summaryrefslogtreecommitdiff
path: root/arch/riscv/kernel/head.S
AgeCommit message (Collapse)Author
2019-08-30riscv: Using CSR numbers to access CSRsBin Meng
Since commit a3182c91ef4e ("RISC-V: Access CSRs using CSR numbers"), we should prefer accessing CSRs using their CSR numbers, but there are several leftovers like sstatus / sptbr we missed. Signed-off-by: Bin Meng <bmeng.cn@gmail.com> Reviewed-by: Anup Patel <anup@brainfault.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>
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 <atish.patra@wdc.com> Reviewed-by: Karsten Merker <merker@debian.org> Tested-by: Karsten Merker <merker@debian.org> (QEMU+OpenSBI+U-Boot) Tested-by: Kevin Hilman <khilman@baylibre.com> (OpenSBI + U-Boot + Linux) [paul.walmsley@sifive.com: fixed whitespace in boot-image-header.txt; converted structure comment to kernel-doc format and added some detail] Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>
2019-07-09RISC-V: Setup initial page tables in two stagesAnup Patel
Currently, the setup_vm() does initial page table setup in one-shot very early before enabling MMU. Due to this, the setup_vm() has to map all possible kernel virtual addresses since it does not know size and location of RAM. This means we have kernel mappings for non-existent RAM and any buggy driver (or kernel) code doing out-of-bound access to RAM will not fault and cause underterministic behaviour. Further, the setup_vm() creates PMD mappings (i.e. 2M mappings) for RV64 systems. This means for PAGE_OFFSET=0xffffffe000000000 (i.e. MAXPHYSMEM_128GB=y), the setup_vm() will require 129 pages (i.e. 516 KB) of memory for initial page tables which is never freed. The memory required for initial page tables will further increase if we chose a lower value of PAGE_OFFSET (e.g. 0xffffff0000000000) This patch implements two-staged initial page table setup, as follows: 1. Early (i.e. setup_vm()): This stage maps kernel image and DTB in a early page table (i.e. early_pg_dir). The early_pg_dir will be used only by boot HART so it can be freed as-part of init memory free-up. 2. Final (i.e. setup_vm_final()): This stage maps all possible RAM banks in the final page table (i.e. swapper_pg_dir). The boot HART will start using swapper_pg_dir at the end of setup_vm_final(). All non-boot HARTs directly use the swapper_pg_dir created by boot HART. We have following advantages with this new approach: 1. Kernel mappings for non-existent RAM don't exists anymore. 2. Memory consumed by initial page tables is now indpendent of the chosen PAGE_OFFSET. 3. Memory consumed by initial page tables on RV64 system is 2 pages (i.e. 8 KB) which has significantly reduced and these pages will be freed as-part of the init memory free-up. The patch also provides a foundation for implementing strict kernel mappings where we protect kernel text and rodata using PTE permissions. Suggested-by: Mike Rapoport <rppt@linux.ibm.com> Signed-off-by: Anup Patel <anup.patel@wdc.com> [paul.walmsley@sifive.com: updated to apply; fixed a checkpatch 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>
2019-05-16RISC-V: Avoid using invalid intermediate translationsPalmer Dabbelt
This is almost entirely a comment. Signed-off-by: Palmer Dabbelt <palmer@sifive.com> Reviewed-by: Anup Patel <anup@brainfault.org>
2019-05-16RISC-V: Access CSRs using CSR numbersAnup Patel
We should prefer accessing CSRs using their CSR numbers because: 1. It compiles fine with older toolchains. 2. We can use latest CSR names in #define macro names of CSR numbers as-per RISC-V spec. 3. We can access newly added CSRs even if toolchain does not recognize newly addes CSRs by name. Signed-off-by: Anup Patel <anup.patel@wdc.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
2019-04-25riscv: cleanup the parse_dtb calling conventionsChristoph Hellwig
No need to pass the hartid, and the dtb address passed is a physical address, so don't pretend it is a kernel pointer. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
2019-04-25riscv: simplify the stack pointer setup in head.SChristoph Hellwig
We don't need THREAD_SIZE in asm-offsets.c as we can just calculate the value of init_thread_union + THREAD_SIZE using cpp, just like we do a few lines above. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Atish Patra <atish.patra@wdc.com> Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
2019-04-25riscv: clear all pending interrupts when bootingChristoph Hellwig
Just in case an old interrupt is pending make sure we clear everything asserted before this kernel started. Based on similar M-mode code in opensbi. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Nick Kossifidis <mick@ics.forth.gr> Reviewed-by: Atish Patra <atish.patra@wdc.com> Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
2018-11-20RISC-V: Build flat and compressed kernel imagesAnup Patel
This patch extends Linux RISC-V build system to build and install: Image - Flat uncompressed kernel image Image.gz - Flat and GZip compressed kernel image Quiet a few bootloaders (such as Uboot, UEFI, etc) are capable of booting flat and compressed kernel images. In case of Uboot, booting Image or Image.gz is achieved using bootm command. The flat and uncompressed kernel image (i.e. Image) is very useful in pre-silicon developent and testing because we can create back-door HEX files for RAM on FPGAs from Image. Signed-off-by: Anup Patel <anup@brainfault.org> Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
2018-10-22RISC-V: Use Linux logical CPU number instead of hartidAtish Patra
Setup the cpu_logical_map during boot. Moreover, every SBI call and PLIC context are based on the physical hartid. Use the logical CPU to hartid mapping to pass correct hartid to respective functions. Signed-off-by: Atish Patra <atish.patra@wdc.com> Reviewed-by: Anup Patel <anup@brainfault.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
2018-08-13RISC-V: Add the directive for alignment of stvec's valueZong Li
The stvec's value must be 4 byte alignment by specification definition. These directives avoid to stvec be set the non-alignment value. Signed-off-by: Zong Li <zong@andestech.com> Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
2018-02-20Rename sbi_save to parse_dtb to improve code readabilityMichael Clark
The sbi_ prefix would seem to indicate an SBI interface, and save is not very specific. After applying this patch, reading head.S makes more sense. Signed-off-by: Michael Clark <michaeljclark@mac.com> Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
2018-01-30riscv: rename sptbr to satpChristoph Hellwig
satp is the name used by the current privileged spec 1.10, use it instead of the old name. The most recent release binutils release (2.29) doesn't know about the satp name yet, so stick to the name from the previous privileged ISA release and comment on the fact. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
2017-11-30RISC-V: move empty_zero_page definition to C and export itOlof Johansson
Needed by some modules (exported by other architectures). Signed-off-by: Olof Johansson <olof@lixom.net> Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
2017-09-26RISC-V: Init and Halt CodePalmer Dabbelt
This contains the various __init C functions, the initial assembly kernel entry point, and the code to reset the system. When a file was init-related this patch contains the entire file. Signed-off-by: Palmer Dabbelt <palmer@dabbelt.com>