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a0bd7dacbd
linux/arch/s390/kernel
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Thomas Richter a0bd7dacbd s390/cpum_sf: Handle CPU hotplug remove during sampling 
CPU hotplug remove handling triggers the following function
call sequence:

   CPUHP_AP_PERF_S390_SF_ONLINE  --> s390_pmu_sf_offline_cpu()
   ...
   CPUHP_AP_PERF_ONLINE          --> perf_event_exit_cpu()

The s390 CPUMF sampling CPU hotplug handler invokes:

 s390_pmu_sf_offline_cpu()
 +-->  cpusf_pmu_setup()
       +--> setup_pmc_cpu()
            +--> deallocate_buffers()

This function de-allocates all sampling data buffers (SDBs) allocated
for that CPU at event initialization. It also clears the
PMU_F_RESERVED bit. The CPU is gone and can not be sampled.

With the event still being active on the removed CPU, the CPU event
hotplug support in kernel performance subsystem triggers the
following function calls on the removed CPU:

  perf_event_exit_cpu()
  +--> perf_event_exit_cpu_context()
       +--> __perf_event_exit_context()
	    +--> __perf_remove_from_context()
	         +--> event_sched_out()
	              +--> cpumsf_pmu_del()
	                   +--> cpumsf_pmu_stop()
                                +--> hw_perf_event_update()

to stop and remove the event. During removal of the event, the
sampling device driver tries to read out the remaining samples from
the sample data buffers (SDBs). But they have already been freed
(and may have been re-assigned). This may lead to a use after free
situation in which case the samples are most likely invalid. In the
best case the memory has not been reassigned and still contains
valid data.

Remedy this situation and check if the CPU is still in reserved
state (bit PMU_F_RESERVED set). In this case the SDBs have not been
released an contain valid data. This is always the case when
the event is removed (and no CPU hotplug off occured).
If the PMU_F_RESERVED bit is not set, the SDB buffers are gone.

Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Reviewed-by: Hendrik Brueckner <brueckner@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
2024-10-29 11:17:18 +01:00
..
syscalls syscalls: fix compat_sys_io_pgetevents_time64 usage 2024-06-25 15:57:20 +02:00
vdso32 more s390 updates for 6.10 merge window 2024-05-21 12:09:36 -07:00
vdso64 s390/vdso: Use one large alternative instead of an alternative branch 2024-09-23 17:57:04 +02:00
.gitignore
abs_lowcore.c s390: Add infrastructure to patch lowcore accesses 2024-07-23 16:02:32 +02:00
alternative.c s390: Add infrastructure to patch lowcore accesses 2024-07-23 16:02:32 +02:00
asm-offsets.c s390/entry: Unify save_area_sync and save_area_async 2024-08-29 22:56:34 +02:00
audit.c audit: add support for the openat2 syscall 2021-10-01 16:52:48 -04:00
audit.h
cache.c s390/cache: prevent rebuild of shared_cpu_list 2024-03-07 14:41:15 +01:00
cert_store.c fix missing vmalloc.h includes 2024-04-25 20:55:49 -07:00
compat_audit.c audit: add support for the openat2 syscall 2021-10-01 16:52:48 -04:00
compat_linux.c
compat_linux.h s390/compat: cleanup compat_linux.h header file 2022-05-06 20:45:16 +02:00
compat_ptrace.h
compat_signal.c s390/vdso: Move vdso symbol handling to separate header file 2024-09-13 17:28:36 +02:00
cpacf.c s390/crypto: Display Query and Query Authentication Information in sysfs 2024-09-12 14:13:27 +02:00
cpcmd.c s390: include linux/io.h instead of asm/io.h 2023-07-03 11:19:40 +02:00
cpufeature.c s390/uvdevice: autoload module based on CPU facility 2022-07-19 16:18:49 +02:00
crash_dump.c s390/kdump: Provide is_kdump_kernel() implementation 2024-10-25 16:03:23 +02:00
ctlreg.c s390/ctlreg: add system_ctl_load() 2023-09-19 13:26:57 +02:00
debug.c s390: Fix various typos 2024-10-25 16:03:23 +02:00
diag.c s390/wti: Introduce infrastructure for warning track interrupt 2024-08-29 22:56:34 +02:00
dis.c s390/disassembler: Remove duplicate instruction format RSY_RDRU 2024-09-12 14:13:27 +02:00
dumpstack.c s390: Replace S390_lowcore by get_lowcore() 2024-06-18 17:01:33 +02:00
early_printk.c s390/early: Dump register contents and call trace for early crashes 2024-08-22 19:28:11 +02:00
early.c s390/setup: Recognize sequential instruction fetching facility 2024-08-29 22:56:34 +02:00
ebcdic.c s390/ebcdic: fix typo in comment 2023-07-27 13:11:35 +02:00
entry.h s390/switch_to: use generic header file 2024-02-12 15:03:33 +01:00
entry.S s390 updates for 6.12 merge window 2024-09-21 09:02:54 -07:00
facility.c KVM: s390: vsie: Fix length of facility list shadowed 2023-12-23 10:41:09 +01:00
fpu.c s390/fpu: Re-add exception handling in load_fpu_state() 2024-07-31 16:30:20 +02:00
ftrace.c s390/ftrace: Avoid extra serialization for graph caller patching 2024-08-29 22:56:34 +02:00
ftrace.h s390/ftrace: Remove unused ftrace_plt_template* 2024-08-27 20:16:48 +02:00
guarded_storage.c s390: use control register bit defines 2023-09-19 13:26:57 +02:00
head64.S s390/head64: Make startup code ready for lowcore relocation 2024-07-23 16:02:32 +02:00
hiperdispatch.c s390/hiperdispatch: Add hiperdispatch debug counters 2024-08-29 22:56:35 +02:00
idle.c s390/idle: Remove duplicate get_lowcore() calls 2024-06-18 17:01:33 +02:00
ima_arch.c
ipl_vmparm.c
ipl.c s390/ipl: Switch over to sysfs_emit() 2024-10-25 16:03:24 +02:00
irq.c s390/wti: Introduce infrastructure for warning track interrupt 2024-08-29 22:56:34 +02:00
jump_label.c jump_label: make initial NOP patching the special case 2022-06-24 09:48:55 +02:00
kdebugfs.c
kexec_elf.c s390, crash: wrap crash dumping code into crash related ifdefs 2024-02-23 17:48:23 -08:00
kexec_image.c s390, crash: wrap crash dumping code into crash related ifdefs 2024-02-23 17:48:23 -08:00
kprobes.c s390/kprobes: Avoid stop machine if possible 2024-08-29 22:56:34 +02:00
lgr.c s390/lgr: use simple assignment instead of memcpy 2022-02-06 23:31:29 +01:00
machine_kexec_file.c s390, crash: wrap crash dumping code into crash related ifdefs 2024-02-23 17:48:23 -08:00
machine_kexec_reloc.c
machine_kexec.c s390/kdump: Make kdump ready for lowcore relocation 2024-07-23 16:02:32 +02:00
Makefile s390/crypto: Display Query and Query Authentication Information in sysfs 2024-09-12 14:13:27 +02:00
mcount.S s390: Use MARCH_HAS_*_FEATURES defines 2024-09-07 17:12:42 +02:00
module.c arch: make execmem setup available regardless of CONFIG_MODULES 2024-05-14 00:31:44 -07:00
nmi.c s390/nmi: Remove duplicate get_lowcore() calls 2024-06-18 17:01:33 +02:00
nospec-branch.c s390/nospec: Push down alternative handling 2024-07-23 16:02:31 +02:00
nospec-sysfs.c s390/nospec: Switch over to sysfs_emit() 2024-10-25 16:03:24 +02:00
numa.c arch, mm: move definition of node_data to generic code 2024-09-03 21:15:28 -07:00
os_info.c s390: Fix various typos 2024-10-25 16:03:23 +02:00
perf_cpum_cf_events.c s390/cpum_cf: make crypto counters upward compatible across machine types 2024-04-09 17:29:56 +02:00
perf_cpum_cf.c s390: Fix various typos 2024-10-25 16:03:23 +02:00
perf_cpum_sf.c s390/cpum_sf: Handle CPU hotplug remove during sampling 2024-10-29 11:17:18 +01:00
perf_event.c s390/perf_event: Switch over to sysfs_emit() 2024-10-25 16:03:24 +02:00
perf_pai_crypto.c s390/pai_crypto: Add support for MSA 10 and 11 pai counters 2024-09-05 15:17:23 +02:00
perf_pai_ext.c s390/pai_ext: Update PAI extension 1 counters 2024-09-05 15:17:23 +02:00
perf_regs.c s390/fpu: remove anonymous union from struct fpu 2024-02-16 14:30:16 +01:00
process.c s390: Replace S390_lowcore by get_lowcore() 2024-06-18 17:01:33 +02:00
processor.c s390/alternatives: Move text sync functions 2024-07-23 16:02:31 +02:00
ptrace.c s390/fpu: remove anonymous union from struct fpu 2024-02-16 14:30:16 +01:00
reipl.S s390/kdump: Make kdump ready for lowcore relocation 2024-07-23 16:02:32 +02:00
relocate_kernel.S s390/relocate_kernel: adjust indentation 2023-04-19 17:24:18 +02:00
rethook.c s390/rethook: add local rethook header file 2023-02-06 11:13:53 +01:00
rethook.h s390/rethook: add local rethook header file 2023-02-06 11:13:53 +01:00
runtime_instr.c
setup.c s390/mm: Prevent lowcore vs identity mapping overlap 2024-08-21 16:14:45 +02:00
signal.c s390/vdso: Move vdso symbol handling to separate header file 2024-09-13 17:28:36 +02:00
smp.c s390/smp: Switch over to sysfs_emit() 2024-10-25 16:03:24 +02:00
stacktrace.c s390/ftrace: Avoid calling unwinder in ftrace_return_address() 2024-08-27 20:16:48 +02:00
sthyi.c s390/sthyi: Use cached data when diag is busy 2024-07-10 19:50:45 +02:00
syscall.c s390 updates for 6.11 merge window 2024-07-18 15:41:45 -07:00
sysinfo.c [tree-wide] finally take no_llseek out 2024-09-27 08:18:43 -07:00
text_amode31.S s390/hypfs_diag0c: fix virtual vs physical address confusion 2024-02-09 13:58:13 +01:00
time.c s390/time: Switch over to sysfs_emit() 2024-10-25 16:03:23 +02:00
topology.c s390/topology: Switch over to sysfs_emit() 2024-10-25 16:03:23 +02:00
trace.c
traps.c - 875fa64577 ("mm/hugetlb_vmemmap: fix race with speculative PFN 2024-07-21 17:15:46 -07:00
unwind_bc.c s390/unwind: disable KMSAN checks 2024-07-03 19:30:25 -07:00
uprobes.c s390/switch_to: use generic header file 2024-02-12 15:03:33 +01:00
uv.c s390/uv: Retrieve UV secrets sysfs support 2024-10-29 11:17:17 +01:00
vdso.c s390/vdso: Wire up getrandom() vdso implementation 2024-09-13 20:57:31 +02:00
vmcore_info.c s390/vmcoreinfo: Store virtual memory layout 2024-04-17 13:38:01 +02:00
vmlinux.lds.S asm-generic updates for 6.12 2024-09-26 11:54:40 -07:00
vtime.c s390/vtime: Remove duplicate get_lowcore() calls 2024-06-18 17:01:33 +02:00
wti.c s390/wti: Add debugfs file to display missed grace periods per cpu 2024-08-29 22:56:35 +02:00