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>
When we get booted we want a clear slate without any leaks from previous
supervisors or the firmware. Flush the instruction cache and then clear
all registers to known good values. This is really important for the
upcoming nommu support that runs on M-mode, but can't really harm when
running in S-mode either. Vaguely based on the concepts from opensbi.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Anup Patel <anup@brainfault.org>
Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>
When in M-Mode, we can use the mhartid CSR to get the ID of the running
HART. Doing so, direct M-Mode boot without firmware is possible.
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Reviewed-by: Atish Patra <atish.patra@wdc.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>
Many of the privileged CSRs exist in a supervisor and machine version
that are used very similarly. Provide versions of the CSR names and
fields that map to either the S-mode or M-mode variant depending on
a new CONFIG_RISCV_M_MODE kconfig symbol.
Contains contributions from Damien Le Moal <Damien.LeMoal@wdc.com>
and Paul Walmsley <paul.walmsley@sifive.com>.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Thomas Gleixner <tglx@linutronix.de> # for drivers/clocksource, drivers/irqchip
[paul.walmsley@sifive.com: updated to apply]
Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>
Harts with id greater than or equal to CONFIG_NR_CPUS need to be
disabled. But the kernel can pick any hart as the main hart. So,
before picking the main hart, the kernel must disable harts with ids
greater than or equal to CONFIG_NR_CPUS.
Signed-off-by: Xiang Wang <merle@hardenedlinux.org>
Reviewed-by: Palmer Dabbelt <palmer@sifive.com>
Reviewed-by: Anup Patel <anup.patel@wdc.com>
[paul.walmsley@sifive.com: updated to apply; cleaned up patch
description]
Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>
Add the following new features:
- Generic CPU topology description support for DT-based platforms,
including ARM64, ARM and RISC-V.
- Sparsemem support
- Perf callchain support
- SiFive PLIC irqchip modifications, in preparation for M-mode Linux
and clean up the code base:
- Clean up chip-specific register (CSR) manipulation code, IPIs, TLB
flushing, and the RISC-V CPU-local timer code
- Kbuild cleanup from one of the Kbuild maintainers
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Merge tag 'riscv/for-v5.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux
Pull RISC-V updates from Paul Walmsley:
"Add the following new features:
- Generic CPU topology description support for DT-based platforms,
including ARM64, ARM and RISC-V.
- Sparsemem support
- Perf callchain support
- SiFive PLIC irqchip modifications, in preparation for M-mode Linux
and clean up the code base:
- Clean up chip-specific register (CSR) manipulation code, IPIs, TLB
flushing, and the RISC-V CPU-local timer code
- Kbuild cleanup from one of the Kbuild maintainers"
[ The CPU topology parts came in through the arm64 tree with a shared
branch - Linus ]
* tag 'riscv/for-v5.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux:
irqchip/sifive-plic: set max threshold for ignored handlers
riscv: move the TLB flush logic out of line
riscv: don't use the rdtime(h) pseudo-instructions
riscv: cleanup riscv_cpuid_to_hartid_mask
riscv: optimize send_ipi_single
riscv: cleanup send_ipi_mask
riscv: refactor the IPI code
riscv: Add support for libdw
riscv: Add support for perf registers sampling
riscv: Add perf callchain support
riscv: add arch/riscv/Kbuild
RISC-V: Implement sparsemem
riscv: Using CSR numbers to access CSRs
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 <paul.walmsley@sifive.com>
Reported-by: Palmer Dabbelt <palmer@sifive.com>
Reviewed-by: Palmer Dabbelt <palmer@sifive.com>
Cc: Atish Patra <atish.patra@wdc.com>
Cc: Karsten Merker <merker@debian.org>
Link: https://lore.kernel.org/linux-riscv/194c2f10c9806720623430dbf0cc59a965e50448.camel@wdc.com/T/#u
Link: https://lore.kernel.org/linux-riscv/mhng-755b14c4-8f35-4079-a7ff-e421fd1b02bc@palmer-si-x1e/T/#t
Since commit a3182c91ef ("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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
Needed by some modules (exported by other architectures).
Signed-off-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
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>
Christoph Hellwig