linux_dsm_epyc7002/arch/riscv/include/asm/elf.h
Christoph Hellwig 6bd33e1ece riscv: add nommu support
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>
2019-11-17 15:17:39 -08:00

72 lines
1.9 KiB
C

/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
* Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
* Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
* Copyright (C) 2012 Regents of the University of California
*/
#ifndef _ASM_RISCV_ELF_H
#define _ASM_RISCV_ELF_H
#include <uapi/asm/elf.h>
#include <asm/auxvec.h>
#include <asm/byteorder.h>
/*
* These are used to set parameters in the core dumps.
*/
#define ELF_ARCH EM_RISCV
#ifdef CONFIG_64BIT
#define ELF_CLASS ELFCLASS64
#else
#define ELF_CLASS ELFCLASS32
#endif
#define ELF_DATA ELFDATA2LSB
/*
* This is used to ensure we don't load something for the wrong architecture.
*/
#define elf_check_arch(x) ((x)->e_machine == EM_RISCV)
#define CORE_DUMP_USE_REGSET
#define ELF_EXEC_PAGESIZE (PAGE_SIZE)
/*
* This is the location that an ET_DYN program is loaded if exec'ed. Typical
* use of this is to invoke "./ld.so someprog" to test out a new version of
* the loader. We need to make sure that it is out of the way of the program
* that it will "exec", and that there is sufficient room for the brk.
*/
#define ELF_ET_DYN_BASE ((TASK_SIZE / 3) * 2)
/*
* This yields a mask that user programs can use to figure out what
* instruction set this CPU supports. This could be done in user space,
* but it's not easy, and we've already done it here.
*/
#define ELF_HWCAP (elf_hwcap)
extern unsigned long elf_hwcap;
/*
* This yields a string that ld.so will use to load implementation
* specific libraries for optimization. This is more specific in
* intent than poking at uname or /proc/cpuinfo.
*/
#define ELF_PLATFORM (NULL)
#ifdef CONFIG_MMU
#define ARCH_DLINFO \
do { \
NEW_AUX_ENT(AT_SYSINFO_EHDR, \
(elf_addr_t)current->mm->context.vdso); \
} while (0)
#define ARCH_HAS_SETUP_ADDITIONAL_PAGES
struct linux_binprm;
extern int arch_setup_additional_pages(struct linux_binprm *bprm,
int uses_interp);
#endif /* CONFIG_MMU */
#endif /* _ASM_RISCV_ELF_H */