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cbbf2e6ed7
linux/arch/arm64/kernel
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Daniel Thompson cbbf2e6ed7 arm64: perf: Prevent wraparound during overflow 
If the overflow threshold for a counter is set above or near the
0xffffffff boundary then the kernel may lose track of the overflow
causing only events that occur *after* the overflow to be recorded.
Specifically the problem occurs when the value of the performance counter
overtakes its original programmed value due to wrap around.

Typical solutions to this problem are either to avoid programming in
values likely to be overtaken or to treat the overflow bit as the 33rd
bit of the counter.

Its somewhat fiddly to refactor the code to correctly handle the 33rd bit
during irqsave sections (context switches for example) so instead we take
the simpler approach of avoiding values likely to be overtaken.

We set the limit to half of max_period because this matches the limit
imposed in __hw_perf_event_init(). This causes a doubling of the interrupt
rate for large threshold values, however even with a very fast counter
ticking at 4GHz the interrupt rate would only be ~1Hz.

Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
2014-12-04 10:26:54 +00:00
..
vdso arm64: vdso: fix build error when switching from LE to BE 2014-07-30 15:06:35 +01:00
.gitignore arm64: Build infrastructure 2012-09-17 13:42:21 +01:00
alternative.c arm64: add alternative runtime patching 2014-11-25 13:46:36 +00:00
arm64ksyms.c arm64: Add ftrace support 2014-05-29 09:08:08 +01:00
armv8_deprecated.c arm64: fix return code check when changing emulation handler 2014-11-25 10:05:35 +00:00
asm-offsets.c arm64: KVM: implement lazy world switch for debug registers 2014-07-11 04:57:46 -07:00
cpu_errata.c arm64: alternatives: fix pr_fmt string for consistency 2014-11-25 18:27:01 +00:00
cpu_ops.c arm64: kernel: enable PSCI cpu operations on UP systems 2014-07-18 15:23:25 +01:00
cpuidle.c arm64: kernel: introduce cpu_init_idle CPU operation 2014-09-12 10:48:55 +01:00
cpuinfo.c arm64: sanity checks: add ID_AA64DFR{0,1}_EL1 2014-11-25 15:56:44 +00:00
cputable.c arm64: add CPU_HOTPLUG infrastructure 2013-10-25 11:33:21 +01:00
debug-monitors.c KVM/ARM New features for 3.17 include: 2014-08-05 09:47:45 +02:00
efi-entry.S arm64/efi: efistub: jump to 'stext' directly, not through the header 2014-11-05 09:02:59 +01:00
efi-stub.c arm64/efi: efistub: don't abort if base of DRAM is occupied 2014-09-08 14:39:18 +01:00
efi.c arm64: dmi: set DMI string as dump stack arch description 2014-11-05 09:03:32 +01:00
entry-fpsimd.S arm64: fpsimd: fix a typo in fpsimd_save_partial_state ENDPROC 2014-07-31 11:42:42 +01:00
entry-ftrace.S arm64: ftrace: eliminate literal pool entries 2014-11-07 15:04:49 +00:00
entry.S arm64: ptrace: allow tracer to skip a system call 2014-11-28 10:24:13 +00:00
fpsimd.c arm64: fix bug for reloading FPSIMD state after cpu power off 2014-09-01 12:55:21 +01:00
ftrace.c arm64: Correct ftrace calls to aarch64_insn_gen_branch_imm() 2014-09-19 12:05:45 +01:00
head.S arm64: Move some head.text functions to executable section 2014-11-26 17:19:47 +00:00
hw_breakpoint.c arm64: is_compat_task is defined both in asm/compat.h and linux/compat.h 2014-05-12 16:43:29 +01:00
hyp-stub.S irqchip: gic-v3: Initial support for GICv3 2014-07-08 22:11:47 +00:00
image.h arm64: Update the Image header 2014-07-10 12:36:40 +01:00
insn.c arm64: Emulate CP15 Barrier instructions 2014-11-20 16:34:48 +00:00
io.c arm64: optimize memcpy_{from,to}io() and memset_io() 2014-11-06 17:25:27 +00:00
irq.c arm64: Treat handle_arch_irq as a function pointer 2014-11-25 15:56:44 +00:00
jump_label.c arm64: jump labels: NOP out NOP -> NOP replacement 2014-11-26 17:19:47 +00:00
kgdb.c arm64: Fix typos in KGDB macros 2014-09-25 15:35:41 +01:00
kuser32.S arm64: Add __NR_* definitions for compat syscalls 2014-07-10 11:02:40 +01:00
Makefile arm64: detect silicon revisions and set cap bits accordingly 2014-11-25 13:46:37 +00:00
module.c arm64: move encode_insn_immediate() from module.c to insn.c 2014-01-08 15:21:29 +00:00
pci.c arm64: Add architectural support for PCI 2014-09-30 17:08:57 -06:00
perf_event.c arm64: perf: Prevent wraparound during overflow 2014-12-04 10:26:54 +00:00
perf_regs.c arm64: perf: don't rely on layout of pt_regs when grabbing sp or pc 2014-08-28 20:01:50 +01:00
process.c arm64: ASLR: Don't randomise text when randomise_va_space == 0 2014-10-24 15:47:49 +01:00
psci.c arm64: add PSCI CPU_SUSPEND based cpu_suspend support 2014-09-12 10:48:56 +01:00
ptrace.c arm64: add seccomp support 2014-11-28 10:24:59 +00:00
return_address.c arm64: LLVMLinux: Use global stack pointer in return_address() 2014-09-08 14:39:19 +01:00
setup.c arm64: Provide a namespace to NCAPS 2014-12-04 09:57:41 +00:00
signal32.c arm64: add SIGSYS siginfo for compat task 2014-11-28 10:24:59 +00:00
signal.c arm64: Use sigsp() 2014-08-06 13:03:45 +02:00
sleep.S arm64: Move cpu_resume into the text section 2014-11-25 15:56:44 +00:00
smp_spin_table.c arm64: spin-table: handle unmapped cpu-release-addrs 2014-09-08 14:39:18 +01:00
smp.c arm64: add alternative runtime patching 2014-11-25 13:46:36 +00:00
stacktrace.c arm64: LLVMLinux: Use current_stack_pointer in save_stack_trace_tsk 2014-09-08 14:39:19 +01:00
suspend.c arm64: Move cpu_resume into the text section 2014-11-25 15:56:44 +00:00
sys32.S arm64: compat: correct register concatenation for syscall wrappers 2013-10-25 15:59:36 +01:00
sys_compat.c arm64: compat: align cacheflush syscall with arch/arm 2014-12-01 13:31:12 +00:00
sys.c arm64: switch to generic sigaltstack 2013-02-14 09:17:29 -05:00
time.c arm64: kernel: initialize broadcast hrtimer based clock event device 2014-05-30 17:48:13 +01:00
topology.c arm64: topology: Fix handling of multi-level cluster MPIDR-based detection 2014-11-25 15:56:43 +00:00
trace-events-emulation.h arm64: Trace emulation of AArch32 legacy instructions 2014-11-20 16:35:02 +00:00
traps.c arm64: Add support for hooks to handle undefined instructions 2014-11-20 16:33:43 +00:00
vdso.c arm64,ia64,ppc,s390,sh,tile,um,x86,mm: remove default gate area 2014-08-08 15:57:27 -07:00
vmlinux.lds.S arm64: vmlinux.lds.S: don't discard .exit.* sections at link-time 2014-11-25 15:56:45 +00:00