coreboot.git - my copy of coreboot

Age	Commit message (Collapse)	Author
2024-03-14	arch/riscv: support physical memory protection (PMP) registers	Ronald G Minnich
	PMP (Physical Memory Protection) is a feature of the RISC-V Privileged Architecture spec, that allows defining region(s) of the address space to be protected in a variety of ways: ranges for M mode can be protected against access from lower privilege levels, and M mode can be locked out of accessig to memory reserved for lower privilege levels. Limits on Read, Write, and Execute are allowed. In coreboot, we protect against Write and Execute of PMP code from lower levels, but allow Reading, so as to ease data structure access. PMP is not a security boundary, it is an accident prevention device. PMP is used here to protect persistent ramstage code that is used to support SBI, e.g. printk and some data structures. It also protects the SBI stacks. Note that there is one stack per hart. There are 512- and 1024-hart SoC's being built today, so the stack should be kept small. PMP is not a general purpose protection mechanism and it is easy to get around it. For example, S mode can stage a DMA that overwrites all the M mode code. PMP is, rather, a way to avoid simple accidents. It is understood that PMP depends on proper OS behavior to implement true SBI security (personal conversation with a RISC-V architect). Think of PMP as "Protection Minus Protection". PMP is also a very limited resource, as defined in the architecture. This language is instructive: "PMP entries are described by an 8-bit configuration register and one XLEN-bit address register. Some PMP settings additionally use the address register associated with the preceding PMP entry. Up to 16 PMP entries are supported. If any PMP entries are implemented, then all PMP CSRs must be implemented, but all PMP CSR fields are WARL and may be hardwired to zero. PMP CSRs are only accessible to M-mode." In other words if you implement PMP even a little, you have to impelement it all; but you can implement it in part by simply returning 0 for a pmpcfg. Also, PMP address registers (pmpaddr) don't have to implement all the bits. On a SiFive FU740, for example, PMP only implements bits 33:0, i.e. a 34 bit address. PMPs are just packed with all kinds of special cases. There are no requirements that you read back what you wrote to the pmpaddr registers. The earlier PMP code would die if the read did not match the write, but, since pmpaddr are WARL, that was not correct. An SoC can just decide it only does 4096-byte granularity, on TOR PMP types, and that is your problem if you wanted finer granulatiry. SoC's don't have to implement all the high order bits either. And, to reiterate, there is no requirement about which of the pmpcfg are implemented. Implementing just pmpcfg15 is allowed. The coreboot SBI code was written before PMP existed. In order for coreboot SBI code to work, this patch is necessary. With this change, a simple S-mode payload that calls SBI putchar works: 1: li a7, 1 li a0, 48 ecall j 1b Without this change, it will not work. Getting this to build on RV32 required changes to the API, as it was incorrect. In RV32, PMP entries are 34 bits. Hence, the setup_pmp needed to accept u64. So, uinptr_t can not be used, as on 32 bits they are only 32 bit numbers. The internal API uses uintptr_t, but the exported API uses u64, so external code does not have to think about right shifts on base and size. Errors are detected: an error in base and size will result in a BIOS_EMERG print, but not a panic. Boots not bricks if possible. There are small changes to the internal API to reduce stack pressure: there's no need to have two pmpcfg_t on the stack when one will do. TEST: Linux now boots partly on the SiFive unmatched. There are changes in flight on the coreboot SBI that will allow Linux to boot further, but they are out of scope for this patch. Currently, clk_ignore_unused is required, this requires a separate patch. Change-Id: I6edce139d340783148cbb446cde004ba96e67944 Signed-off-by: Ronald G Minnich <rminnich@gmail.com> Reviewed-on: https://review.coreboot.org/c/coreboot/+/81153 Tested-by: build bot (Jenkins) <no-reply@coreboot.org> Reviewed-by: Philipp Hug <philipp@hug.cx>
2024-03-09	arch/riscv: Add SMP support for exception handler	Xiang Wang
	Change-Id: Ia1f97b82e329f6358061072f98278cf56b503618 Signed-off-by: Xiang Wang <merle@hardenedlinux.org> Reviewed-on: https://review.coreboot.org/c/coreboot/+/68841 Reviewed-by: Philipp Hug <philipp@hug.cx> Tested-by: build bot (Jenkins) <no-reply@coreboot.org> Reviewed-by: ron minnich <rminnich@gmail.com>
2023-12-09	arch/riscv/payload: Remove old RISC-V CSR names	Lennart Eichhorn
	LLVM/clang 17 removed support for CSR names that are no longer included in the RISC-V ISA Manual Privileged Specification since version 1.12. Related LLVM commit: https://reviews.llvm.org/D149278 Change-Id: I7c8f2a06a109333f95230bf0a3056c8d5c8a9132 Signed-off-by: Lennart Eichhorn <lennarteichhorn@googlemail.com> Reviewed-on: https://review.coreboot.org/c/coreboot/+/79364 Tested-by: build bot (Jenkins) <no-reply@coreboot.org> Reviewed-by: Maximilian Brune <maximilian.brune@9elements.com> Reviewed-by: Felix Singer <service+coreboot-gerrit@felixsinger.de>
2020-05-11	treewide: Remove "this file is part of" lines	Patrick Georgi
	Stefan thinks they don't add value. Command used: sed -i -e '/file is part of /d' $(git grep "file is part of " \|egrep ":( /\.\/\$\|#\|;#\|-- \| \ )" \| cut -d: -f1 \|grep -v crossgcc \|grep -v gcov \| grep -v /elf.h \|grep -v nvramtool) The exceptions are for: - crossgcc (patch file) - gcov (imported from gcc) - elf.h (imported from GNU's libc) - nvramtool (more complicated header) The removed lines are: - fmt.Fprintln(f, "/* This file is part of the coreboot project. /") -# This file is part of a set of unofficial pre-commit hooks available -/ This file is part of coreboot / -# This file is part of msrtool. -/ This file is part of msrtool. / - This file is part of ncurses, designed to be appended after curses.h.in -/* This file is part of pgtblgen. / - This file is part of the coreboot project. - /* This file is part of the coreboot project. / -# This file is part of the coreboot project. -# This file is part of the coreboot project. -## This file is part of the coreboot project. --- This file is part of the coreboot project. -/ This file is part of the coreboot project / -/ This file is part of the coreboot project. / -;## This file is part of the coreboot project. -# This file is part of the coreboot project. It originated in the - This file is part of the coreinfo project. -## This file is part of the coreinfo project. - * This file is part of the depthcharge project. -/* This file is part of the depthcharge project. / -/ This file is part of the ectool project. / - This file is part of the GNU C Library. - * This file is part of the libpayload project. -## This file is part of the libpayload project. -/* This file is part of the Linux kernel. / -## This file is part of the superiotool project. -/ This file is part of the superiotool project / -/ This file is part of uio_usbdebug */ Change-Id: I82d872b3b337388c93d5f5bf704e9ee9e53ab3a9 Signed-off-by: Patrick Georgi <pgeorgi@google.com> Reviewed-on: https://review.coreboot.org/c/coreboot/+/41194 Reviewed-by: HAOUAS Elyes <ehaouas@noos.fr> Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
2020-03-06	src/arch/riscv: Convert to SPDX license header	Patrick Georgi
	This also drops individual copyright notices, all mentioned authors in that part of the tree are listed in AUTHORS. Change-Id: I770c1afd9b68a40ec0e69818f24b5ef3ad4f1d35 Signed-off-by: Patrick Georgi <pgeorgi@google.com> Reviewed-on: https://review.coreboot.org/c/coreboot/+/39283 Tested-by: build bot (Jenkins) <no-reply@coreboot.org> Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net> Reviewed-by: HAOUAS Elyes <ehaouas@noos.fr>
2019-08-03	riscv: add support for OpenSBI	Xiang Wang
	Call OpenSBI in M-Mode and use it to set up SBI and to lockdown the platform. It will also jump to the specified payload when done. This behaviour is similar to BL31 on aarch31. The payload is 41KiB in size on qemu. Tested on qemu-riscv: Required to boot a kernel as OpenSBI's instruction emulation feature is required on that virtual machine. Tested on SiFive/unleashed: The earlycon is working. No console after regular serial driver should take over, which might be related to kernel config. Change-Id: I2a178595bd2aa2e1f114cbc69e8eadd46955b54d Signed-off-by: Xiang Wang <merle@hardenedlinux.org> Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com> Reviewed-on: https://review.coreboot.org/c/coreboot/+/32394 Tested-by: build bot (Jenkins) <no-reply@coreboot.org> Reviewed-by: Philipp Deppenwiese <zaolin.daisuki@gmail.com>
2019-06-23	riscv: use mret to invoke M-mode payload and disable interrupts	Xiang Wang
	Fixes a logic error that sets MPIE, but didn't use mret to return to the payload. This left MIE set to an undefined value. Now all modes are handled the same way: - Trap vector base address point to the payload - Disable Interrupt - Return to payload using mret TEST=Run an M-mode payload Change-Id: Iaab595f916949c57104ec00f8b06ea047fe76bba Signed-off-by: Xiang Wang <wxjstz@126.com> Reviewed-on: https://review.coreboot.org/c/coreboot/+/33462 Reviewed-by: Philipp Hug <philipp@hug.cx> Reviewed-by: Patrick Rudolph <patrick.rudolph@9elements.com> Reviewed-by: Patrick Rudolph <siro@das-labor.org> Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
2019-02-09	riscv: Use correct argument in a1 when invoking payload	Philipp Hug
	Fix a bug introduced by: 820dcfceb3901dbb00bb90c876e374126ca14e20 riscv: Simplify payload handling Put fdt into a1 correctly. Change-Id: I0dea7b88fde9d9a7365cb366917747d8110b9159 Signed-off-by: Philipp Hug <philipp@hug.cx> Reviewed-on: https://review.coreboot.org/c/31287 Reviewed-by: ron minnich <rminnich@gmail.com> Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
2019-02-02	riscv: Simplify payload handling	Xiang Wang
	1. Simplify payload code and convert it to C 2. Save the FDT pointer to HLS (hart-local storage). 3. Don't use mscratch to pass FDT pointer as it is used for exception handling. Change-Id: I32bf2a99e07a65358a7f19b899259f0816eb45e8 Signed-off-by: Xiang Wang <wxjstz@126.com> Signed-off-by: Philipp Hug <philipp@hug.cx> Reviewed-on: https://review.coreboot.org/c/31179 Reviewed-by: ron minnich <rminnich@gmail.com> Tested-by: build bot (Jenkins) <no-reply@coreboot.org>