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Hui Li 75ecfab9bf LoongArch: Trigger user-space watchpoints correctly 
commit c8e57ab099 upstream.

In the current code, gdb can set the watchpoint successfully through
ptrace interface, but watchpoint will not be triggered.

When debugging the following code using gdb.

lihui@bogon:~$ cat test.c
  #include <stdio.h>
  int a = 0;
  int main()
  {
	a = 1;
	printf("a = %d\n", a);
	return 0;
  }
lihui@bogon:~$ gcc -g test.c -o test
lihui@bogon:~$ gdb test
...
(gdb) watch a
...
(gdb) r
...
a = 1
[Inferior 1 (process 4650) exited normally]

No watchpoints were triggered, the root causes are:

1. Kernel uses perf_event and hw_breakpoint framework to control
   watchpoint, but the perf_event corresponding to watchpoint is
   not enabled. So it needs to be enabled according to MWPnCFG3
   or FWPnCFG3 PLV bit field in ptrace_hbp_set_ctrl(), and privilege
   is set according to the monitored addr in hw_breakpoint_control().
   Furthermore, add a judgment in ptrace_hbp_set_addr() to ensure
   kernel-space addr cannot be monitored in user mode.

2. The global enable control for all watchpoints is the WE bit of
   CSR.CRMD, and hardware sets the value to 0 when an exception is
   triggered. When the ERTN instruction is executed to return, the
   hardware restores the value of the PWE field of CSR.PRMD here.
   So, before a thread containing watchpoints be scheduled, the PWE
   field of CSR.PRMD needs to be set to 1. Add this modification in
   hw_breakpoint_control().

All changes according to the LoongArch Reference Manual:
https://loongson.github.io/LoongArch-Documentation/LoongArch-Vol1-EN.html#control-and-status-registers-related-to-watchpoints
https://loongson.github.io/LoongArch-Documentation/LoongArch-Vol1-EN.html#basic-control-and-status-registers

With this patch:

lihui@bogon:~$ gdb test
...
(gdb) watch a
Hardware watchpoint 1: a
(gdb) r
...
Hardware watchpoint 1: a

Old value = 0
New value = 1
main () at test.c:6
6		printf("a = %d\n", a);
(gdb) c
Continuing.
a = 1
[Inferior 1 (process 775) exited normally]

Cc: stable@vger.kernel.org
Signed-off-by: Hui Li <lihui@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2024-06-27 13:49:11 +02:00
arch LoongArch: Trigger user-space watchpoints correctly 2024-06-27 13:49:11 +02:00
block block/ioctl: prefer different overflow check 2024-06-27 13:49:01 +02:00
certs certs: Reference revocation list for all keyrings 2023-08-17 20:12:41 +00:00
crypto crypto: ecrdsa - Fix module auto-load on add_key 2024-06-16 13:47:39 +02:00
Documentation mm: fix race between __split_huge_pmd_locked() and GUP-fast 2024-06-16 13:47:40 +02:00
drivers scsi: ufs: core: Free memory allocated for model before reinit 2024-06-27 13:49:11 +02:00
fs cifs: fix typo in module parameter enable_gcm_256 2024-06-27 13:49:11 +02:00
include locking/atomic: scripts: fix ${atomic}_sub_and_test() kerneldoc 2024-06-27 13:49:11 +02:00
init smp: Provide 'setup_max_cpus' definition on UP too 2024-06-16 13:47:49 +02:00
io_uring io_uring/rsrc: fix incorrect assignment of iter->nr_segs in io_import_fixed 2024-06-27 13:49:10 +02:00
ipc Add x86 shadow stack support 2023-08-31 12:20:12 -07:00
kernel tracing: Build event generation tests only as modules 2024-06-27 13:49:05 +02:00
lib lib/test_hmm.c: handle src_pfns and dst_pfns allocation failure 2024-06-12 11:12:08 +02:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm mm/huge_memory: don't unpoison huge_zero_folio 2024-06-21 14:38:46 +02:00
net net: do not leave a dangling sk pointer, when socket creation fails 2024-06-27 13:49:11 +02:00
rust rust: kernel: require Send for Module implementations 2024-05-17 12:01:56 +02:00
samples work around gcc bugs with 'asm goto' with outputs 2024-02-23 09:24:47 +01:00
scripts locking/atomic: scripts: fix ${atomic}_sub_and_test() kerneldoc 2024-06-27 13:49:11 +02:00
security ima: Fix use-after-free on a dentry's dname.name 2024-06-21 14:38:48 +02:00
sound ALSA: hda/realtek: Enable headset mic on IdeaPad 330-17IKB 81DM 2024-06-27 13:49:06 +02:00
tools selftests: openvswitch: Use bash as interpreter 2024-06-27 13:49:07 +02:00
usr initramfs: Encode dependency on KBUILD_BUILD_TIMESTAMP 2023-06-06 17:54:49 +09:00
virt KVM: Always flush async #PF workqueue when vCPU is being destroyed 2024-04-03 15:28:18 +02:00
.clang-format iommu: Add for_each_group_device() 2023-05-23 08:15:51 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore kbuild: rpm-pkg: rename binkernel.spec to kernel.spec 2023-07-25 00:59:33 +09:00
.mailmap 20 hotfixes. 12 are cc:stable and the remainder address post-6.5 issues 2023-10-24 09:52:16 -10:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS USB: Remove Wireless USB and UWB documentation 2023-08-09 14:17:32 +02:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS pwm: Rename pwm_apply_state() to pwm_apply_might_sleep() 2024-06-12 11:12:24 +02:00
Makefile Linux 6.6.35 2024-06-21 14:38:50 +02:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.