1# 2# General architecture dependent options 3# 4 5config OPROFILE 6 tristate "OProfile system profiling" 7 depends on PROFILING 8 depends on HAVE_OPROFILE 9 select RING_BUFFER 10 select RING_BUFFER_ALLOW_SWAP 11 help 12 OProfile is a profiling system capable of profiling the 13 whole system, include the kernel, kernel modules, libraries, 14 and applications. 15 16 If unsure, say N. 17 18config OPROFILE_EVENT_MULTIPLEX 19 bool "OProfile multiplexing support (EXPERIMENTAL)" 20 default n 21 depends on OPROFILE && X86 22 help 23 The number of hardware counters is limited. The multiplexing 24 feature enables OProfile to gather more events than counters 25 are provided by the hardware. This is realized by switching 26 between events at an user specified time interval. 27 28 If unsure, say N. 29 30config HAVE_OPROFILE 31 bool 32 33config OPROFILE_NMI_TIMER 34 def_bool y 35 depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI 36 37config KPROBES 38 bool "Kprobes" 39 depends on MODULES 40 depends on HAVE_KPROBES 41 select KALLSYMS 42 help 43 Kprobes allows you to trap at almost any kernel address and 44 execute a callback function. register_kprobe() establishes 45 a probepoint and specifies the callback. Kprobes is useful 46 for kernel debugging, non-intrusive instrumentation and testing. 47 If in doubt, say "N". 48 49config JUMP_LABEL 50 bool "Optimize very unlikely/likely branches" 51 depends on HAVE_ARCH_JUMP_LABEL 52 help 53 This option enables a transparent branch optimization that 54 makes certain almost-always-true or almost-always-false branch 55 conditions even cheaper to execute within the kernel. 56 57 Certain performance-sensitive kernel code, such as trace points, 58 scheduler functionality, networking code and KVM have such 59 branches and include support for this optimization technique. 60 61 If it is detected that the compiler has support for "asm goto", 62 the kernel will compile such branches with just a nop 63 instruction. When the condition flag is toggled to true, the 64 nop will be converted to a jump instruction to execute the 65 conditional block of instructions. 66 67 This technique lowers overhead and stress on the branch prediction 68 of the processor and generally makes the kernel faster. The update 69 of the condition is slower, but those are always very rare. 70 71 ( On 32-bit x86, the necessary options added to the compiler 72 flags may increase the size of the kernel slightly. ) 73 74config OPTPROBES 75 def_bool y 76 depends on KPROBES && HAVE_OPTPROBES 77 depends on !PREEMPT 78 79config HAVE_EFFICIENT_UNALIGNED_ACCESS 80 bool 81 help 82 Some architectures are unable to perform unaligned accesses 83 without the use of get_unaligned/put_unaligned. Others are 84 unable to perform such accesses efficiently (e.g. trap on 85 unaligned access and require fixing it up in the exception 86 handler.) 87 88 This symbol should be selected by an architecture if it can 89 perform unaligned accesses efficiently to allow different 90 code paths to be selected for these cases. Some network 91 drivers, for example, could opt to not fix up alignment 92 problems with received packets if doing so would not help 93 much. 94 95 See Documentation/unaligned-memory-access.txt for more 96 information on the topic of unaligned memory accesses. 97 98config HAVE_SYSCALL_WRAPPERS 99 bool 100 101config KRETPROBES 102 def_bool y 103 depends on KPROBES && HAVE_KRETPROBES 104 105config USER_RETURN_NOTIFIER 106 bool 107 depends on HAVE_USER_RETURN_NOTIFIER 108 help 109 Provide a kernel-internal notification when a cpu is about to 110 switch to user mode. 111 112config HAVE_IOREMAP_PROT 113 bool 114 115config HAVE_KPROBES 116 bool 117 118config HAVE_KRETPROBES 119 bool 120 121config HAVE_OPTPROBES 122 bool 123 124config HAVE_NMI_WATCHDOG 125 bool 126# 127# An arch should select this if it provides all these things: 128# 129# task_pt_regs() in asm/processor.h or asm/ptrace.h 130# arch_has_single_step() if there is hardware single-step support 131# arch_has_block_step() if there is hardware block-step support 132# asm/syscall.h supplying asm-generic/syscall.h interface 133# linux/regset.h user_regset interfaces 134# CORE_DUMP_USE_REGSET #define'd in linux/elf.h 135# TIF_SYSCALL_TRACE calls tracehook_report_syscall_{entry,exit} 136# TIF_NOTIFY_RESUME calls tracehook_notify_resume() 137# signal delivery calls tracehook_signal_handler() 138# 139config HAVE_ARCH_TRACEHOOK 140 bool 141 142config HAVE_DMA_ATTRS 143 bool 144 145config USE_GENERIC_SMP_HELPERS 146 bool 147 148config HAVE_REGS_AND_STACK_ACCESS_API 149 bool 150 help 151 This symbol should be selected by an architecure if it supports 152 the API needed to access registers and stack entries from pt_regs, 153 declared in asm/ptrace.h 154 For example the kprobes-based event tracer needs this API. 155 156config HAVE_CLK 157 bool 158 help 159 The <linux/clk.h> calls support software clock gating and 160 thus are a key power management tool on many systems. 161 162config HAVE_DMA_API_DEBUG 163 bool 164 165config HAVE_HW_BREAKPOINT 166 bool 167 depends on PERF_EVENTS 168 169config HAVE_MIXED_BREAKPOINTS_REGS 170 bool 171 depends on HAVE_HW_BREAKPOINT 172 help 173 Depending on the arch implementation of hardware breakpoints, 174 some of them have separate registers for data and instruction 175 breakpoints addresses, others have mixed registers to store 176 them but define the access type in a control register. 177 Select this option if your arch implements breakpoints under the 178 latter fashion. 179 180config HAVE_USER_RETURN_NOTIFIER 181 bool 182 183config HAVE_PERF_EVENTS_NMI 184 bool 185 help 186 System hardware can generate an NMI using the perf event 187 subsystem. Also has support for calculating CPU cycle events 188 to determine how many clock cycles in a given period. 189 190config HAVE_ARCH_JUMP_LABEL 191 bool 192 193config HAVE_ARCH_MUTEX_CPU_RELAX 194 bool 195 196config HAVE_RCU_TABLE_FREE 197 bool 198 199config ARCH_HAVE_NMI_SAFE_CMPXCHG 200 bool 201 202config HAVE_ALIGNED_STRUCT_PAGE 203 bool 204 help 205 This makes sure that struct pages are double word aligned and that 206 e.g. the SLUB allocator can perform double word atomic operations 207 on a struct page for better performance. However selecting this 208 might increase the size of a struct page by a word. 209 210config HAVE_CMPXCHG_LOCAL 211 bool 212 213config HAVE_CMPXCHG_DOUBLE 214 bool 215 216config ARCH_WANT_OLD_COMPAT_IPC 217 bool 218 219config HAVE_ARCH_SECCOMP_FILTER 220 bool 221 help 222 An arch should select this symbol if it provides all of these things: 223 - syscall_get_arch() 224 - syscall_get_arguments() 225 - syscall_rollback() 226 - syscall_set_return_value() 227 - SIGSYS siginfo_t support 228 - secure_computing is called from a ptrace_event()-safe context 229 - secure_computing return value is checked and a return value of -1 230 results in the system call being skipped immediately. 231 - seccomp syscall wired up 232 233config SECCOMP_FILTER 234 def_bool y 235 depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET 236 help 237 Enable tasks to build secure computing environments defined 238 in terms of Berkeley Packet Filter programs which implement 239 task-defined system call filtering polices. 240 241 See Documentation/prctl/seccomp_filter.txt for details. 242 243config HAVE_ARCH_MMAP_RND_BITS 244 bool 245 help 246 An arch should select this symbol if it supports setting a variable 247 number of bits for use in establishing the base address for mmap 248 allocations, has MMU enabled and provides values for both: 249 - ARCH_MMAP_RND_BITS_MIN 250 - ARCH_MMAP_RND_BITS_MAX 251 252config ARCH_MMAP_RND_BITS_MIN 253 int 254 255config ARCH_MMAP_RND_BITS_MAX 256 int 257 258config ARCH_MMAP_RND_BITS_DEFAULT 259 int 260 261config ARCH_MMAP_RND_BITS 262 int "Number of bits to use for ASLR of mmap base address" if EXPERT 263 range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX 264 default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT 265 default ARCH_MMAP_RND_BITS_MIN 266 depends on HAVE_ARCH_MMAP_RND_BITS 267 help 268 This value can be used to select the number of bits to use to 269 determine the random offset to the base address of vma regions 270 resulting from mmap allocations. This value will be bounded 271 by the architecture's minimum and maximum supported values. 272 273 This value can be changed after boot using the 274 /proc/sys/vm/mmap_rnd_bits tunable 275 276config HAVE_ARCH_MMAP_RND_COMPAT_BITS 277 bool 278 help 279 An arch should select this symbol if it supports running applications 280 in compatibility mode, supports setting a variable number of bits for 281 use in establishing the base address for mmap allocations, has MMU 282 enabled and provides values for both: 283 - ARCH_MMAP_RND_COMPAT_BITS_MIN 284 - ARCH_MMAP_RND_COMPAT_BITS_MAX 285 286config ARCH_MMAP_RND_COMPAT_BITS_MIN 287 int 288 289config ARCH_MMAP_RND_COMPAT_BITS_MAX 290 int 291 292config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 293 int 294 295config ARCH_MMAP_RND_COMPAT_BITS 296 int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT 297 range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX 298 default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 299 default ARCH_MMAP_RND_COMPAT_BITS_MIN 300 depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS 301 help 302 This value can be used to select the number of bits to use to 303 determine the random offset to the base address of vma regions 304 resulting from mmap allocations for compatible applications This 305 value will be bounded by the architecture's minimum and maximum 306 supported values. 307 308 This value can be changed after boot using the 309 /proc/sys/vm/mmap_rnd_compat_bits tunable 310 311source "kernel/gcov/Kconfig" 312