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2021-06-18riscv: Ensure BPF_JIT_REGION_START aligned with PMD sizeJisheng Zhang
Andreas reported commit fc8504765ec5 ("riscv: bpf: Avoid breaking W^X") breaks booting with one kind of defconfig, I reproduced a kernel panic with the defconfig: [ 0.138553] Unable to handle kernel paging request at virtual address ffffffff81201220 [ 0.139159] Oops [#1] [ 0.139303] Modules linked in: [ 0.139601] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.13.0-rc5-default+ #1 [ 0.139934] Hardware name: riscv-virtio,qemu (DT) [ 0.140193] epc : __memset+0xc4/0xfc [ 0.140416] ra : skb_flow_dissector_init+0x1e/0x82 [ 0.140609] epc : ffffffff8029806c ra : ffffffff8033be78 sp : ffffffe001647da0 [ 0.140878] gp : ffffffff81134b08 tp : ffffffe001654380 t0 : ffffffff81201158 [ 0.141156] t1 : 0000000000000002 t2 : 0000000000000154 s0 : ffffffe001647dd0 [ 0.141424] s1 : ffffffff80a43250 a0 : ffffffff81201220 a1 : 0000000000000000 [ 0.141654] a2 : 000000000000003c a3 : ffffffff81201258 a4 : 0000000000000064 [ 0.141893] a5 : ffffffff8029806c a6 : 0000000000000040 a7 : ffffffffffffffff [ 0.142126] s2 : ffffffff81201220 s3 : 0000000000000009 s4 : ffffffff81135088 [ 0.142353] s5 : ffffffff81135038 s6 : ffffffff8080ce80 s7 : ffffffff80800438 [ 0.142584] s8 : ffffffff80bc6578 s9 : 0000000000000008 s10: ffffffff806000ac [ 0.142810] s11: 0000000000000000 t3 : fffffffffffffffc t4 : 0000000000000000 [ 0.143042] t5 : 0000000000000155 t6 : 00000000000003ff [ 0.143220] status: 0000000000000120 badaddr: ffffffff81201220 cause: 000000000000000f [ 0.143560] [<ffffffff8029806c>] __memset+0xc4/0xfc [ 0.143859] [<ffffffff8061e984>] init_default_flow_dissectors+0x22/0x60 [ 0.144092] [<ffffffff800010fc>] do_one_initcall+0x3e/0x168 [ 0.144278] [<ffffffff80600df0>] kernel_init_freeable+0x1c8/0x224 [ 0.144479] [<ffffffff804868a8>] kernel_init+0x12/0x110 [ 0.144658] [<ffffffff800022de>] ret_from_exception+0x0/0xc [ 0.145124] ---[ end trace f1e9643daa46d591 ]--- After some investigation, I think I found the root cause: commit 2bfc6cd81bd ("move kernel mapping outside of linear mapping") moves BPF JIT region after the kernel: | #define BPF_JIT_REGION_START PFN_ALIGN((unsigned long)&_end) The &_end is unlikely aligned with PMD size, so the front bpf jit region sits with part of kernel .data section in one PMD size mapping. But kernel is mapped in PMD SIZE, when bpf_jit_binary_lock_ro() is called to make the first bpf jit prog ROX, we will make part of kernel .data section RO too, so when we write to, for example memset the .data section, MMU will trigger a store page fault. To fix the issue, we need to ensure the BPF JIT region is PMD size aligned. This patch acchieve this goal by restoring the BPF JIT region to original position, I.E the 128MB before kernel .text section. The modification to kasan_init.c is inspired by Alexandre. Fixes: fc8504765ec5 ("riscv: bpf: Avoid breaking W^X") Reported-by: Andreas Schwab <> Signed-off-by: Jisheng Zhang <> Signed-off-by: Palmer Dabbelt <>
2021-04-26Documentation: riscv: Add documentation that describes the VM layoutAlexandre Ghiti
This new document presents the RISC-V virtual memory layout and is based one the x86 one: it describes the different limits of the different regions of the virtual address space. Signed-off-by: Alexandre Ghiti <> Signed-off-by: Palmer Dabbelt <>
2020-12-03docs: archis: add a per-architecture features listMauro Carvalho Chehab
Add a feature list matrix for each architecture to their respective Kernel books. Signed-off-by: Mauro Carvalho Chehab <> Link: Signed-off-by: Jonathan Corbet <>
2020-01-29Merge tag 'docs-5.6' of git:// Torvalds
Pull documentation updates from Jonathan Corbet: "It has been a relatively quiet cycle for documentation, but there's still a couple of things of note: - Conversion of the NFS documentation to RST - A new document on how to help with documentation (and a maintainer profile entry too) Plus the usual collection of typo fixes, etc" * tag 'docs-5.6' of git:// (40 commits) docs: filesystems: add overlayfs to index.rst docs: usb: remove some broken references scripts/find-unused-docs: Fix massive false positives docs: nvdimm: use ReST notation for subsection zram: correct documentation about sysfs node of huge page writeback Documentation: zram: various fixes in zram.rst Add a maintainer entry profile for documentation Add a document on how to contribute to the documentation docs: Keep up with the location of NoUri Documentation: Call out example SYM_FUNC_* usage as x86-specific Documentation: nfs: fault_injection: convert to ReST Documentation: nfs: pnfs-scsi-server: convert to ReST Documentation: nfs: convert pnfs-block-server to ReST Documentation: nfs: idmapper: convert to ReST Documentation: convert nfsd-admin-interfaces to ReST Documentation: nfs-rdma: convert to ReST Documentation: nfsroot.rst: COSMETIC: refill a paragraph Documentation: nfsroot.txt: convert to ReST Documentation: convert nfs.txt to ReST Documentation: filesystems: convert vfat.txt to RST ...
2020-01-04Documentation: riscv: add patch acceptance guidelinesPaul Walmsley
Formalize, in kernel documentation, the patch acceptance policy for arch/riscv. In summary, it states that as maintainers, we plan to only accept patches for new modules or extensions that have been frozen or ratified by the RISC-V Foundation. We've been following these guidelines for the past few months. In the meantime, we've received quite a bit of feedback that it would be helpful to have these guidelines formally documented. Based on a suggestion from Matthew Wilcox, we also add a link to this file to Documentation/process/index.rst, to make this document easier to find. The format of this document has also been changed to align to the format outlined in the maintainer entry profiles, in accordance with comments from Jon Corbet and Dan Williams. Signed-off-by: Paul Walmsley <> Reviewed-by: Palmer Dabbelt <> Cc: Palmer Dabbelt <> Cc: Albert Ou <> Cc: Krste Asanovic <> Cc: Andrew Waterman <> Cc: Matthew Wilcox <> Cc: Dan Williams <> Cc: Jonathan Corbet <>
2019-12-19RISC-V: Typo fixes in image header and documentation.Atish Patra
There are some typos in boot image header and riscv boot documentation. Fix the typos. Signed-off-by: Atish Patra <> Reviewed-by: Palmer Dabbelt <> Link: Signed-off-by: Jonathan Corbet <>
2019-10-03riscv-docs: correct the sequence of the magic number 2 since it's little endianChester Lin
Correct the sequence of the magic number 2 since it's little endian. Signed-off-by: Chester Lin <> Reviewed-by: Paul Walmsley <> Signed-off-by: Jonathan Corbet <>
2019-09-17Merge tag 'docs-5.4' of git:// Torvalds
Pull documentation updates from Jonathan Corbet: "It's a somewhat calmer cycle for docs this time, as the churn of the mass RST conversion is happily mostly behind us. - A new document on reproducible builds. - We finally got around to zapping the documentation for hardware support that was removed in 2004; one doesn't want to rush these things. - The usual assortment of fixes, typo corrections, etc" * tag 'docs-5.4' of git:// (67 commits) Documentation: kbuild: Add document about reproducible builds docs: printk-formats: Stop encouraging use of unnecessary %h[xudi] and %hh[xudi] Documentation: Add "earlycon=sbi" to the admin guide doc:lock: remove reference to clever use of read-write lock devices.txt: improve entry for comedi (char major 98) docs: mtd: Update spi nor reference driver doc: arm64: fix grammar dtb placed in no attributes region Documentation: sysrq: don't recommend 'S' 'U' before 'B' mailmap: Update email address for Quentin Perret docs: ftrace: clarify when tracing is disabled by the trace file docs: process: fix broken link Documentation/arm/samsung-s3c24xx: Remove stray U+FEFF character to fix title Documentation/arm/sa1100/assabet: Fix 'make assabet_defconfig' command Documentation/arm/sa1100: Remove some obsolete documentation docs/zh_CN: update Chinese howto.rst for latexdocs making Documentation: virt: Fix broken reference to virt tree's index docs: Fix typo on pull requests guide kernel-doc: Allow anonymous enum Documentation: sphinx: Don't parse socket() as identifier reference Documentation: sphinx: Add missing comma to list of strings ...
2019-09-13riscv: modify the Image header to improve compatibility with the ARM64 headerPaul Walmsley
Part of the intention during the definition of the RISC-V kernel image header was to lay the groundwork for a future merge with the ARM64 image header. One error during my original review was not noticing that the RISC-V header's "magic" field was at a different size and position than the ARM64's "magic" field. If the existing ARM64 Image header parsing code were to attempt to parse an existing RISC-V kernel image header format, it would see a magic number 0. This is undesirable, since it's our intention to align as closely as possible with the ARM64 header format. Another problem was that the original "res3" field was not being initialized correctly to zero. Address these issues by creating a 32-bit "magic2" field in the RISC-V header which matches the ARM64 "magic" field. RISC-V binaries will store "RSC\x05" in this field. The intention is that the use of the existing 64-bit "magic" field in the RISC-V header will be deprecated over time. Increment the minor version number of the file format to indicate this change, and update the documentation accordingly. Fix the assembler directives in head.S to ensure that reserved fields are properly zero-initialized. Signed-off-by: Paul Walmsley <> Reported-by: Palmer Dabbelt <> Reviewed-by: Palmer Dabbelt <> Cc: Atish Patra <> Cc: Karsten Merker <> Link: Link:
2019-07-31docs: riscv: convert boot-image-header.txt to ReSTMauro Carvalho Chehab
Convert this small file to ReST format by: - Using a proper markup for the document title; - marking a code block as such; - use tags for Author and date; - use tables for bit map fields. While here, fix a broken reference for a document with is planned but is not here yet. Signed-off-by: Mauro Carvalho Chehab <> Reviewed-by: Atish Patra <> Signed-off-by: Jonathan Corbet <>
2019-07-18Merge tag 'riscv/for-v5.3-rc1' of ↵Linus Torvalds
git:// Pull RISC-V updates from Paul Walmsley: - Hugepage support - "Image" header support for RISC-V kernel binaries, compatible with the current ARM64 "Image" header - Initial page table setup now split into two stages - CONFIG_SOC support (starting with SiFive SoCs) - Avoid reserving memory between RAM start and the kernel in setup_bootmem() - Enable high-res timers and dynamic tick in the RV64 defconfig - Remove long-deprecated gate area stubs - MAINTAINERS updates to switch to the newly-created shared RISC-V git tree, and to fix a issue for patches involving SiFive E-mail addresses Also, one integration fix to resolve a build problem introduced during in the v5.3-rc1 merge window: - Fix build break after macro-to-function conversion in asm-generic/cacheflush.h * tag 'riscv/for-v5.3-rc1' of git:// riscv: fix build break after macro-to-function conversion in generic cacheflush.h RISC-V: Add an Image header that boot loader can parse. RISC-V: Setup initial page tables in two stages riscv: remove free_initrd_mem riscv: ccache: Remove unused variable riscv: Introduce huge page support for 32/64bit kernel x86, arm64: Move ARCH_WANT_HUGE_PMD_SHARE config in arch/Kconfig RISC-V: Fix memory reservation in setup_bootmem() riscv: defconfig: enable SOC_SIFIVE riscv: select SiFive platform drivers with SOC_SIFIVE arch: riscv: add config option for building SiFive's SoC resource riscv: Remove gate area stubs MAINTAINERS: change the arch/riscv git tree to the new shared tree MAINTAINERS: don't automatically patches involving SiFive to the linux-riscv list RISC-V: defconfig: Enable NO_HZ_IDLE and HIGH_RES_TIMERS
2019-07-15docs: add arch doc directories to the indexMauro Carvalho Chehab
Now that several arch documents were converted to ReST, add their indexes to Documentation/index.rst and remove the :orphan: from them. Signed-off-by: Mauro Carvalho Chehab <>
2019-07-11RISC-V: Add an Image header that boot loader can parse.Atish Patra
Currently, the last stage boot loaders such as U-Boot can accept only uImage which is an unnecessary additional step in automating boot process. Add an image header that boot loader understands and boot Linux from flat Image directly. This header is based on ARM64 boot image header and provides an opportunity to combine both ARM64 & RISC-V image headers in future. Also make sure that PE/COFF header can co-exist in the same image so that EFI stub can be supported for RISC-V in future. EFI specification needs PE/COFF image header in the beginning of the kernel image in order to load it as an EFI application. In order to support EFI stub, code0 should be replaced with "MZ" magic string and res4(at offset 0x3c) should point to the rest of the PE/COFF header (which will be added during EFI support). Tested on both QEMU and HiFive Unleashed using OpenSBI + U-Boot + Linux. Signed-off-by: Atish Patra <> Reviewed-by: Karsten Merker <> Tested-by: Karsten Merker <> (QEMU+OpenSBI+U-Boot) Tested-by: Kevin Hilman <> (OpenSBI + U-Boot + Linux) [ fixed whitespace in boot-image-header.txt; converted structure comment to kernel-doc format and added some detail] Signed-off-by: Paul Walmsley <>
2019-06-14docs: riscv: convert docs to ReST and rename to *.rstMauro Carvalho Chehab
The conversion here is trivial: - Adjust the document title's markup - Do some whitespace alignment; - mark literal blocks; - Use ReST way to markup indented lists. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <> Signed-off-by: Jonathan Corbet <>
2018-06-04perf: riscv: Add Document for Future Porting GuideAlan Kao
Reviewed-by: Alex Solomatnikov <> Cc: Nick Hu <> Cc: Greentime Hu <> Signed-off-by: Alan Kao <> Signed-off-by: Palmer Dabbelt <>