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https://github.com/projectacrn/acrn-hypervisor.git
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1dee977429
This patch implements relocation support for ACRN RISC-V to enable position-independent execution. The hypervisor can now be loaded at any physical address and will automatically relocate itself at runtime. Key changes: - Add relocate() function to process R_RISCV_RELATIVE relocations in .rela sections during early boot - Implement arch_get_hv_image_delta() to calculate the load address offset from the configured base address - Add relocation processing in cpu_entry.S before jumping to C code - Update linker script to include .rela sections for relocation data - Define R_RISCV_RELATIVE relocation type and linker symbol definitions Tracked-On: #8825 Signed-off-by: Jian Jun Chen <jian.jun.chen@intel.com> Acked-by: Wang, Yu1 <yu1.wang@intel.com>
74 lines
1.6 KiB
C
74 lines
1.6 KiB
C
/*
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* Copyright (C) 2025 Intel Corporation.
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*
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* SPDX-License-Identifier: BSD-3-Clause
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*/
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#include <types.h>
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#include <reloc.h>
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/* get the delta between CONFIG_HV_RAM_START and the actual load address */
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uint64_t arch_get_hv_image_delta(void)
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{
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uint64_t delta;
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asm volatile (
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"lla %0, _start\n"
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"li t1, %1\n"
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"sub %0, %0, t1\n"
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: "=r" (delta)
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: "i" ((uint64_t)CONFIG_HV_RAM_START)
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: "t1");
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return delta;
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}
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#ifdef CONFIG_RELOC
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void relocate(struct Elf64_Dyn *dynamic)
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{
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struct Elf64_Dyn *dyn;
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struct Elf64_Rel *entry = NULL;
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uint8_t *rela_start = NULL, *rela_end = NULL;
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uint64_t rela_size = 0;
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uint64_t delta, entry_size = 0;
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uint64_t *addr;
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/* get the delta that needs to be patched */
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delta = get_hv_image_delta();
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/* Look for the descriptoin of relocation sections */
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for (dyn = (struct Elf64_Dyn *)dynamic;
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dyn->d_tag != DT_NULL; dyn++) {
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switch (dyn->d_tag) {
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case DT_RELA:
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rela_start = (uint8_t *)(dyn->d_ptr + delta);
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break;
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case DT_RELASZ:
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rela_size = dyn->d_ptr;
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break;
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case DT_RELAENT:
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entry_size = dyn->d_ptr;
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break;
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default:
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/* if no RELA/RELASZ found, both start and end will be
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* initialized to NULL, and later while loop won't be executed
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*/
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break;
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}
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}
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/*
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* Need to subtract the relocation delta to get the correct
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* absolute addresses
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*/
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rela_end = rela_start + rela_size;
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while (rela_start < rela_end) {
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entry = (struct Elf64_Rel *)rela_start;
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if ((elf64_r_type(entry->r_info)) == R_RISCV_RELATIVE) {
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addr = (uint64_t *)(delta + entry->r_offset);
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*addr += (entry->r_addend + delta);
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}
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rela_start += entry_size;
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}
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}
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#endif /* CONFIG_RELOC */
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