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[libcpu][risc-v] 减少rv64 smart版本中mmu early map时的地址空间大小以防止cpu猜测执行到不存在的地址空间 #10332

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Merged
Rbb666 merged 2 commits into from
May 28, 2025
Merged

[libcpu][risc-v] 减少rv64 smart版本中mmu early map时的地址空间大小以防止cpu猜测执行到不存在的地址空间 #10332

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fb149aa
[libcpu][risc-v] fix:only map the 1GB space where the original code s…
zhangjing0303 Apr 3, 2025
84435a4
[libcpu][risc-v]:add comment for the round down of symb_pc
zhangjing0303 May 28, 2025
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12 changes: 7 additions & 5 deletions libcpu/risc-v/common64/mmu.c
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Original file line number Diff line number Diff line change
Expand Up @@ -691,11 +691,13 @@ void rt_hw_mem_setup_early(void)
* identical mapping,
* PC are still at lower region before relocating to high memory
*/
for (size_t i = 0; i < __SIZE(PPN0_BIT); i++)
{
early_pgtbl[i] = COMBINEPTE(ps, MMU_MAP_EARLY);
ps += L1_PAGE_SIZE;
}
rt_ubase_t pg_idx ;
/* Round down symb_pc to L1_PAGE_SIZE boundary to ensure proper page alignment.
* This is necessary because MMU operations work with page-aligned addresses, and
* make sure all the text region is mapped.*/
ps = (rt_ubase_t)symb_pc & (~(L1_PAGE_SIZE - 1));
pg_idx = GET_L1(ps);
early_pgtbl[pg_idx] = COMBINEPTE(ps, MMU_MAP_EARLY);

/* relocate text region */
__asm__ volatile("la %0, _start\n" : "=r"(ps));
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