acrn-hypervisor/hypervisor/boot/reloc.c

127 lines
3.1 KiB
C

/*
* Copyright (C) 2018 Intel Corporation. All rights reserved.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
#include <types.h>
#include <reloc.h>
#include <ld_sym.h>
#ifdef CONFIG_RELOC
#define DT_NULL 0U /* end of .dynamic section */
#define DT_RELA 7U /* relocation table */
#define DT_RELASZ 8U /* size of reloc table */
#define DT_RELAENT 9U /* size of one entry */
#define R_X86_64_RELATIVE 8UL
struct Elf64_Dyn {
uint64_t d_tag;
uint64_t d_ptr;
};
struct Elf64_Rel {
uint64_t r_offset;
uint64_t r_info;
uint64_t reserved;
};
#endif
static inline uint64_t elf64_r_type(uint64_t i)
{
return (i & 0xffffffffUL);
}
/* get the delta between CONFIG_HV_RAM_START and the actual load address */
uint64_t get_hv_image_delta(void)
{
uint64_t addr;
asm volatile (" call 0f\n"
"0: pop %%rax\n"
" sub $0b, %%rax\n"
" mov %%rax, %0\n"
: "=m" (addr)
:
: "%rax");
return addr;
}
/* get the actual Hypervisor load address (HVA) */
uint64_t get_hv_image_base(void)
{
return (get_hv_image_delta() + CONFIG_HV_RAM_START);
}
void relocate(void)
{
#ifdef CONFIG_RELOC
struct Elf64_Dyn *dyn;
struct Elf64_Rel *start = NULL, *end = NULL;
uint64_t delta, size = 0;
uint64_t trampoline_end;
uint64_t primary_32_start, primary_32_end;
uint64_t *addr;
/* get the delta that needs to be patched */
delta = get_hv_image_delta();
if (delta != 0U) {
/* Look for the descriptoin of relocation sections */
for (dyn = (struct Elf64_Dyn *)_DYNAMIC; dyn->d_tag != DT_NULL; dyn++) {
switch (dyn->d_tag) {
case DT_RELA:
start = (struct Elf64_Rel *)(dyn->d_ptr + delta);
break;
case DT_RELASZ:
end = (struct Elf64_Rel *)start + dyn->d_ptr;
break;
case DT_RELAENT:
size = dyn->d_ptr;
break;
default:
/* if no RELA/RELASZ found, both start and end will be initialized to NULL, and later while loop won't be executed */
break;
}
}
/*
* Need to subtract the relocation delta to get the correct
* absolute addresses
*/
trampoline_end = (uint64_t)(&ld_trampoline_end) - delta;
primary_32_start = (uint64_t)(&cpu_primary_start_32) - delta;
primary_32_end = (uint64_t)(&cpu_primary_start_64) - delta;
while (start < end) {
if ((elf64_r_type(start->r_info)) == R_X86_64_RELATIVE) {
addr = (uint64_t *)(delta + start->r_offset);
/*
* we won't fixup any trampoline.S and cpu_primary.S here
* for a number of reasons:
*
* - trampoline code itself takes another relocation,
* so any entries for trampoline symbols can't be fixed up
* through .rela sections
* - In cpu_primary.S, the 32 bits code doesn't need relocation
* - Linker option "-z noreloc-overflow" could force R_X86_32
* to R_X86_64 in the relocation sections, which could make
* the fixed up code dirty. Even if relocation for 32 bits
* is needed in the future, it's recommended to do it
* explicitly in the assembly code to avoid confusion.
*/
if ((start->r_offset > trampoline_end) &&
((start->r_offset < primary_32_start) ||
(start->r_offset > primary_32_end))) {
*addr += delta;
}
}
start = (struct Elf64_Rel *)((char *)start + size);
}
}
#endif
}