kprobe/ftrace: bail out if ftrace was killed #932
Closed
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
|
Upstream branch: ba5ea59 |
When the cpus in the same cluster are all in the idle state, the kernel might put the cluster into a deeper low power state. Call the cluster_pm_enter() before entering the low power state and call the cluster_pm_exit() after the cluster woken up. Signed-off-by: Nick Hu <nick.hu@sifive.com> Link: https://lore.kernel.org/r/20240226065113.1690534-1-nick.hu@sifive.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Alexandre Ghiti <alexghiti@rivosinc.com> says: patch 1 removes a useless memory barrier and patch 2 actually fixes the issue with IPI in the patching code. * b4-shazam-merge: riscv: Fix text patching when IPI are used riscv: Remove superfluous smp_mb() Link: https://lore.kernel.org/r/20240229121056.203419-1-alexghiti@rivosinc.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
…USH_CTX prctl" Charlie Jenkins <charlie@rivosinc.com> says: Improve the performance of icache flushing by creating a new prctl flag PR_RISCV_SET_ICACHE_FLUSH_CTX. The interface is left generic to allow for future expansions such as with the proposed J extension [1]. Documentation is also provided to explain the use case. Patch sent to add PR_RISCV_SET_ICACHE_FLUSH_CTX to man-pages [2]. [1] https://github.com/riscv/riscv-j-extension [2] https://lore.kernel.org/linux-man/20240124-fencei_prctl-v1-1-0bddafcef331@rivosinc.com * b4-shazam-merge: cpumask: Add assign cpu documentation: Document PR_RISCV_SET_ICACHE_FLUSH_CTX prctl riscv: Include riscv_set_icache_flush_ctx prctl riscv: Remove unnecessary irqflags processor.h include Link: https://lore.kernel.org/r/20240312-fencei-v13-0-4b6bdc2bbf32@rivosinc.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
IS_ENABLED(CONFIG_64BIT) in initialization of pgtable_l{4,5}_enabled is
redundant, remove it.
Signed-off-by: Dawei Li <dawei.li@shingroup.cn>
Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Link: https://lore.kernel.org/r/20240320064712.442579-2-dawei.li@shingroup.cn
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
pgtable_l{4,5}_enabled are read only after initialization, make explicit
annotation of __ro_after_init on them.
Signed-off-by: Dawei Li <dawei.li@shingroup.cn>
Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Link: https://lore.kernel.org/r/20240320064712.442579-3-dawei.li@shingroup.cn
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
…ired After commit f51f7a0 ("riscv: enable DMA_BOUNCE_UNALIGNED_KMALLOC for !dma_coherent"), for non-coherent platforms with less than 4GB memory, we rely on users to pass "swiotlb=mmnn,force" kernel parameters to enable DMA bouncing for unaligned kmalloc() buffers. Now let's go further: If no bouncing needed for ZONE_DMA, let kernel automatically allocate 1MB swiotlb buffer per 1GB of RAM for kmalloc() bouncing on non-coherent platforms, so that no need to pass "swiotlb=mmnn,force" any more. The math of "1MB swiotlb buffer per 1GB of RAM for kmalloc() bouncing" is taken from arm64. Users can still force smaller swiotlb buffer by passing "swiotlb=mmnn". Signed-off-by: Jisheng Zhang <jszhang@kernel.org> Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com> Link: https://lore.kernel.org/r/20240325110036.1564-1-jszhang@kernel.org Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Jisheng Zhang <jszhang@kernel.org> says:
This series selects ARCH_USE_CMPXCHG_LOCKREF to enable the
cmpxchg-based lockless lockref implementation for riscv. Then,
implement arch_cmpxchg64_{relaxed|acquire|release}.
After patch1:
Using Linus' test case[1] on TH1520 platform, I see a 11.2% improvement.
On JH7110 platform, I see 12.0% improvement.
After patch2:
on both TH1520 and JH7110 platforms, I didn't see obvious
performance improvement with Linus' test case [1]. IMHO, this may
be related with the fence and lr.d/sc.d hw implementations. In theory,
lr/sc without fence could give performance improvement over lr/sc plus
fence, so add the code here to leave performance improvement room on
newer HW platforms.
* b4-shazam-merge:
riscv: cmpxchg: implement arch_cmpxchg64_{relaxed|acquire|release}
riscv: select ARCH_USE_CMPXCHG_LOCKREF
Link: http://marc.info/?l=linux-fsdevel&m=137782380714721&w=4 [1]
Link: https://lore.kernel.org/r/20240325111038.1700-1-jszhang@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Currently, riscv linux requires at least IMA, so all platforms have a multiplier. And I assume the 'mul' efficiency is comparable or better than a sequence of five or so register-dependent arithmetic instructions. Select ARCH_HAS_FAST_MULTIPLIER to get slightly nicer codegen. Refer to commit f9b4192 ("[PATCH] bitops: hweight() speedup") for more details. In a simple benchmark test calling hweight64() in a loop, it got: about 14% performance improvement on JH7110, tested on Milkv Mars. about 23% performance improvement on TH1520 and SG2042, tested on Sipeed LPI4A and SG2042 platform. a slight performance drop on CV1800B, tested on milkv duo. Among all riscv platforms in my hands, this is the only one which sees a slight performance drop. It means the 'mul' isn't quick enough. However, the situation exists on x86 too, for example, P4 doesn't have fast integer multiplies as said in the above commit, x86 also selects ARCH_HAS_FAST_MULTIPLIER. So let's select ARCH_HAS_FAST_MULTIPLIER which can benefit almost riscv platforms. Samuel also provided some performance numbers: On Unmatched: 20% speedup for __sw_hweight32 and 30% speedup for __sw_hweight64. On D1: 8% speedup for __sw_hweight32 and 8% slowdown for __sw_hweight64. Signed-off-by: Jisheng Zhang <jszhang@kernel.org> Reviewed-by: Samuel Holland <samuel.holland@sifive.com> Tested-by: Samuel Holland <samuel.holland@sifive.com> Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com> Link: https://lore.kernel.org/r/20240325105823.1483-1-jszhang@kernel.org Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
|
Upstream branch: 0a16a17 |
bjoto
force-pushed
the
series/848434=>for-next
branch
from
bc7b14a
to
8bc6d3e
Compare
|
Upstream branch: 0a16a17 |
bjoto
force-pushed
the
series/848434=>for-next
branch
from
8bc6d3e
to
0fedd8f
Compare
If an error happens in ftrace, ftrace_kill() will prevent disarming kprobes. Eventually, the ftrace_ops associated with the kprobes will be freed, yet the kprobes will still be active, and when triggered, they will use the freed memory, likely resulting in a page fault and panic. This behavior can be reproduced quite easily, by creating a kprobe and then triggering a ftrace_kill(). For simplicity, we can simulate an ftrace error with a kernel module like [1]: [1]: https://github.com/brenns10/kernel_stuff/tree/master/ftrace_killer sudo perf probe --add commit_creds sudo perf trace -e probe:commit_creds # In another terminal make sudo insmod ftrace_killer.ko # calls ftrace_kill(), simulating bug # Back to perf terminal # ctrl-c sudo perf probe --del commit_creds After a short period, a page fault and panic would occur as the kprobe continues to execute and uses the freed ftrace_ops. While ftrace_kill() is supposed to be used only in extreme circumstances, it is invoked in FTRACE_WARN_ON() and so there are many places where an unexpected bug could be triggered, yet the system may continue operating, possibly without the administrator noticing. If ftrace_kill() does not panic the system, then we should do everything we can to continue operating, rather than leave a ticking time bomb. Signed-off-by: Stephen Brennan <stephen.s.brennan@oracle.com> Signed-off-by: Björn Töpel <bjorn@rivosinc.com>
|
Upstream branch: 0a16a17 |
bjoto
force-pushed
the
series/848434=>for-next
branch
from
0fedd8f
to
0d073a5
Compare
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Pull request for series with
subject: kprobe/ftrace: bail out if ftrace was killed
version: 1
url: https://patchwork.kernel.org/project/linux-riscv/list/?series=848434