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2024-10-24riscv: Add support for the tagged address ABISamuel Holland
When pointer masking is enabled for userspace, the kernel can accept tagged pointers as arguments to some system calls. Allow this by untagging the pointers in access_ok() and the uaccess routines. The uaccess routines must peform untagging in software because U-mode and S-mode have entirely separate pointer masking configurations. In fact, hardware may not even implement pointer masking for S-mode. Since the number of tag bits is variable, untagged_addr_remote() needs to know what PMLEN to use for the remote mm. Therefore, the pointer masking mode must be the same for all threads sharing an mm. Enforce this with a lock flag in the mm context, as x86 does for LAM. The flag gets reset in init_new_context() during fork(), as the new mm is no longer multithreaded. Reviewed-by: Charlie Jenkins <charlie@rivosinc.com> Tested-by: Charlie Jenkins <charlie@rivosinc.com> Signed-off-by: Samuel Holland <samuel.holland@sifive.com> Link: https://lore.kernel.org/r/20241016202814.4061541-6-samuel.holland@sifive.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2024-06-26riscv: mm: Change attribute from __init to __meminit for page functionsBjörn Töpel
Prepare for memory hotplugging support by changing from __init to __meminit for the page table functions that are used by the upcoming architecture specific callbacks. Changing the __init attribute to __meminit, avoids that the functions are removed after init. The __meminit attribute makes sure the functions are kept in the kernel text post init, but only if memory hotplugging is enabled for the build. Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com> Reviewed-by: David Hildenbrand <david@redhat.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Signed-off-by: Björn Töpel <bjorn@rivosinc.com> Link: https://lore.kernel.org/r/20240605114100.315918-4-bjorn@kernel.org Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2024-04-30Merge patch series "riscv: ASID-related and UP-related TLB flush enhancements"Palmer Dabbelt
Samuel Holland <samuel.holland@sifive.com> says: This series converts uniprocessor kernel builds to use the same TLB flushing code as SMP builds, to take advantage of batching and existing range- and ASID-based TLB flush optimizations. It optimizes out IPIs and SBI calls based on the online CPU count, which also covers the scenario where SMP was enabled at build time but only one CPU is present/online. A final optimization is to use single-ASID flushes wherever possible, to avoid unnecessary TLB misses for kernel mappings. This series has a semantic conflict with the AIA patches that are in linux-next due to the removal of the third parameter of riscv_ipi_set_virq_range(), which is called from imsic_ipi_domain_init() in drivers/irqchip/irq-riscv-imsic-early.c. The resolution is to remove the extra argument from the call site. Here are some numbers from D1 which show the performance impact: v6.9-rc1: System Benchmarks Partial Index BASELINE RESULT INDEX Execl Throughput 43.0 198.5 46.2 File Copy 1024 bufsize 2000 maxblocks 3960.0 73934.4 186.7 File Copy 256 bufsize 500 maxblocks 1655.0 20242.6 122.3 File Copy 4096 bufsize 8000 maxblocks 5800.0 197706.4 340.9 Pipe Throughput 12440.0 176974.2 142.3 Pipe-based Context Switching 4000.0 23626.8 59.1 Process Creation 126.0 449.9 35.7 Shell Scripts (1 concurrent) 42.4 544.4 128.4 Shell Scripts (16 concurrent) --- 35.3 --- Shell Scripts (8 concurrent) 6.0 71.6 119.3 System Call Overhead 15000.0 248072.6 165.4 ======== System Benchmarks Index Score (Partial Only) 110.6 v6.9-rc1 + this patch series: System Benchmarks Partial Index BASELINE RESULT INDEX Execl Throughput 43.0 196.8 45.8 File Copy 1024 bufsize 2000 maxblocks 3960.0 71782.2 181.3 File Copy 256 bufsize 500 maxblocks 1655.0 21269.4 128.5 File Copy 4096 bufsize 8000 maxblocks 5800.0 199424.0 343.8 Pipe Throughput 12440.0 196468.6 157.9 Pipe-based Context Switching 4000.0 24261.8 60.7 Process Creation 126.0 459.0 36.4 Shell Scripts (1 concurrent) 42.4 543.8 128.2 Shell Scripts (16 concurrent) --- 35.5 --- Shell Scripts (8 concurrent) 6.0 71.7 119.6 System Call Overhead 15000.0 259415.2 172.9 ======== System Benchmarks Index Score (Partial Only) 113.0 * b4-shazam-lts: riscv: mm: Always use an ASID to flush mm contexts riscv: mm: Preserve global TLB entries when switching contexts riscv: mm: Make asid_bits a local variable riscv: mm: Use a fixed layout for the MM context ID riscv: mm: Introduce cntx2asid/cntx2version helper macros riscv: Avoid TLB flush loops when affected by SiFive CIP-1200 riscv: Apply SiFive CIP-1200 workaround to single-ASID sfence.vma riscv: mm: Combine the SMP and UP TLB flush code riscv: Only send remote fences when some other CPU is online riscv: mm: Broadcast kernel TLB flushes only when needed riscv: Use IPIs for remote cache/TLB flushes by default riscv: Factor out page table TLB synchronization riscv: Flush the instruction cache during SMP bringup Link: https://lore.kernel.org/r/20240327045035.368512-1-samuel.holland@sifive.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2024-04-29riscv: mm: Use a fixed layout for the MM context IDSamuel Holland
Currently, the size of the ASID field in the MM context ID dynamically depends on the number of hardware-supported ASID bits. This requires reading a global variable to extract either field from the context ID. Instead, allocate the maximum possible number of bits to the ASID field, so the layout of the context ID is known at compile-time. Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com> Signed-off-by: Samuel Holland <samuel.holland@sifive.com> Link: https://lore.kernel.org/r/20240327045035.368512-11-samuel.holland@sifive.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2024-04-29riscv: mm: Introduce cntx2asid/cntx2version helper macrosSamuel Holland
When using the ASID allocator, the MM context ID contains two values: the ASID in the lower bits, and the allocator version number in the remaining bits. Use macros to make this separation more obvious. Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com> Signed-off-by: Samuel Holland <samuel.holland@sifive.com> Link: https://lore.kernel.org/r/20240327045035.368512-10-samuel.holland@sifive.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2024-04-18riscv: Include riscv_set_icache_flush_ctx prctlCharlie Jenkins
Support new prctl with key PR_RISCV_SET_ICACHE_FLUSH_CTX to enable optimization of cross modifying code. This prctl enables userspace code to use icache flushing instructions such as fence.i with the guarantee that the icache will continue to be clean after thread migration. Signed-off-by: Charlie Jenkins <charlie@rivosinc.com> Reviewed-by: Atish Patra <atishp@rivosinc.com> Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com> Reviewed-by: Samuel Holland <samuel.holland@sifive.com> Link: https://lore.kernel.org/r/20240312-fencei-v13-2-4b6bdc2bbf32@rivosinc.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2023-08-23riscv: support the elf-fdpic binfmt loaderGreg Ungerer
Add support for enabling and using the binfmt_elf_fdpic program loader on RISC-V platforms. The most important change is to setup registers during program load to pass the mapping addresses to the new process. One of the interesting features of the elf-fdpic loader is that it also allows appropriately compiled ELF format binaries to be loaded on nommu systems. Appropriate being those compiled with -pie. Signed-off-by: Greg Ungerer <gerg@kernel.org> Acked-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/20230711130754.481209-3-gerg@kernel.org Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2023-03-09Revert "riscv: mm: notify remote harts about mmu cache updates"Sergey Matyukevich
This reverts the remaining bits of commit 4bd1d80efb5a ("riscv: mm: notify remote harts harts about mmu cache updates"). According to bug reports, suggested approach to fix stale TLB entries is not sufficient. It needs to be replaced by a more robust solution. Fixes: 4bd1d80efb5a ("riscv: mm: notify remote harts about mmu cache updates") Reported-by: Zong Li <zong.li@sifive.com> Reported-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com> Signed-off-by: Sergey Matyukevich <sergey.matyukevich@syntacore.com> Cc: stable@vger.kernel.org Reviewed-by: Guo Ren <guoren@kernel.org> Link: https://lore.kernel.org/r/20230226150137.1919750-2-geomatsi@gmail.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2022-12-08riscv: mm: notify remote harts about mmu cache updatesSergey Matyukevich
Current implementation of update_mmu_cache function performs local TLB flush. It does not take into account ASID information. Besides, it does not take into account other harts currently running the same mm context or possible migration of the running context to other harts. Meanwhile TLB flush is not performed for every context switch if ASID support is enabled. Patch [1] proposed to add ASID support to update_mmu_cache to avoid flushing local TLB entirely. This patch takes into account other harts currently running the same mm context as well as possible migration of this context to other harts. For this purpose the approach from flush_icache_mm is reused. Remote harts currently running the same mm context are informed via SBI calls that they need to flush their local TLBs. All the other harts are marked as needing a deferred TLB flush when this mm context runs on them. [1] https://lore.kernel.org/linux-riscv/20220821013926.8968-1-tjytimi@163.com/ Signed-off-by: Sergey Matyukevich <sergey.matyukevich@syntacore.com> Fixes: 65d4b9c53017 ("RISC-V: Implement ASID allocator") Cc: stable@vger.kernel.org Link: https://lore.kernel.org/linux-riscv/20220829205219.283543-1-geomatsi@gmail.com/#t Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2022-10-13riscv: vdso: fix NULL deference in vdso_join_timens() when vforkJisheng Zhang
Testing tools/testing/selftests/timens/vfork_exec.c got below kernel log: [ 6.838454] Unable to handle kernel access to user memory without uaccess routines at virtual address 0000000000000020 [ 6.842255] Oops [#1] [ 6.842871] Modules linked in: [ 6.844249] CPU: 1 PID: 64 Comm: vfork_exec Not tainted 6.0.0-rc3-rt15+ #8 [ 6.845861] Hardware name: riscv-virtio,qemu (DT) [ 6.848009] epc : vdso_join_timens+0xd2/0x110 [ 6.850097] ra : vdso_join_timens+0xd2/0x110 [ 6.851164] epc : ffffffff8000635c ra : ffffffff8000635c sp : ff6000000181fbf0 [ 6.852562] gp : ffffffff80cff648 tp : ff60000000fdb700 t0 : 3030303030303030 [ 6.853852] t1 : 0000000000000030 t2 : 3030303030303030 s0 : ff6000000181fc40 [ 6.854984] s1 : ff60000001e6c000 a0 : 0000000000000010 a1 : ffffffff8005654c [ 6.856221] a2 : 00000000ffffefff a3 : 0000000000000000 a4 : 0000000000000000 [ 6.858114] a5 : 0000000000000000 a6 : 0000000000000008 a7 : 0000000000000038 [ 6.859484] s2 : ff60000001e6c068 s3 : ff6000000108abb0 s4 : 0000000000000000 [ 6.860751] s5 : 0000000000001000 s6 : ffffffff8089dc40 s7 : ffffffff8089dc38 [ 6.862029] s8 : ffffffff8089dc30 s9 : ff60000000fdbe38 s10: 000000000000005e [ 6.863304] s11: ffffffff80cc3510 t3 : ffffffff80d1112f t4 : ffffffff80d1112f [ 6.864565] t5 : ffffffff80d11130 t6 : ff6000000181fa00 [ 6.865561] status: 0000000000000120 badaddr: 0000000000000020 cause: 000000000000000d [ 6.868046] [<ffffffff8008dc94>] timens_commit+0x38/0x11a [ 6.869089] [<ffffffff8008dde8>] timens_on_fork+0x72/0xb4 [ 6.870055] [<ffffffff80190096>] begin_new_exec+0x3c6/0x9f0 [ 6.871231] [<ffffffff801d826c>] load_elf_binary+0x628/0x1214 [ 6.872304] [<ffffffff8018ee7a>] bprm_execve+0x1f2/0x4e4 [ 6.873243] [<ffffffff8018f90c>] do_execveat_common+0x16e/0x1ee [ 6.874258] [<ffffffff8018f9c8>] sys_execve+0x3c/0x48 [ 6.875162] [<ffffffff80003556>] ret_from_syscall+0x0/0x2 [ 6.877484] ---[ end trace 0000000000000000 ]--- This is because the mm->context.vdso_info is NULL in vfork case. From another side, mm->context.vdso_info either points to vdso info for RV64 or vdso info for compat, there's no need to bloat riscv's mm_context_t, we can handle the difference when setup the additional page for vdso. Signed-off-by: Jisheng Zhang <jszhang@kernel.org> Suggested-by: Palmer Dabbelt <palmer@rivosinc.com> Fixes: 3092eb456375 ("riscv: compat: vdso: Add setup additional pages implementation") Link: https://lore.kernel.org/r/20220924070737.3048-1-jszhang@kernel.org Cc: stable@vger.kernel.org Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2022-04-26riscv: compat: vdso: Add setup additional pages implementationGuo Ren
Reconstruct __setup_additional_pages() by appending vdso info pointer argument to meet compat_vdso_info requirement. And change vm_special_mapping *dm, *cm initialization into static. Signed-off-by: Guo Ren <guoren@linux.alibaba.com> Signed-off-by: Guo Ren <guoren@kernel.org> Reviewed-by: Palmer Dabbelt <palmer@rivosinc.com> Tested-by: Heiko Stuebner <heiko@sntech.de> Link: https://lore.kernel.org/r/20220405071314.3225832-18-guoren@kernel.org Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2021-02-18RISC-V: Implement ASID allocatorAnup Patel
Currently, we do local TLB flush on every MM switch. This is very harsh on performance because we are forcing page table walks after every MM switch. This patch implements ASID allocator for assigning an ASID to a MM context. The number of ASIDs are limited in HW so we create a logical entity named CONTEXTID for assigning to MM context. The lower bits of CONTEXTID are ASID and upper bits are VERSION number. The number of usable ASID bits supported by HW are detected at boot-time by writing 1s to ASID bits in SATP CSR. We allocate new CONTEXTID on first MM switch for a MM context where the ASID is allocated from an ASID bitmap and VERSION is provide by an atomic counter. At time of allocating new CONTEXTID, if we run out of available ASIDs then: 1. We flush the ASID bitmap 2. Increment current VERSION atomic counter 3. Re-allocate ASID from ASID bitmap 4. Flush TLB on all CPUs 5. Try CONTEXTID re-assignment on all CPUs Please note that we don't use ASID #0 because it is used at boot-time by all CPUs for initial MM context. Also, newly created context is always assigned CONTEXTID #0 (i.e. VERSION #0 and ASID #0) which is an invalid context in our implementation. Using above approach, we have virtually infinite CONTEXTIDs on-top-of limited number of HW ASIDs. This approach is inspired from ASID allocator used for Linux ARM/ARM64 but we have adapted it for RISC-V. Overall, this ASID allocator helps us reduce rate of local TLB flushes on every CPU thereby increasing performance. This patch is tested on QEMU virt machine, Spike and SiFive Unleashed board. On QEMU virt machine, we see some (3-5% approx) performance improvement with SW emulated TLBs provided by QEMU. Unfortunately, the ASID bits of the SATP CSR are not implemented on Spike and SiFive Unleashed board so we don't see any change in performance. On real HW having all ASID bits implemented, the performance gains will be much more due improved sharing of TLB among different processes. Signed-off-by: Anup Patel <anup.patel@wdc.com> Reviewed-by: Palmer Dabbelt <palmerdabbelt@google.com> Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
2020-10-02RISC-V: Add EFI runtime servicesAtish Patra
This patch adds EFI runtime service support for RISC-V. Signed-off-by: Atish Patra <atish.patra@wdc.com> [ardb: - Remove the page check] Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Acked-by: Ard Biesheuvel <ardb@kernel.org> Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
2019-11-17riscv: add nommu supportChristoph Hellwig
The kernel runs in M-mode without using page tables, and thus can't run bare metal without help from additional firmware. Most of the patch is just stubbing out code not needed without page tables, but there is an interesting detail in the signals implementation: - The normal RISC-V syscall ABI only implements rt_sigreturn as VDSO entry point, but the ELF VDSO is not supported for nommu Linux. We instead copy the code to call the syscall onto the stack. In addition to enabling the nommu code a new defconfig for a small kernel image that can run in nommu mode on qemu is also provided, to run a kernel in qemu you can use the following command line: qemu-system-riscv64 -smp 2 -m 64 -machine virt -nographic \ -kernel arch/riscv/boot/loader \ -drive file=rootfs.ext2,format=raw,id=hd0 \ -device virtio-blk-device,drive=hd0 Contains contributions from Damien Le Moal <Damien.LeMoal@wdc.com>. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Anup Patel <anup@brainfault.org> [paul.walmsley@sifive.com: updated to apply; add CONFIG_MMU guards around PCI_IOBASE definition to fix build issues; fixed checkpatch issues; move the PCI_IO_* and VMEMMAP address space macros along with the others; resolve sparse warning] Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>
2019-06-05treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 286Thomas Gleixner
Based on 1 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of the gnu general public license as published by the free software foundation version 2 this program is distributed in the hope that it will be useful but without any warranty without even the implied warranty of merchantability or fitness for a particular purpose see the gnu general public license for more details extracted by the scancode license scanner the SPDX license identifier GPL-2.0-only has been chosen to replace the boilerplate/reference in 97 file(s). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Allison Randal <allison@lohutok.net> Reviewed-by: Alexios Zavras <alexios.zavras@intel.com> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190529141901.025053186@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-30RISC-V: Flush I$ when making a dirty page executableAndrew Waterman
The RISC-V ISA allows for instruction caches that are not coherent WRT stores, even on a single hart. As a result, we need to explicitly flush the instruction cache whenever marking a dirty page as executable in order to preserve the correct system behavior. Local instruction caches aren't that scary (our implementations actually flush the cache, but RISC-V is defined to allow higher-performance implementations to exist), but RISC-V defines no way to perform an instruction cache shootdown. When explicitly asked to do so we can shoot down remote instruction caches via an IPI, but this is a bit on the slow side. Instead of requiring an IPI to all harts whenever marking a page as executable, we simply flush the currently running harts. In order to maintain correct behavior, we additionally mark every other hart as needing a deferred instruction cache which will be taken before anything runs on it. Signed-off-by: Andrew Waterman <andrew@sifive.com> Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
2017-09-26RISC-V: User-facing APIPalmer Dabbelt
This patch contains code that is in some way visible to the user: including via system calls, the VDSO, module loading and signal handling. It also contains some generic code that is ABI visible. Signed-off-by: Palmer Dabbelt <palmer@dabbelt.com>
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