linux.git/arch/riscv/kernel/patch.c, branch v5.10.258 Clone of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git RISC-V: Don't check text_mutex during stop_machine 2023-03-17T07:45:13+00:00 Conor Dooley conor.dooley@microchip.com 2023-03-03T14:37:55+00:00 ab89b8a67fbbc37c34c2ecb3ed0d7d2ea4bc4c3d [ Upstream commit 2a8db5ec4a28a0fce822d10224db9471a44b6925 ] We're currently using stop_machine() to update ftrace & kprobes, which means that the thread that takes text_mutex during may not be the same as the thread that eventually patches the code. This isn't actually a race because the lock is still held (preventing any other concurrent accesses) and there is only one thread running during stop_machine(), but it does trigger a lockdep failure. This patch just elides the lockdep check during stop_machine. Fixes: c15ac4fd60d5 ("riscv/ftrace: Add dynamic function tracer support") Suggested-by: Steven Rostedt <rostedt@goodmis.org> Reported-by: Changbin Du <changbin.du@gmail.com> Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com> Signed-off-by: Conor Dooley <conor.dooley@microchip.com> Link: https://lore.kernel.org/r/20230303143754.4005217-1-conor.dooley@microchip.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 2a8db5ec4a28a0fce822d10224db9471a44b6925 ]

We're currently using stop_machine() to update ftrace & kprobes, which
means that the thread that takes text_mutex during may not be the same
as the thread that eventually patches the code.  This isn't actually a
race because the lock is still held (preventing any other concurrent
accesses) and there is only one thread running during stop_machine(),
but it does trigger a lockdep failure.

This patch just elides the lockdep check during stop_machine.

Fixes: c15ac4fd60d5 ("riscv/ftrace: Add dynamic function tracer support")
Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Reported-by: Changbin Du <changbin.du@gmail.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230303143754.4005217-1-conor.dooley@microchip.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
riscv: patch_text: Fixup last cpu should be master 2022-05-09T07:04:59+00:00 Guo Ren guoren@linux.alibaba.com 2022-04-06T14:16:49+00:00 8fcce58c59ddb026c3c86d29ceb98287cc91f51f commit 8ec1442953c66a1d8462cccd8c20b7ba561f5915 upstream. These patch_text implementations are using stop_machine_cpuslocked infrastructure with atomic cpu_count. The original idea: When the master CPU patch_text, the others should wait for it. But current implementation is using the first CPU as master, which couldn't guarantee the remaining CPUs are waiting. This patch changes the last CPU as the master to solve the potential risk. Signed-off-by: Guo Ren <guoren@linux.alibaba.com> Signed-off-by: Guo Ren <guoren@kernel.org> Acked-by: Palmer Dabbelt <palmer@rivosinc.com> Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org> Fixes: 043cb41a85de ("riscv: introduce interfaces to patch kernel code") Cc: stable@vger.kernel.org Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 8ec1442953c66a1d8462cccd8c20b7ba561f5915 upstream.

These patch_text implementations are using stop_machine_cpuslocked
infrastructure with atomic cpu_count. The original idea: When the
master CPU patch_text, the others should wait for it. But current
implementation is using the first CPU as master, which couldn't
guarantee the remaining CPUs are waiting. This patch changes the
last CPU as the master to solve the potential risk.

Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Signed-off-by: Guo Ren <guoren@kernel.org>
Acked-by: Palmer Dabbelt <palmer@rivosinc.com>
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Fixes: 043cb41a85de ("riscv: introduce interfaces to patch kernel code")
Cc: stable@vger.kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
maccess: rename probe_kernel_{read,write} to copy_{from,to}_kernel_nofault 2020-06-17T17:57:41+00:00 Christoph Hellwig hch@lst.de 2020-06-17T07:37:53+00:00 fe557319aa06c23cffc9346000f119547e0f289a Better describe what these functions do. Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> 
Better describe what these functions do.

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
riscv: fix build warning of missing prototypes 2020-06-10T02:11:27+00:00 Zong Li zong.li@sifive.com 2020-06-01T07:10:58+00:00 05589dde649cd954a122b0ebb2cbe4ade8a80e98 Add the missing header in file, it was lost in original implementation. The warning message as follows: - no previous prototype for 'patch_text_nosync' [-Wmissing-prototypes] - no previous prototype for 'patch_text' [-Wmissing-prototypes] Changed in v2: - Correct the typo of commit message. Signed-off-by: Zong Li <zong.li@sifive.com> Reported-by: kbuild test robot <lkp@intel.com> Reviewed-by: Atish Patra <atish.patra@wdc.com> Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com> 
Add the missing header in file, it was lost in original implementation.

The warning message as follows:
 - no previous prototype for 'patch_text_nosync' [-Wmissing-prototypes]
 - no previous prototype for 'patch_text' [-Wmissing-prototypes]

Changed in v2:
 - Correct the typo of commit message.

Signed-off-by: Zong Li <zong.li@sifive.com>
Reported-by: kbuild test robot <lkp@intel.com>
Reviewed-by: Atish Patra <atish.patra@wdc.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
riscv: Use text_mutex instead of patch_lock 2020-05-18T18:38:16+00:00 Zong Li zong.li@sifive.com 2020-04-21T07:30:01+00:00 0ff7c3b331276f584bde3ae9a16bacd8fa3d01e6 We don't need the additional lock protection when patching the text. There are two patching interfaces here: - patch_text: patch code and always synchronize with stop_machine() - patch_text_nosync: patch code without synchronization, it's caller's responsibility to synchronize all CPUs if needed. For the first one, stop_machine() is protected by its own mutex, and also the irq is already disabled here. For the second one, in risc-v real case now, it would be used to ftrace patching the mcount function, since it already running under kstop_machine(), no other thread will run, so we could use text_mutex on ftrace side. Signed-off-by: Zong Li <zong.li@sifive.com> Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org> Reviewed-by: Palmer Dabbelt <palmerdabbelt@google.com> Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com> 
We don't need the additional lock protection when patching the text.

There are two patching interfaces here:
 - patch_text: patch code and always synchronize with stop_machine()
 - patch_text_nosync: patch code without synchronization, it's caller's
                      responsibility to synchronize all CPUs if needed.

For the first one, stop_machine() is protected by its own mutex, and
also the irq is already disabled here.

For the second one, in risc-v real case now, it would be used to ftrace
patching the mcount function, since it already running under
kstop_machine(), no other thread will run, so we could use text_mutex
on ftrace side.

Signed-off-by: Zong Li <zong.li@sifive.com>
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Reviewed-by: Palmer Dabbelt <palmerdabbelt@google.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
riscv: Use NOKPROBE_SYMBOL() instead of __krpobes annotation 2020-05-18T18:38:15+00:00 Zong Li zong.li@sifive.com 2020-04-21T07:30:00+00:00 5303df244cbf2d9e5d37816c91c595a7afb7649a The __kprobes annotation is old style, so change it to NOKPROBE_SYMBOL(). Signed-off-by: Zong Li <zong.li@sifive.com> Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org> Reviewed-by: Palmer Dabbelt <palmerdabbelt@google.com> Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com> 
The __kprobes annotation is old style, so change it to NOKPROBE_SYMBOL().

Signed-off-by: Zong Li <zong.li@sifive.com>
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Reviewed-by: Palmer Dabbelt <palmerdabbelt@google.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
riscv: Remove the 'riscv_' prefix of function name 2020-05-18T18:38:13+00:00 Zong Li zong.li@sifive.com 2020-04-21T07:29:59+00:00 b80b3d582ebd8c7c49687319b3c624e03c4b2b93 Refactor the function name by removing the 'riscv_' prefix, it would be better unless it could mix up with arch-independent functions. Signed-off-by: Zong Li <zong.li@sifive.com> Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org> Reviewed-by: Palmer Dabbelt <palmerdabbelt@google.com> Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com> 
Refactor the function name by removing the 'riscv_' prefix, it would be
better unless it could mix up with arch-independent functions.

Signed-off-by: Zong Li <zong.li@sifive.com>
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Reviewed-by: Palmer Dabbelt <palmerdabbelt@google.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
riscv: introduce interfaces to patch kernel code 2020-03-26T16:24:52+00:00 Zong Li zong.li@sifive.com 2020-03-09T16:55:43+00:00 043cb41a85de1c0e944da61ad7a264960e22c865 On strict kernel memory permission, we couldn't patch code without writable permission. Preserve two holes in fixmap area, so we can map the kernel code temporarily to fixmap area, then patch the instructions. We need two pages here because we support the compressed instruction, so the instruction might be align to 2 bytes. When patching the 32-bit length instruction which is 2 bytes alignment, it will across two pages. Introduce two interfaces to patch kernel code: riscv_patch_text_nosync: - patch code without synchronization, it's caller's responsibility to synchronize all CPUs if needed. riscv_patch_text: - patch code and always synchronize with stop_machine() Signed-off-by: Zong Li <zong.li@sifive.com> Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com> 
On strict kernel memory permission, we couldn't patch code without
writable permission. Preserve two holes in fixmap area, so we can map
the kernel code temporarily to fixmap area, then patch the instructions.

We need two pages here because we support the compressed instruction, so
the instruction might be align to 2 bytes. When patching the 32-bit
length instruction which is 2 bytes alignment, it will across two pages.

Introduce two interfaces to patch kernel code:
riscv_patch_text_nosync:
 - patch code without synchronization, it's caller's responsibility to
   synchronize all CPUs if needed.
riscv_patch_text:
 - patch code and always synchronize with stop_machine()

Signed-off-by: Zong Li <zong.li@sifive.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>