernel.org/lkml/20200319202517.23423-18-kan.liang@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
In LBR call stack mode, the depth of reconstructed LBR call stack limits
to the number of LBR registers.
For example, on skylake, the depth of reconstructed LBR call stack is
always <= 32.
# To display the perf.data header info, please use
# --header/--header-only options.
#
#
# Total Lost Samples: 0
#
# Samples: 6K of event 'cycles'
# Event count (approx.): 6487119731
#
# Children Self Command Shared Object Symbol
# ........ ........ ............... ..................
# ................................
99.97% 99.97% tchain_edit tchain_edit [.] f43
|
--99.64%--f11
f12
f13
f14
f15
f16
f17
f18
f19
f20
f21
f22
f23
f24
f25
f26
f27
f28
f29
f30
f31
f32
f33
f34
f35
f36
f37
f38
f39
f40
f41
f42
f43
For a call stack which is deeper than LBR limit, HW will overwrite the
LBR register with oldest branch. Only partial call stacks can be
reconstructed.
However, the overwritten LBRs may still be retrieved from previous
sample. At that moment, HW hasn't overwritten the LBR registers yet.
Perf tools can stitch those overwritten LBRs on current call stacks to
get a more complete call stack.
To determine if LBRs can be stitched, perf tools need to compare current
sample with previous sample.
- They should have identical LBR records (Same from, to and flags
values, and the same physical index of LBR registers).
- The searching starts from the base-of-stack of current sample.
Once perf determines to stitch the previous LBRs, the corresponding LBR
cursor nodes will be copied to 'lists'. The 'lists' is to track the LBR
cursor nodes which are going to be stitched.
When the stitching is over, the nodes will not be freed immediately.
They will be moved to 'free_lists'. Next stitching may reuse the space.
Both 'lists' and 'free_lists' will be freed when all samples are
processed.
Committer notes:
Fix the intel-pt.c initialization of the union with 'struct
branch_flags', that breaks the build with its unnamed union on older gcc
versions.
Uninline thread__free_stitch_list(), as it grew big and started dragging
includes to thread.h, so move it to thread.c where what it needs in
terms of headers are already there.
This fixes the build in several systems such as debian:experimental when
cross building to the MIPS32 architecture, i.e. in the other cases what
was needed was being included by sheer luck.
In file included from builtin-sched.c:11:
util/thread.h: In function 'thread__free_stitch_list':
util/thread.h:169:3: error: implicit declaration of function 'free' [-Werror=implicit-function-declaration]
169 | free(pos);
| ^~~~
util/thread.h:169:3: error: incompatible implicit declaration of built-in function 'free' [-Werror]
util/thread.h:19:1: note: include '<stdlib.h>' or provide a declaration of 'free'
18 | #include "callchain.h"
+++ |+#include <stdlib.h>
19 |
util/thread.h:174:3: error: incompatible implicit declaration of built-in function 'free' [-Werror]
174 | free(pos);
| ^~~~
util/thread.h:174:3: note: include '<stdlib.h>' or provide a declaration of 'free'
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexey Budankov <alexey.budankov@linux.intel.com>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Pavel Gerasimov <pavel.gerasimov@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Vitaly Slobodskoy <vitaly.slobodskoy@intel.com>
Link: http://lore.kernel.org/lkml/20200319202517.23423-13-kan.liang@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
LBR only collect the user call stack. To reconstruct a call stack, both
kernel call stack and user call stack are required. The function
resolve_lbr_callchain_sample() mix the kernel call stack and user call
stack.
Now, with the help of HW idx, perf tool can reconstruct a more complete
call stack by adding some user call stack from previous sample. However,
current implementation is hard to be extended to support it.
Current code path for resolve_lbr_callchain_sample()
for (j = 0; j < mix_chain_nr; j++) {
if (ORDER_CALLEE) {
if (kernel callchain)
Fill callchain info
else if (LBR callchain)
Fill callchain info
} else {
if (LBR callchain)
Fill callchain info
else if (kernel callchain)
Fill callchain info
}
add_callchain_ip();
}
With the patch,
if (ORDER_CALLEE) {
for (j = 0; j < NUM of kernel callchain) {
Fill callchain info
add_callchain_ip();
}
for (; j < mix_chain_nr) {
Fill callchain info
add_callchain_ip();
}
} else {
for (; j < NUM of LBR callchain) {
Fill callchain info
add_callchain_ip();
}
for (j = 0; j < mix_chain_nr) {
Fill callchain info
add_callchain_ip();
}
}
No functional changes.
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexey Budankov <alexey.budankov@linux.intel.com>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Pavel Gerasimov <pavel.gerasimov@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Vitaly Slobodskoy <vitaly.slobodskoy@intel.com>
Link: http://lore.kernel.org/lkml/20200319202517.23423-7-kan.liang@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
