static volatile sig_atomic_t stop;
- static void sighandler (int signr)
+ static void sighandler(int signr)
{
- (void) signr;
- stop = 1;
+ (void) signr;
+ stop = 1;
}
+
static unsigned long hog (unsigned long niters)
{
- stop = 0;
- while (!stop && --niters);
- return niters;
+ stop = 0;
+ while (!stop && --niters);
+ return niters;
}
+
int main (void)
{
- int i;
- struct itimerval it = { .it_interval = { .tv_sec = 0, .tv_usec = 1 },
- .it_value = { .tv_sec = 0, .tv_usec = 1 } };
- sigset_t set;
- unsigned long v[HIST];
- double tmp = 0.0;
- unsigned long n;
- signal (SIGALRM, &sighandler);
- setitimer (ITIMER_REAL, &it, NULL);
-
- hog (ULONG_MAX);
- for (i = 0; i < HIST; ++i) v[i] = ULONG_MAX - hog (ULONG_MAX);
- for (i = 0; i < HIST; ++i) tmp += v[i];
- tmp /= HIST;
- n = tmp - (tmp / 3.0);
-
- sigemptyset (&set);
- sigaddset (&set, SIGALRM);
-
- for (;;) {
- hog (n);
- sigwait (&set, &i);
- }
- return 0;
+ int i;
+ struct itimerval it = {
+ .it_interval = { .tv_sec = 0, .tv_usec = 1 },
+ .it_value = { .tv_sec = 0, .tv_usec = 1 } };
+ sigset_t set;
+ unsigned long v[HIST];
+ double tmp = 0.0;
+ unsigned long n;
+ signal(SIGALRM, &sighandler);
+ setitimer(ITIMER_REAL, &it, NULL);
+
+ hog (ULONG_MAX);
+ for (i = 0; i < HIST; ++i) v[i] = ULONG_MAX - hog(ULONG_MAX);
+ for (i = 0; i < HIST; ++i) tmp += v[i];
+ tmp /= HIST;
+ n = tmp - (tmp / 3.0);
+
+ sigemptyset(&set);
+ sigaddset(&set, SIGALRM);
+
+ for (;;) {
+ hog(n);
+ sigwait(&set, &i);
+ }
+ return 0;
}
- admin_reserve_kbytes
- block_dump
- compact_memory
+- compaction_proactiveness
- compact_unevictable_allowed
- dirty_background_bytes
- dirty_background_ratio
- dirty_writeback_centisecs
- drop_caches
- extfrag_threshold
+- highmem_is_dirtyable
- hugetlb_shm_group
- laptop_mode
- legacy_va_layout
+.. _hugetlbpage_index:
+
====================
HugeTLBpage on ARM64
====================
console
dcdbas
eisa
- ipmb
isa
isapnp
io-mapping
-===============
-Provoke crashes
-===============
+.. SPDX-License-Identifier: GPL-2.0
-The lkdtm module provides an interface to crash or injure the kernel at
-predefined crashpoints to evaluate the reliability of crash dumps obtained
-using different dumping solutions. The module uses KPROBEs to instrument
-crashing points, but can also crash the kernel directly without KRPOBE
-support.
+============================================================
+Provoking crashes with Linux Kernel Dump Test Module (LKDTM)
+============================================================
+The lkdtm module provides an interface to disrupt (and usually crash)
+the kernel at predefined code locations to evaluate the reliability of
+the kernel's exception handling and to test crash dumps obtained using
+different dumping solutions. The module uses KPROBEs to instrument the
+trigger location, but can also trigger the kernel directly without KPROBE
+support via debugfs.
-You can provide the way either through module arguments when inserting
-the module, or through a debugfs interface.
+You can select the location of the trigger ("crash point name") and the
+type of action ("crash point type") either through module arguments when
+inserting the module, or through the debugfs interface.
Usage::
[cpoint_count={>0}]
recur_count
- Recursion level for the stack overflow test. Default is 10.
+ Recursion level for the stack overflow test. By default this is
+ dynamically calculated based on kernel configuration, with the
+ goal of being just large enough to exhaust the kernel stack. The
+ value can be seen at `/sys/module/lkdtm/parameters/recur_count`.
cpoint_name
- Crash point where the kernel is to be crashed. It can be
+ Where in the kernel to trigger the action. It can be
one of INT_HARDWARE_ENTRY, INT_HW_IRQ_EN, INT_TASKLET_ENTRY,
FS_DEVRW, MEM_SWAPOUT, TIMERADD, SCSI_DISPATCH_CMD,
- IDE_CORE_CP, DIRECT
+ IDE_CORE_CP, or DIRECT
cpoint_type
Indicates the action to be taken on hitting the crash point.
- It can be one of PANIC, BUG, EXCEPTION, LOOP, OVERFLOW,
- CORRUPT_STACK, UNALIGNED_LOAD_STORE_WRITE, OVERWRITE_ALLOCATION,
- WRITE_AFTER_FREE,
+ These are numerous, and best queried directly from debugfs. Some
+ of the common ones are PANIC, BUG, EXCEPTION, LOOP, and OVERFLOW.
+ See the contents of `/sys/kernel/debug/provoke-crash/DIRECT` for
+ a complete list.
cpoint_count
Indicates the number of times the crash point is to be hit
- to trigger an action. The default is 10.
+ before triggering the action. The default is 10 (except for
+ DIRECT, which always fires immediately).
You can also induce failures by mounting debugfs and writing the type to
-<mountpoint>/provoke-crash/<crashpoint>. E.g.::
+<debugfs>/provoke-crash/<crashpoint>. E.g.::
- mount -t debugfs debugfs /mnt
- echo EXCEPTION > /mnt/provoke-crash/INT_HARDWARE_ENTRY
+ mount -t debugfs debugfs /sys/kernel/debug
+ echo EXCEPTION > /sys/kernel/debug/provoke-crash/INT_HARDWARE_ENTRY
+The special file `DIRECT` will induce the action directly without KPROBE
+instrumentation. This mode is the only one available when the module is
+built for a kernel without KPROBEs support::
-A special file is `DIRECT` which will induce the crash directly without
-KPROBE instrumentation. This mode is the only one available when the module
-is built on a kernel without KPROBEs support.
+ # Instead of having a BUG kill your shell, have it kill "cat":
+ cat <(echo WRITE_RO) >/sys/kernel/debug/provoke-crash/DIRECT
strcpy()
--------
-strcpy() performs no bounds checking on the destination
-buffer. This could result in linear overflows beyond the
-end of the buffer, leading to all kinds of misbehaviors. While
-`CONFIG_FORTIFY_SOURCE=y` and various compiler flags help reduce the
-risk of using this function, there is no good reason to add new uses of
-this function. The safe replacement is strscpy().
+strcpy() performs no bounds checking on the destination buffer. This
+could result in linear overflows beyond the end of the buffer, leading to
+all kinds of misbehaviors. While `CONFIG_FORTIFY_SOURCE=y` and various
+compiler flags help reduce the risk of using this function, there is
+no good reason to add new uses of this function. The safe replacement
+is strscpy(), though care must be given to any cases where the return
+value of strcpy() was used, since strscpy() does not return a pointer to
+the destination, but rather a count of non-NUL bytes copied (or negative
+errno when it truncates).
strncpy() on NUL-terminated strings
-----------------------------------
-Use of strncpy() does not guarantee that the destination buffer
-will be NUL terminated. This can lead to various linear read overflows
-and other misbehavior due to the missing termination. It also NUL-pads the
-destination buffer if the source contents are shorter than the destination
-buffer size, which may be a needless performance penalty for callers using
-only NUL-terminated strings. The safe replacement is strscpy().
-(Users of strscpy() still needing NUL-padding should instead
-use strscpy_pad().)
+Use of strncpy() does not guarantee that the destination buffer will
+be NUL terminated. This can lead to various linear read overflows and
+other misbehavior due to the missing termination. It also NUL-pads
+the destination buffer if the source contents are shorter than the
+destination buffer size, which may be a needless performance penalty
+for callers using only NUL-terminated strings. The safe replacement is
+strscpy(), though care must be given to any cases where the return value
+of strncpy() was used, since strscpy() does not return a pointer to the
+destination, but rather a count of non-NUL bytes copied (or negative
+errno when it truncates). Any cases still needing NUL-padding should
+instead use strscpy_pad().
If a caller is using non-NUL-terminated strings, strncpy() can
still be used, but destinations should be marked with the `__nonstring
strlcpy()
---------
-strlcpy() reads the entire source buffer first, possibly exceeding
-the given limit of bytes to copy. This is inefficient and can lead to
-linear read overflows if a source string is not NUL-terminated. The
-safe replacement is strscpy().
+strlcpy() reads the entire source buffer first (since the return value
+is meant to match that of strlen()). This read may exceed the destination
+size limit. This is both inefficient and can lead to linear read overflows
+if a source string is not NUL-terminated. The safe replacement is strscpy(),
+though care must be given to any cases where the return value of strlcpy()
+is used, since strscpy() will return negative errno values when it truncates.
%p format specifier
-------------------
understand the subject area and to perform thorough reviews, will normally
increase the likelihood of your patch getting into the kernel.
+Both Tested-by and Reviewed-by tags, once received on mailing list from tester
+or reviewer, should be added by author to the applicable patches when sending
+next versions. However if the patch has changed substantially in following
+version, these tags might not be applicable anymore and thus should be removed.
+Usually removal of someone's Tested-by or Reviewed-by tags should be mentioned
+in the patch changelog (after the '---' separator).
+
A Suggested-by: tag indicates that the patch idea is suggested by the person
named and ensures credit to the person for the idea. Please note that this
tag should not be added without the reporter's permission, especially if the
--- /dev/null
+.. include:: ../disclaimer-zh_CN.rst
+
+:Original: :ref:`Documentation/arm64/hugetlbpage.rst <hugetlbpage_index>`
+
+Translator: Bailu Lin <bailu.lin@vivo.com>
+
+=====================
+ARM64中的 HugeTLBpage
+=====================
+
+大页依靠有效利用 TLBs 来提高地址翻译的性能。这取决于以下
+两点 -
+
+ - 大页的大小
+ - TLBs 支持的条目大小
+
+ARM64 接口支持2种大页方式。
+
+1) pud/pmd 级别的块映射
+-----------------------
+
+这是常规大页，他们的 pmd 或 pud 页面表条目指向一个内存块。
+不管 TLB 中支持的条目大小如何，块映射可以减少翻译大页地址
+所需遍历的页表深度。
+
+2) 使用连续位
+-------------
+
+架构中转换页表条目(D4.5.3, ARM DDI 0487C.a)中提供一个连续
+位告诉 MMU 这个条目是一个连续条目集的一员，它可以被缓存在单
+个 TLB 条目中。
+
+在 Linux 中连续位用来增加 pmd 和 pte(最后一级)级别映射的大
+小。受支持的连续页表条目数量因页面大小和页表级别而异。
+
+
+支持以下大页尺寸配置 -
+
+ ====== ======== ==== ======== ===
+ - CONT PTE PMD CONT PMD PUD
+ ====== ======== ==== ======== ===
+ 4K: 64K 2M 32M 1G
+ 16K: 2M 32M 1G
+ 64K: 2M 512M 16G
+ ====== ======== ==== ======== ===
:maxdepth: 2
amu
+ hugetlbpage
So here because at time N+2 the clear page table entry was not pair with a
notification to invalidate the secondary TLB, the device see the new value for
-addrB before seing the new value for addrA. This break total memory ordering
+addrB before seeing the new value for addrA. This break total memory ordering
for the device.
When changing a pte to write protect or to point to a new write protected page
2. Ensure that writeback is complete.
3. Lock the new page that we want to move to. It is locked so that accesses to
- this (not yet uptodate) page immediately block while the move is in progress.
+ this (not yet up-to-date) page immediately block while the move is in progress.
4. All the page table references to the page are converted to migration
entries. This decreases the mapcount of a page. If the resulting
using it for analyzing who allocate each page is rather complex. We need
to enlarge the trace buffer for preventing overlapping until userspace
program launched. And, launched program continually dump out the trace
-buffer for later analysis and it would change system behviour with more
+buffer for later analysis and it would change system behaviour with more
possibility rather than just keeping it in memory, so bad for debugging.
page owner can also be used for various purposes. For example, accurate
can go unnoticed. To deal with that, ``slabinfo-gnuplot.sh`` has two
options to 'zoom-in'/'zoom-out':
- a) ``-s %d,%d`` -- overwrites the default image width and heigh
+ a) ``-s %d,%d`` -- overwrites the default image width and height
b) ``-r %d,%d`` -- specifies a range of samples to use (for example,
in ``slabinfo -X >> FOO_STATS; sleep 1;`` case, using a ``-r
40,60`` range will plot only samples collected between 40th and
Note that as we get closer to the top of the address space, the notation changes
from TB to GB and then MB/KB.
- - "16M TB" might look weird at first sight, but it's an easier to visualize size
+ - "16M TB" might look weird at first sight, but it's an easier way to visualize size
notation than "16 EB", which few will recognize at first sight as 16 exabytes.
It also shows it nicely how incredibly large 64-bit address space is.
projects / linux-2.6-microblaze.git / commitdiff