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2025-01-08riscv: kprobes: Fix incorrect address calculationNam Cao
p->ainsn.api.insn is a pointer to u32, therefore arithmetic operations are multiplied by four. This is clearly undesirable for this case. Cast it to (void *) first before any calculation. Below is a sample before/after. The dumped memory is two kprobe slots, the first slot has - c.addiw a0, 0x1c (0x7125) - ebreak (0x00100073) and the second slot has: - c.addiw a0, -4 (0x7135) - ebreak (0x00100073) Before this patch: (gdb) x/16xh 0xff20000000135000 0xff20000000135000: 0x7125 0x0000 0x0000 0x0000 0x7135 0x0010 0x0000 0x0000 0xff20000000135010: 0x0073 0x0010 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 After this patch: (gdb) x/16xh 0xff20000000125000 0xff20000000125000: 0x7125 0x0073 0x0010 0x0000 0x7135 0x0073 0x0010 0x0000 0xff20000000125010: 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 Fixes: b1756750a397 ("riscv: kprobes: Use patch_text_nosync() for insn slots") Signed-off-by: Nam Cao <namcao@linutronix.de> Cc: stable@vger.kernel.org Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com> Link: https://lore.kernel.org/r/20241119111056.2554419-1-namcao@linutronix.de Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2024-11-07asm-generic: introduce text-patching.hMike Rapoport (Microsoft)
Several architectures support text patching, but they name the header files that declare patching functions differently. Make all such headers consistently named text-patching.h and add an empty header in asm-generic for architectures that do not support text patching. Link: https://lkml.kernel.org/r/20241023162711.2579610-4-rppt@kernel.org Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> # m68k Acked-by: Arnd Bergmann <arnd@arndb.de> Reviewed-by: Luis Chamberlain <mcgrof@kernel.org> Tested-by: kdevops <kdevops@lists.linux.dev> Cc: Andreas Larsson <andreas@gaisler.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Ard Biesheuvel <ardb@kernel.org> Cc: Borislav Petkov (AMD) <bp@alien8.de> Cc: Brian Cain <bcain@quicinc.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Dinh Nguyen <dinguyen@kernel.org> Cc: Guo Ren <guoren@kernel.org> Cc: Helge Deller <deller@gmx.de> Cc: Huacai Chen <chenhuacai@kernel.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Johannes Berg <johannes@sipsolutions.net> Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de> Cc: Kent Overstreet <kent.overstreet@linux.dev> Cc: Liam R. Howlett <Liam.Howlett@Oracle.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Masami Hiramatsu (Google) <mhiramat@kernel.org> Cc: Matt Turner <mattst88@gmail.com> Cc: Max Filippov <jcmvbkbc@gmail.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Michal Simek <monstr@monstr.eu> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Richard Weinberger <richard@nod.at> Cc: Russell King <linux@armlinux.org.uk> Cc: Song Liu <song@kernel.org> Cc: Stafford Horne <shorne@gmail.com> Cc: Steven Rostedt (Google) <rostedt@goodmis.org> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Uladzislau Rezki (Sony) <urezki@gmail.com> Cc: Vineet Gupta <vgupta@kernel.org> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-06-26riscv: Pass patch_text() the length in bytesSamuel Holland
patch_text_nosync() already handles an arbitrary length of code, so this removes a superfluous loop and reduces the number of icache flushes. Reviewed-by: Björn Töpel <bjorn@rivosinc.com> Signed-off-by: Samuel Holland <samuel.holland@sifive.com> Reviewed-by: Conor Dooley <conor.dooley@microchip.com> Link: https://lore.kernel.org/r/20240327160520.791322-6-samuel.holland@sifive.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2024-06-26riscv: kprobes: Use patch_text_nosync() for insn slotsSamuel Holland
These instructions are not yet visible to the rest of the system, so there is no need to do the whole stop_machine() dance. Reviewed-by: Björn Töpel <bjorn@rivosinc.com> Signed-off-by: Samuel Holland <samuel.holland@sifive.com> Link: https://lore.kernel.org/r/20240327160520.791322-4-samuel.holland@sifive.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2024-05-19Merge tag 'mm-stable-2024-05-17-19-19' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Pull mm updates from Andrew Morton: "The usual shower of singleton fixes and minor series all over MM, documented (hopefully adequately) in the respective changelogs. Notable series include: - Lucas Stach has provided some page-mapping cleanup/consolidation/ maintainability work in the series "mm/treewide: Remove pXd_huge() API". - In the series "Allow migrate on protnone reference with MPOL_PREFERRED_MANY policy", Donet Tom has optimized mempolicy's MPOL_PREFERRED_MANY mode, yielding almost doubled performance in one test. - In their series "Memory allocation profiling" Kent Overstreet and Suren Baghdasaryan have contributed a means of determining (via /proc/allocinfo) whereabouts in the kernel memory is being allocated: number of calls and amount of memory. - Matthew Wilcox has provided the series "Various significant MM patches" which does a number of rather unrelated things, but in largely similar code sites. - In his series "mm: page_alloc: freelist migratetype hygiene" Johannes Weiner has fixed the page allocator's handling of migratetype requests, with resulting improvements in compaction efficiency. - In the series "make the hugetlb migration strategy consistent" Baolin Wang has fixed a hugetlb migration issue, which should improve hugetlb allocation reliability. - Liu Shixin has hit an I/O meltdown caused by readahead in a memory-tight memcg. Addressed in the series "Fix I/O high when memory almost met memcg limit". - In the series "mm/filemap: optimize folio adding and splitting" Kairui Song has optimized pagecache insertion, yielding ~10% performance improvement in one test. - Baoquan He has cleaned up and consolidated the early zone initialization code in the series "mm/mm_init.c: refactor free_area_init_core()". - Baoquan has also redone some MM initializatio code in the series "mm/init: minor clean up and improvement". - MM helper cleanups from Christoph Hellwig in his series "remove follow_pfn". - More cleanups from Matthew Wilcox in the series "Various page->flags cleanups". - Vlastimil Babka has contributed maintainability improvements in the series "memcg_kmem hooks refactoring". - More folio conversions and cleanups in Matthew Wilcox's series: "Convert huge_zero_page to huge_zero_folio" "khugepaged folio conversions" "Remove page_idle and page_young wrappers" "Use folio APIs in procfs" "Clean up __folio_put()" "Some cleanups for memory-failure" "Remove page_mapping()" "More folio compat code removal" - David Hildenbrand chipped in with "fs/proc/task_mmu: convert hugetlb functions to work on folis". - Code consolidation and cleanup work related to GUP's handling of hugetlbs in Peter Xu's series "mm/gup: Unify hugetlb, part 2". - Rick Edgecombe has developed some fixes to stack guard gaps in the series "Cover a guard gap corner case". - Jinjiang Tu has fixed KSM's behaviour after a fork+exec in the series "mm/ksm: fix ksm exec support for prctl". - Baolin Wang has implemented NUMA balancing for multi-size THPs. This is a simple first-cut implementation for now. The series is "support multi-size THP numa balancing". - Cleanups to vma handling helper functions from Matthew Wilcox in the series "Unify vma_address and vma_pgoff_address". - Some selftests maintenance work from Dev Jain in the series "selftests/mm: mremap_test: Optimizations and style fixes". - Improvements to the swapping of multi-size THPs from Ryan Roberts in the series "Swap-out mTHP without splitting". - Kefeng Wang has significantly optimized the handling of arm64's permission page faults in the series "arch/mm/fault: accelerate pagefault when badaccess" "mm: remove arch's private VM_FAULT_BADMAP/BADACCESS" - GUP cleanups from David Hildenbrand in "mm/gup: consistently call it GUP-fast". - hugetlb fault code cleanups from Vishal Moola in "Hugetlb fault path to use struct vm_fault". - selftests build fixes from John Hubbard in the series "Fix selftests/mm build without requiring "make headers"". - Memory tiering fixes/improvements from Ho-Ren (Jack) Chuang in the series "Improved Memory Tier Creation for CPUless NUMA Nodes". Fixes the initialization code so that migration between different memory types works as intended. - David Hildenbrand has improved follow_pte() and fixed an errant driver in the series "mm: follow_pte() improvements and acrn follow_pte() fixes". - David also did some cleanup work on large folio mapcounts in his series "mm: mapcount for large folios + page_mapcount() cleanups". - Folio conversions in KSM in Alex Shi's series "transfer page to folio in KSM". - Barry Song has added some sysfs stats for monitoring multi-size THP's in the series "mm: add per-order mTHP alloc and swpout counters". - Some zswap cleanups from Yosry Ahmed in the series "zswap same-filled and limit checking cleanups". - Matthew Wilcox has been looking at buffer_head code and found the documentation to be lacking. The series is "Improve buffer head documentation". - Multi-size THPs get more work, this time from Lance Yang. His series "mm/madvise: enhance lazyfreeing with mTHP in madvise_free" optimizes the freeing of these things. - Kemeng Shi has added more userspace-visible writeback instrumentation in the series "Improve visibility of writeback". - Kemeng Shi then sent some maintenance work on top in the series "Fix and cleanups to page-writeback". - Matthew Wilcox reduces mmap_lock traffic in the anon vma code in the series "Improve anon_vma scalability for anon VMAs". Intel's test bot reported an improbable 3x improvement in one test. - SeongJae Park adds some DAMON feature work in the series "mm/damon: add a DAMOS filter type for page granularity access recheck" "selftests/damon: add DAMOS quota goal test" - Also some maintenance work in the series "mm/damon/paddr: simplify page level access re-check for pageout" "mm/damon: misc fixes and improvements" - David Hildenbrand has disabled some known-to-fail selftests ni the series "selftests: mm: cow: flag vmsplice() hugetlb tests as XFAIL". - memcg metadata storage optimizations from Shakeel Butt in "memcg: reduce memory consumption by memcg stats". - DAX fixes and maintenance work from Vishal Verma in the series "dax/bus.c: Fixups for dax-bus locking"" * tag 'mm-stable-2024-05-17-19-19' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (426 commits) memcg, oom: cleanup unused memcg_oom_gfp_mask and memcg_oom_order selftests/mm: hugetlb_madv_vs_map: avoid test skipping by querying hugepage size at runtime mm/hugetlb: add missing VM_FAULT_SET_HINDEX in hugetlb_wp mm/hugetlb: add missing VM_FAULT_SET_HINDEX in hugetlb_fault selftests: cgroup: add tests to verify the zswap writeback path mm: memcg: make alloc_mem_cgroup_per_node_info() return bool mm/damon/core: fix return value from damos_wmark_metric_value mm: do not update memcg stats for NR_{FILE/SHMEM}_PMDMAPPED selftests: cgroup: remove redundant enabling of memory controller Docs/mm/damon/maintainer-profile: allow posting patches based on damon/next tree Docs/mm/damon/maintainer-profile: change the maintainer's timezone from PST to PT Docs/mm/damon/design: use a list for supported filters Docs/admin-guide/mm/damon/usage: fix wrong schemes effective quota update command Docs/admin-guide/mm/damon/usage: fix wrong example of DAMOS filter matching sysfs file selftests/damon: classify tests for functionalities and regressions selftests/damon/_damon_sysfs: use 'is' instead of '==' for 'None' selftests/damon/_damon_sysfs: find sysfs mount point from /proc/mounts selftests/damon/_damon_sysfs: check errors from nr_schemes file reads mm/damon/core: initialize ->esz_bp from damos_quota_init_priv() selftests/damon: add a test for DAMOS quota goal ...
2024-05-14riscv: extend execmem_params for generated code allocationsMike Rapoport (IBM)
The memory allocations for kprobes and BPF on RISC-V are not placed in the modules area and these custom allocations are implemented with overrides of alloc_insn_page() and bpf_jit_alloc_exec(). Define MODULES_VADDR and MODULES_END as VMALLOC_START and VMALLOC_END for 32 bit and slightly reorder execmem_params initialization to support both 32 and 64 bit variants, define EXECMEM_KPROBES and EXECMEM_BPF ranges in riscv::execmem_params and drop overrides of alloc_insn_page() and bpf_jit_alloc_exec(). Signed-off-by: Mike Rapoport (IBM) <rppt@kernel.org> Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com> Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
2024-04-25fix missing vmalloc.h includesKent Overstreet
Patch series "Memory allocation profiling", v6. Overview: Low overhead [1] per-callsite memory allocation profiling. Not just for debug kernels, overhead low enough to be deployed in production. Example output: root@moria-kvm:~# sort -rn /proc/allocinfo 127664128 31168 mm/page_ext.c:270 func:alloc_page_ext 56373248 4737 mm/slub.c:2259 func:alloc_slab_page 14880768 3633 mm/readahead.c:247 func:page_cache_ra_unbounded 14417920 3520 mm/mm_init.c:2530 func:alloc_large_system_hash 13377536 234 block/blk-mq.c:3421 func:blk_mq_alloc_rqs 11718656 2861 mm/filemap.c:1919 func:__filemap_get_folio 9192960 2800 kernel/fork.c:307 func:alloc_thread_stack_node 4206592 4 net/netfilter/nf_conntrack_core.c:2567 func:nf_ct_alloc_hashtable 4136960 1010 drivers/staging/ctagmod/ctagmod.c:20 [ctagmod] func:ctagmod_start 3940352 962 mm/memory.c:4214 func:alloc_anon_folio 2894464 22613 fs/kernfs/dir.c:615 func:__kernfs_new_node ... Usage: kconfig options: - CONFIG_MEM_ALLOC_PROFILING - CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT - CONFIG_MEM_ALLOC_PROFILING_DEBUG adds warnings for allocations that weren't accounted because of a missing annotation sysctl: /proc/sys/vm/mem_profiling Runtime info: /proc/allocinfo Notes: [1]: Overhead To measure the overhead we are comparing the following configurations: (1) Baseline with CONFIG_MEMCG_KMEM=n (2) Disabled by default (CONFIG_MEM_ALLOC_PROFILING=y && CONFIG_MEM_ALLOC_PROFILING_BY_DEFAULT=n) (3) Enabled by default (CONFIG_MEM_ALLOC_PROFILING=y && CONFIG_MEM_ALLOC_PROFILING_BY_DEFAULT=y) (4) Enabled at runtime (CONFIG_MEM_ALLOC_PROFILING=y && CONFIG_MEM_ALLOC_PROFILING_BY_DEFAULT=n && /proc/sys/vm/mem_profiling=1) (5) Baseline with CONFIG_MEMCG_KMEM=y && allocating with __GFP_ACCOUNT (6) Disabled by default (CONFIG_MEM_ALLOC_PROFILING=y && CONFIG_MEM_ALLOC_PROFILING_BY_DEFAULT=n) && CONFIG_MEMCG_KMEM=y (7) Enabled by default (CONFIG_MEM_ALLOC_PROFILING=y && CONFIG_MEM_ALLOC_PROFILING_BY_DEFAULT=y) && CONFIG_MEMCG_KMEM=y Performance overhead: To evaluate performance we implemented an in-kernel test executing multiple get_free_page/free_page and kmalloc/kfree calls with allocation sizes growing from 8 to 240 bytes with CPU frequency set to max and CPU affinity set to a specific CPU to minimize the noise. Below are results from running the test on Ubuntu 22.04.2 LTS with 6.8.0-rc1 kernel on 56 core Intel Xeon: kmalloc pgalloc (1 baseline) 6.764s 16.902s (2 default disabled) 6.793s (+0.43%) 17.007s (+0.62%) (3 default enabled) 7.197s (+6.40%) 23.666s (+40.02%) (4 runtime enabled) 7.405s (+9.48%) 23.901s (+41.41%) (5 memcg) 13.388s (+97.94%) 48.460s (+186.71%) (6 def disabled+memcg) 13.332s (+97.10%) 48.105s (+184.61%) (7 def enabled+memcg) 13.446s (+98.78%) 54.963s (+225.18%) Memory overhead: Kernel size: text data bss dec diff (1) 26515311 18890222 17018880 62424413 (2) 26524728 19423818 16740352 62688898 264485 (3) 26524724 19423818 16740352 62688894 264481 (4) 26524728 19423818 16740352 62688898 264485 (5) 26541782 18964374 16957440 62463596 39183 Memory consumption on a 56 core Intel CPU with 125GB of memory: Code tags: 192 kB PageExts: 262144 kB (256MB) SlabExts: 9876 kB (9.6MB) PcpuExts: 512 kB (0.5MB) Total overhead is 0.2% of total memory. Benchmarks: Hackbench tests run 100 times: hackbench -s 512 -l 200 -g 15 -f 25 -P baseline disabled profiling enabled profiling avg 0.3543 0.3559 (+0.0016) 0.3566 (+0.0023) stdev 0.0137 0.0188 0.0077 hackbench -l 10000 baseline disabled profiling enabled profiling avg 6.4218 6.4306 (+0.0088) 6.5077 (+0.0859) stdev 0.0933 0.0286 0.0489 stress-ng tests: stress-ng --class memory --seq 4 -t 60 stress-ng --class cpu --seq 4 -t 60 Results posted at: https://evilpiepirate.org/~kent/memalloc_prof_v4_stress-ng/ [2] https://lore.kernel.org/all/20240306182440.2003814-1-surenb@google.com/ This patch (of 37): The next patch drops vmalloc.h from a system header in order to fix a circular dependency; this adds it to all the files that were pulling it in implicitly. [kent.overstreet@linux.dev: fix arch/alpha/lib/memcpy.c] Link: https://lkml.kernel.org/r/20240327002152.3339937-1-kent.overstreet@linux.dev [surenb@google.com: fix arch/x86/mm/numa_32.c] Link: https://lkml.kernel.org/r/20240402180933.1663992-1-surenb@google.com [kent.overstreet@linux.dev: a few places were depending on sizes.h] Link: https://lkml.kernel.org/r/20240404034744.1664840-1-kent.overstreet@linux.dev [arnd@arndb.de: fix mm/kasan/hw_tags.c] Link: https://lkml.kernel.org/r/20240404124435.3121534-1-arnd@kernel.org [surenb@google.com: fix arc build] Link: https://lkml.kernel.org/r/20240405225115.431056-1-surenb@google.com Link: https://lkml.kernel.org/r/20240321163705.3067592-1-surenb@google.com Link: https://lkml.kernel.org/r/20240321163705.3067592-2-surenb@google.com Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev> Signed-off-by: Suren Baghdasaryan <surenb@google.com> Signed-off-by: Arnd Bergmann <arnd@arndb.de> Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com> Tested-by: Kees Cook <keescook@chromium.org> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Alex Gaynor <alex.gaynor@gmail.com> Cc: Alice Ryhl <aliceryhl@google.com> Cc: Andreas Hindborg <a.hindborg@samsung.com> Cc: Benno Lossin <benno.lossin@proton.me> Cc: "Björn Roy Baron" <bjorn3_gh@protonmail.com> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Christoph Lameter <cl@linux.com> Cc: Dennis Zhou <dennis@kernel.org> Cc: Gary Guo <gary@garyguo.net> Cc: Miguel Ojeda <ojeda@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Tejun Heo <tj@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Wedson Almeida Filho <wedsonaf@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-02-20Merge tag 'for-netdev' of ↵Jakub Kicinski
https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next Daniel Borkmann says: ==================== pull-request: bpf-next 2023-02-17 We've added 64 non-merge commits during the last 7 day(s) which contain a total of 158 files changed, 4190 insertions(+), 988 deletions(-). The main changes are: 1) Add a rbtree data structure following the "next-gen data structure" precedent set by recently-added linked-list, that is, by using kfunc + kptr instead of adding a new BPF map type, from Dave Marchevsky. 2) Add a new benchmark for hashmap lookups to BPF selftests, from Anton Protopopov. 3) Fix bpf_fib_lookup to only return valid neighbors and add an option to skip the neigh table lookup, from Martin KaFai Lau. 4) Add cgroup.memory=nobpf kernel parameter option to disable BPF memory accouting for container environments, from Yafang Shao. 5) Batch of ice multi-buffer and driver performance fixes, from Alexander Lobakin. 6) Fix a bug in determining whether global subprog's argument is PTR_TO_CTX, which is based on type names which breaks kprobe progs, from Andrii Nakryiko. 7) Prep work for future -mcpu=v4 LLVM option which includes usage of BPF_ST insn. Thus improve BPF_ST-related value tracking in verifier, from Eduard Zingerman. 8) More prep work for later building selftests with Memory Sanitizer in order to detect usages of undefined memory, from Ilya Leoshkevich. 9) Fix xsk sockets to check IFF_UP earlier to avoid a NULL pointer dereference via sendmsg(), from Maciej Fijalkowski. 10) Implement BPF trampoline for RV64 JIT compiler, from Pu Lehui. 11) Fix BPF memory allocator in combination with BPF hashtab where it could corrupt special fields e.g. used in bpf_spin_lock, from Hou Tao. 12) Fix LoongArch BPF JIT to always use 4 instructions for function address so that instruction sequences don't change between passes, from Hengqi Chen. * tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (64 commits) selftests/bpf: Add bpf_fib_lookup test bpf: Add BPF_FIB_LOOKUP_SKIP_NEIGH for bpf_fib_lookup riscv, bpf: Add bpf trampoline support for RV64 riscv, bpf: Add bpf_arch_text_poke support for RV64 riscv, bpf: Factor out emit_call for kernel and bpf context riscv: Extend patch_text for multiple instructions Revert "bpf, test_run: fix &xdp_frame misplacement for LIVE_FRAMES" selftests/bpf: Add global subprog context passing tests selftests/bpf: Convert test_global_funcs test to test_loader framework bpf: Fix global subprog context argument resolution logic LoongArch, bpf: Use 4 instructions for function address in JIT bpf: bpf_fib_lookup should not return neigh in NUD_FAILED state bpf: Disable bh in bpf_test_run for xdp and tc prog xsk: check IFF_UP earlier in Tx path Fix typos in selftest/bpf files selftests/bpf: Use bpf_{btf,link,map,prog}_get_info_by_fd() samples/bpf: Use bpf_{btf,link,map,prog}_get_info_by_fd() bpftool: Use bpf_{btf,link,map,prog}_get_info_by_fd() libbpf: Use bpf_{btf,link,map,prog}_get_info_by_fd() libbpf: Introduce bpf_{btf,link,map,prog}_get_info_by_fd() ... ==================== Link: https://lore.kernel.org/r/20230217221737.31122-1-daniel@iogearbox.net Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2023-02-17riscv: Extend patch_text for multiple instructionsPu Lehui
Extend patch_text for multiple instructions. This is the preparaiton for multiple instructions text patching in riscv BPF trampoline, and may be useful for other scenario. Signed-off-by: Pu Lehui <pulehui@huawei.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Tested-by: Björn Töpel <bjorn@rivosinc.com> Reviewed-by: Conor Dooley <conor.dooley@microchip.com> Acked-by: Björn Töpel <bjorn@rivosinc.com> Link: https://lore.kernel.org/bpf/20230215135205.1411105-2-pulehui@huaweicloud.com
2023-02-09riscv: kprobe: Fixup misaligned load textGuo Ren
The current kprobe would cause a misaligned load for the probe point. This patch fixup it with two half-word loads instead. Fixes: c22b0bcb1dd0 ("riscv: Add kprobes supported") Signed-off-by: Guo Ren <guoren@linux.alibaba.com> Signed-off-by: Guo Ren <guoren@kernel.org> Link: https://lore.kernel.org/linux-riscv/878rhig9zj.fsf@all.your.base.are.belong.to.us/ Reported-by: Bjorn Topel <bjorn.topel@gmail.com> Reviewed-by: Björn Töpel <bjorn@kernel.org> Link: https://lore.kernel.org/r/20230204063531.740220-1-guoren@kernel.org Cc: stable@vger.kernel.org Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2023-02-01riscv: kprobe: Fixup kernel panic when probing an illegal positionGuo Ren
The kernel would panic when probed for an illegal position. eg: (CONFIG_RISCV_ISA_C=n) echo 'p:hello kernel_clone+0x16 a0=%a0' >> kprobe_events echo 1 > events/kprobes/hello/enable cat trace Kernel panic - not syncing: stack-protector: Kernel stack is corrupted in: __do_sys_newfstatat+0xb8/0xb8 CPU: 0 PID: 111 Comm: sh Not tainted 6.2.0-rc1-00027-g2d398fe49a4d #490 Hardware name: riscv-virtio,qemu (DT) Call Trace: [<ffffffff80007268>] dump_backtrace+0x38/0x48 [<ffffffff80c5e83c>] show_stack+0x50/0x68 [<ffffffff80c6da28>] dump_stack_lvl+0x60/0x84 [<ffffffff80c6da6c>] dump_stack+0x20/0x30 [<ffffffff80c5ecf4>] panic+0x160/0x374 [<ffffffff80c6db94>] generic_handle_arch_irq+0x0/0xa8 [<ffffffff802deeb0>] sys_newstat+0x0/0x30 [<ffffffff800158c0>] sys_clone+0x20/0x30 [<ffffffff800039e8>] ret_from_syscall+0x0/0x4 ---[ end Kernel panic - not syncing: stack-protector: Kernel stack is corrupted in: __do_sys_newfstatat+0xb8/0xb8 ]--- That is because the kprobe's ebreak instruction broke the kernel's original code. The user should guarantee the correction of the probe position, but it couldn't make the kernel panic. This patch adds arch_check_kprobe in arch_prepare_kprobe to prevent an illegal position (Such as the middle of an instruction). Fixes: c22b0bcb1dd0 ("riscv: Add kprobes supported") Signed-off-by: Guo Ren <guoren@linux.alibaba.com> Signed-off-by: Guo Ren <guoren@kernel.org> Reviewed-by: Björn Töpel <bjorn@kernel.org> Link: https://lore.kernel.org/r/20230201040604.3390509-1-guoren@kernel.org Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2022-12-02riscv: add riscv rethook implementationBinglei Wang
Implement the kretprobes on riscv arch by using rethook machenism which abstracts general kretprobe info into a struct rethook_node to be embedded in the struct kretprobe_instance. Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> Signed-off-by: Binglei Wang <l3b2w1@gmail.com> Signed-off-by: Conor Dooley <conor.dooley@microchip.com> Link: https://lore.kernel.org/r/20221025151831.1097417-1-conor@kernel.org Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2021-09-30kprobes: treewide: Make it harder to refer kretprobe_trampoline directlyMasami Hiramatsu
Since now there is kretprobe_trampoline_addr() for referring the address of kretprobe trampoline code, we don't need to access kretprobe_trampoline directly. Make it harder to refer by renaming it to __kretprobe_trampoline(). Link: https://lkml.kernel.org/r/163163045446.489837.14510577516938803097.stgit@devnote2 Suggested-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2021-09-30kprobes: treewide: Remove trampoline_address from kretprobe_trampoline_handler()Masami Hiramatsu
The __kretprobe_trampoline_handler() callback, called from low level arch kprobes methods, has the 'trampoline_address' parameter, which is entirely superfluous as it basically just replicates: dereference_kernel_function_descriptor(kretprobe_trampoline) In fact we had bugs in arch code where it wasn't replicated correctly. So remove this superfluous parameter and use kretprobe_trampoline_addr() instead. Link: https://lkml.kernel.org/r/163163044546.489837.13505751885476015002.stgit@devnote2 Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Tested-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2021-09-30kprobes: treewide: Cleanup the error messages for kprobesMasami Hiramatsu
This clean up the error/notification messages in kprobes related code. Basically this defines 'pr_fmt()' macros for each files and update the messages which describes - what happened, - what is the kernel going to do or not do, - is the kernel fine, - what can the user do about it. Also, if the message is not needed (e.g. the function returns unique error code, or other error message is already shown.) remove it, and replace the message with WARN_*() macros if suitable. Link: https://lkml.kernel.org/r/163163036568.489837.14085396178727185469.stgit@devnote2 Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2021-07-09Merge tag 'riscv-for-linus-5.14-mw0' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux Pull RISC-V updates from Palmer Dabbelt: "We have a handful of new features for 5.14: - Support for transparent huge pages. - Support for generic PCI resources mapping. - Support for the mem= kernel parameter. - Support for KFENCE. - A handful of fixes to avoid W+X mappings in the kernel. - Support for VMAP_STACK based overflow detection. - An optimized copy_{to,from}_user" * tag 'riscv-for-linus-5.14-mw0' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux: (37 commits) riscv: xip: Fix duplicate included asm/pgtable.h riscv: Fix PTDUMP output now BPF region moved back to module region riscv: __asm_copy_to-from_user: Optimize unaligned memory access and pipeline stall riscv: add VMAP_STACK overflow detection riscv: ptrace: add argn syntax riscv: mm: fix build errors caused by mk_pmd() riscv: Introduce structure that group all variables regarding kernel mapping riscv: Map the kernel with correct permissions the first time riscv: Introduce set_kernel_memory helper riscv: Enable KFENCE for riscv64 RISC-V: Use asm-generic for {in,out}{bwlq} riscv: add ASID-based tlbflushing methods riscv: pass the mm_struct to __sbi_tlb_flush_range riscv: Add mem kernel parameter support riscv: Simplify xip and !xip kernel address conversion macros riscv: Remove CONFIG_PHYS_RAM_BASE_FIXED riscv: Only initialize swiotlb when necessary riscv: fix typo in init.c riscv: Cleanup unused functions riscv: mm: Use better bitmap_zalloc() ...
2021-06-28Merge tag 'perf-core-2021-06-28' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull perf events updates from Ingo Molnar: - Platform PMU driver updates: - x86 Intel uncore driver updates for Skylake (SNR) and Icelake (ICX) servers - Fix RDPMC support - Fix [extended-]PEBS-via-PT support - Fix Sapphire Rapids event constraints - Fix :ppp support on Sapphire Rapids - Fix fixed counter sanity check on Alder Lake & X86_FEATURE_HYBRID_CPU - Other heterogenous-PMU fixes - Kprobes: - Remove the unused and misguided kprobe::fault_handler callbacks. - Warn about kprobes taking a page fault. - Fix the 'nmissed' stat counter. - Misc cleanups and fixes. * tag 'perf-core-2021-06-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: perf: Fix task context PMU for Hetero perf/x86/intel: Fix instructions:ppp support in Sapphire Rapids perf/x86/intel: Add more events requires FRONTEND MSR on Sapphire Rapids perf/x86/intel: Fix fixed counter check warning for some Alder Lake perf/x86/intel: Fix PEBS-via-PT reload base value for Extended PEBS perf/x86: Reset the dirty counter to prevent the leak for an RDPMC task kprobes: Do not increment probe miss count in the fault handler x86,kprobes: WARN if kprobes tries to handle a fault kprobes: Remove kprobe::fault_handler uprobes: Update uprobe_write_opcode() kernel-doc comment perf/hw_breakpoint: Fix DocBook warnings in perf hw_breakpoint perf/core: Fix DocBook warnings perf/core: Make local function perf_pmu_snapshot_aux() static perf/x86/intel/uncore: Enable I/O stacks to IIO PMON mapping on ICX perf/x86/intel/uncore: Enable I/O stacks to IIO PMON mapping on SNR perf/x86/intel/uncore: Generalize I/O stacks to PMON mapping procedure perf/x86/intel/uncore: Drop unnecessary NULL checks after container_of()
2021-06-03kprobes: Do not increment probe miss count in the fault handlerNaveen N. Rao
Kprobes has a counter 'nmissed', that is used to count the number of times a probe handler was not called. This generally happens when we hit a kprobe while handling another kprobe. However, if one of the probe handlers causes a fault, we are currently incrementing 'nmissed'. The comment in fault handler indicates that this can be used to account faults taken by the probe handlers. But, this has never been the intention as is evident from the comment above 'nmissed' in 'struct kprobe': /*count the number of times this probe was temporarily disarmed */ unsigned long nmissed; Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Masami Hiramatsu <mhiramat@kernel.org> Link: https://lkml.kernel.org/r/20210601120150.672652-1-naveen.n.rao@linux.vnet.ibm.com
2021-06-01kprobes: Remove kprobe::fault_handlerPeter Zijlstra
The reason for kprobe::fault_handler(), as given by their comment: * We come here because instructions in the pre/post * handler caused the page_fault, this could happen * if handler tries to access user space by * copy_from_user(), get_user() etc. Let the * user-specified handler try to fix it first. Is just plain bad. Those other handlers are ran from non-preemptible context and had better use _nofault() functions. Also, there is no upstream usage of this. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Acked-by: Masami Hiramatsu <mhiramat@kernel.org> Link: https://lore.kernel.org/r/20210525073213.561116662@infradead.org
2021-05-29riscv: kprobes: Remove redundant kprobe_step_ctxJisheng Zhang
Inspired by commit ba090f9cafd5 ("arm64: kprobes: Remove redundant kprobe_step_ctx"), the ss_pending and match_addr of kprobe_step_ctx are redundant because those can be replaced by KPROBE_HIT_SS and &cur_kprobe->ainsn.api.insn[0] + GET_INSN_LENGTH(cur->opcode) respectively. Remove the kprobe_step_ctx to simplify the code. Signed-off-by: Jisheng Zhang <jszhang@kernel.org> Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
2021-05-22riscv: kprobes: Fix build error when MMU=nJisheng Zhang
lkp reported a randconfig failure: arch/riscv/kernel/probes/kprobes.c:90:22: error: use of undeclared identifier 'PAGE_KERNEL_READ_EXEC' We implemented the alloc_insn_page() to allocate PAGE_KERNEL_READ_EXEC page for kprobes insn page for STRICT_MODULE_RWX. But if MMU=n, we should fall back to the generic weak alloc_insn_page() by generic kprobe subsystem. Fixes: cdd1b2bd358f ("riscv: kprobes: Implement alloc_insn_page()") Signed-off-by: Jisheng Zhang <jszhang@kernel.org> Reported-by: kernel test robot <lkp@intel.com> Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
2021-05-06Merge tag 'riscv-for-linus-5.13-mw0' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux Pull RISC-V updates from Palmer Dabbelt: - Support for the memtest= kernel command-line argument. - Support for building the kernel with FORTIFY_SOURCE. - Support for generic clockevent broadcasts. - Support for the buildtar build target. - Some build system cleanups to pass more LLVM-friendly arguments. - Support for kprobes. - A rearranged kernel memory map, the first part of supporting sv48 systems. - Improvements to kexec, along with support for kdump and crash kernels. - An alternatives-based errata framework, along with support for handling a pair of errata that manifest on some SiFive designs (including the HiFive Unmatched). - Support for XIP. - A device tree for the Microchip PolarFire ICICLE SoC and associated dev board. ... along with a bunch of cleanups. There are already a handful of fixes on the list so there will likely be a part 2. * tag 'riscv-for-linus-5.13-mw0' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux: (45 commits) RISC-V: Always define XIP_FIXUP riscv: Remove 32b kernel mapping from page table dump riscv: Fix 32b kernel build with CONFIG_DEBUG_VIRTUAL=y RISC-V: Fix error code returned by riscv_hartid_to_cpuid() RISC-V: Enable Microchip PolarFire ICICLE SoC RISC-V: Initial DTS for Microchip ICICLE board dt-bindings: riscv: microchip: Add YAML documentation for the PolarFire SoC RISC-V: Add Microchip PolarFire SoC kconfig option RISC-V: enable XIP RISC-V: Add crash kernel support RISC-V: Add kdump support RISC-V: Improve init_resources() RISC-V: Add kexec support RISC-V: Add EM_RISCV to kexec UAPI header riscv: vdso: fix and clean-up Makefile riscv/mm: Use BUG_ON instead of if condition followed by BUG. riscv/kprobe: fix kernel panic when invoking sys_read traced by kprobe riscv: Set ARCH_HAS_STRICT_MODULE_RWX if MMU riscv: module: Create module allocations without exec permissions riscv: bpf: Avoid breaking W^X ...
2021-04-26riscv/kprobe: fix kernel panic when invoking sys_read traced by kprobeLiao Chang
The execution of sys_read end up hitting a BUG_ON() in __find_get_block after installing kprobe at sys_read, the BUG message like the following: [ 65.708663] ------------[ cut here ]------------ [ 65.709987] kernel BUG at fs/buffer.c:1251! [ 65.711283] Kernel BUG [#1] [ 65.712032] Modules linked in: [ 65.712925] CPU: 0 PID: 51 Comm: sh Not tainted 5.12.0-rc4 #1 [ 65.714407] Hardware name: riscv-virtio,qemu (DT) [ 65.715696] epc : __find_get_block+0x218/0x2c8 [ 65.716835] ra : __getblk_gfp+0x1c/0x4a [ 65.717831] epc : ffffffe00019f11e ra : ffffffe00019f56a sp : ffffffe002437930 [ 65.719553] gp : ffffffe000f06030 tp : ffffffe0015abc00 t0 : ffffffe00191e038 [ 65.721290] t1 : ffffffe00191e038 t2 : 000000000000000a s0 : ffffffe002437960 [ 65.723051] s1 : ffffffe00160ad00 a0 : ffffffe00160ad00 a1 : 000000000000012a [ 65.724772] a2 : 0000000000000400 a3 : 0000000000000008 a4 : 0000000000000040 [ 65.726545] a5 : 0000000000000000 a6 : ffffffe00191e000 a7 : 0000000000000000 [ 65.728308] s2 : 000000000000012a s3 : 0000000000000400 s4 : 0000000000000008 [ 65.730049] s5 : 000000000000006c s6 : ffffffe00240f800 s7 : ffffffe000f080a8 [ 65.731802] s8 : 0000000000000001 s9 : 000000000000012a s10: 0000000000000008 [ 65.733516] s11: 0000000000000008 t3 : 00000000000003ff t4 : 000000000000000f [ 65.734434] t5 : 00000000000003ff t6 : 0000000000040000 [ 65.734613] status: 0000000000000100 badaddr: 0000000000000000 cause: 0000000000000003 [ 65.734901] Call Trace: [ 65.735076] [<ffffffe00019f11e>] __find_get_block+0x218/0x2c8 [ 65.735417] [<ffffffe00020017a>] __ext4_get_inode_loc+0xb2/0x2f6 [ 65.735618] [<ffffffe000201b6c>] ext4_get_inode_loc+0x3a/0x8a [ 65.735802] [<ffffffe000203380>] ext4_reserve_inode_write+0x2e/0x8c [ 65.735999] [<ffffffe00020357a>] __ext4_mark_inode_dirty+0x4c/0x18e [ 65.736208] [<ffffffe000206bb0>] ext4_dirty_inode+0x46/0x66 [ 65.736387] [<ffffffe000192914>] __mark_inode_dirty+0x12c/0x3da [ 65.736576] [<ffffffe000180dd2>] touch_atime+0x146/0x150 [ 65.736748] [<ffffffe00010d762>] filemap_read+0x234/0x246 [ 65.736920] [<ffffffe00010d834>] generic_file_read_iter+0xc0/0x114 [ 65.737114] [<ffffffe0001f5d7a>] ext4_file_read_iter+0x42/0xea [ 65.737310] [<ffffffe000163f2c>] new_sync_read+0xe2/0x15a [ 65.737483] [<ffffffe000165814>] vfs_read+0xca/0xf2 [ 65.737641] [<ffffffe000165bae>] ksys_read+0x5e/0xc8 [ 65.737816] [<ffffffe000165c26>] sys_read+0xe/0x16 [ 65.737973] [<ffffffe000003972>] ret_from_syscall+0x0/0x2 [ 65.738858] ---[ end trace fe93f985456c935d ]--- A simple reproducer looks like: echo 'p:myprobe sys_read fd=%a0 buf=%a1 count=%a2' > /sys/kernel/debug/tracing/kprobe_events echo 1 > /sys/kernel/debug/tracing/events/kprobes/myprobe/enable cat /sys/kernel/debug/tracing/trace Here's what happens to hit that BUG_ON(): 1) After installing kprobe at entry of sys_read, the first instruction is replaced by 'ebreak' instruction on riscv64 platform. 2) Once kernel reach the 'ebreak' instruction at the entry of sys_read, it trap into the riscv breakpoint handler, where it do something to setup for coming single-step of origin instruction, including backup the 'sstatus' in pt_regs, followed by disable interrupt during single stepping via clear 'SIE' bit of 'sstatus' in pt_regs. 3) Then kernel restore to the instruction slot contains two instructions, one is original instruction at entry of sys_read, the other is 'ebreak'. Here it trigger a 'Instruction page fault' exception (value at 'scause' is '0xc'), if PF is not filled into PageTabe for that slot yet. 4) Again kernel trap into page fault exception handler, where it choose different policy according to the state of running kprobe. Because afte 2) the state is KPROBE_HIT_SS, so kernel reset the current kprobe and 'pc' points back to the probe address. 5) Because 'epc' point back to 'ebreak' instrution at sys_read probe, kernel trap into breakpoint handler again, and repeat the operations at 2), however 'sstatus' without 'SIE' is keep at 4), it cause the real 'sstatus' saved at 2) is overwritten by the one withou 'SIE'. 6) When kernel cross the probe the 'sstatus' CSR restore with value without 'SIE', and reach __find_get_block where it requires the interrupt must be enabled. Fix this is very trivial, just restore the value of 'sstatus' in pt_regs with backup one at 2) when the instruction being single stepped cause a page fault. Fixes: c22b0bcb1dd02 ("riscv: Add kprobes supported") Signed-off-by: Liao Chang <liaochang1@huawei.com> Cc: stable@vger.kernel.org Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
2021-04-26riscv: kprobes: Implement alloc_insn_page()Jisheng Zhang
Allocate PAGE_KERNEL_READ_EXEC(read only, executable) page for kprobes insn page. This is to prepare for STRICT_MODULE_RWX. Signed-off-by: Jisheng Zhang <jszhang@kernel.org> Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
2021-03-16riscv: fix bugon.cocci warningskernel test robot
Use BUG_ON instead of a if condition followed by BUG. Generated by: scripts/coccinelle/misc/bugon.cocci Fixes: c22b0bcb1dd0 ("riscv: Add kprobes supported") CC: Guo Ren <guoren@linux.alibaba.com> Reported-by: kernel test robot <lkp@intel.com> Signed-off-by: kernel test robot <lkp@intel.com> Signed-off-by: Julia Lawall <julia.lawall@inria.fr> Reviewed-by: Pekka Enberg <penberg@kernel.org> Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
2021-02-18RISC-V: probes: Treat the instruction stream as host-endianPalmer Dabbelt
Neither of these are actually correct: the instruction stream is defined (for versions of the ISA manual newer than 2.2) as a stream of 16-bit little-endian parcels, which is different than just being little-endian. In theory we should represent this as a type, but we don't have any concrete plans for the big endian stuff so it doesn't seem worth the time -- we've got variants of this all over the place. Instead I'm just dropping the unnecessary type conversion, which is a NOP on LE systems but causes an sparse error as the types are all mixed up. Reported-by: kernel test robot <lkp@intel.com> Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com> Acked-by: Guo Ren <guoren@kernel.org> Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
2021-01-14riscv: Add kprobes supportedGuo Ren
This patch enables "kprobe & kretprobe" to work with ftrace interface. It utilized software breakpoint as single-step mechanism. Some instructions which can't be single-step executed must be simulated in kernel execution slot, such as: branch, jal, auipc, la ... Some instructions should be rejected for probing and we use a blacklist to filter, such as: ecall, ebreak, ... We use ebreak & c.ebreak to replace origin instruction and the kprobe handler prepares an executable memory slot for out-of-line execution with a copy of the original instruction being probed. In execution slot we add ebreak behind original instruction to simulate a single-setp mechanism. The patch is based on packi's work [1] and csky's work [2]. - The kprobes_trampoline.S is all from packi's patch - The single-step mechanism is new designed for riscv without hw single-step trap - The simulation codes are from csky - Frankly, all codes refer to other archs' implementation [1] https://lore.kernel.org/linux-riscv/20181113195804.22825-1-me@packi.ch/ [2] https://lore.kernel.org/linux-csky/20200403044150.20562-9-guoren@kernel.org/ Signed-off-by: Guo Ren <guoren@linux.alibaba.com> Co-developed-by: Patrick Stählin <me@packi.ch> Signed-off-by: Patrick Stählin <me@packi.ch> Acked-by: Masami Hiramatsu <mhiramat@kernel.org> Tested-by: Zong Li <zong.li@sifive.com> Reviewed-by: Pekka Enberg <penberg@kernel.org> Cc: Patrick Stählin <me@packi.ch> Cc: Palmer Dabbelt <palmerdabbelt@google.com> Cc: Björn Töpel <bjorn.topel@gmail.com> Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>