cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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riscv-stub.c (3405B)

      1// SPDX-License-Identifier: GPL-2.0
      2/*
      3 * Copyright (C) 2020 Western Digital Corporation or its affiliates.
      4 */
      5
      6#include <linux/efi.h>
      7#include <linux/libfdt.h>
      8
      9#include <asm/efi.h>
     10#include <asm/sections.h>
     11
     12#include "efistub.h"
     13
     14/*
     15 * RISC-V requires the kernel image to placed 2 MB aligned base for 64 bit and
     16 * 4MB for 32 bit.
     17 */
     18#ifdef CONFIG_64BIT
     19#define MIN_KIMG_ALIGN		SZ_2M
     20#else
     21#define MIN_KIMG_ALIGN		SZ_4M
     22#endif
     23
     24typedef void __noreturn (*jump_kernel_func)(unsigned long, unsigned long);
     25
     26static unsigned long hartid;
     27
     28static int get_boot_hartid_from_fdt(void)
     29{
     30	const void *fdt;
     31	int chosen_node, len;
     32	const fdt32_t *prop;
     33
     34	fdt = get_efi_config_table(DEVICE_TREE_GUID);
     35	if (!fdt)
     36		return -EINVAL;
     37
     38	chosen_node = fdt_path_offset(fdt, "/chosen");
     39	if (chosen_node < 0)
     40		return -EINVAL;
     41
     42	prop = fdt_getprop((void *)fdt, chosen_node, "boot-hartid", &len);
     43	if (!prop || len != sizeof(u32))
     44		return -EINVAL;
     45
     46	hartid = fdt32_to_cpu(*prop);
     47	return 0;
     48}
     49
     50static efi_status_t get_boot_hartid_from_efi(void)
     51{
     52	efi_guid_t boot_protocol_guid = RISCV_EFI_BOOT_PROTOCOL_GUID;
     53	struct riscv_efi_boot_protocol *boot_protocol;
     54	efi_status_t status;
     55
     56	status = efi_bs_call(locate_protocol, &boot_protocol_guid, NULL,
     57			     (void **)&boot_protocol);
     58	if (status != EFI_SUCCESS)
     59		return status;
     60	return efi_call_proto(boot_protocol, get_boot_hartid, &hartid);
     61}
     62
     63efi_status_t check_platform_features(void)
     64{
     65	efi_status_t status;
     66	int ret;
     67
     68	status = get_boot_hartid_from_efi();
     69	if (status != EFI_SUCCESS) {
     70		ret = get_boot_hartid_from_fdt();
     71		if (ret) {
     72			efi_err("Failed to get boot hartid!\n");
     73			return EFI_UNSUPPORTED;
     74		}
     75	}
     76	return EFI_SUCCESS;
     77}
     78
     79void __noreturn efi_enter_kernel(unsigned long entrypoint, unsigned long fdt,
     80				 unsigned long fdt_size)
     81{
     82	unsigned long stext_offset = _start_kernel - _start;
     83	unsigned long kernel_entry = entrypoint + stext_offset;
     84	jump_kernel_func jump_kernel = (jump_kernel_func)kernel_entry;
     85
     86	/*
     87	 * Jump to real kernel here with following constraints.
     88	 * 1. MMU should be disabled.
     89	 * 2. a0 should contain hartid
     90	 * 3. a1 should DT address
     91	 */
     92	csr_write(CSR_SATP, 0);
     93	jump_kernel(hartid, fdt);
     94}
     95
     96efi_status_t handle_kernel_image(unsigned long *image_addr,
     97				 unsigned long *image_size,
     98				 unsigned long *reserve_addr,
     99				 unsigned long *reserve_size,
    100				 efi_loaded_image_t *image,
    101				 efi_handle_t image_handle)
    102{
    103	unsigned long kernel_size = 0;
    104	unsigned long preferred_addr;
    105	efi_status_t status;
    106
    107	kernel_size = _edata - _start;
    108	*image_addr = (unsigned long)_start;
    109	*image_size = kernel_size + (_end - _edata);
    110
    111	/*
    112	 * RISC-V kernel maps PAGE_OFFSET virtual address to the same physical
    113	 * address where kernel is booted. That's why kernel should boot from
    114	 * as low as possible to avoid wastage of memory. Currently, dram_base
    115	 * is occupied by the firmware. So the preferred address for kernel to
    116	 * boot is next aligned address. If preferred address is not available,
    117	 * relocate_kernel will fall back to efi_low_alloc_above to allocate
    118	 * lowest possible memory region as long as the address and size meets
    119	 * the alignment constraints.
    120	 */
    121	preferred_addr = MIN_KIMG_ALIGN;
    122	status = efi_relocate_kernel(image_addr, kernel_size, *image_size,
    123				     preferred_addr, MIN_KIMG_ALIGN, 0x0);
    124
    125	if (status != EFI_SUCCESS) {
    126		efi_err("Failed to relocate kernel\n");
    127		*image_size = 0;
    128	}
    129	return status;
    130}