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arch/arm64: Map a region that does not start at a page table boundary.

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create_region() mapped up to ENTRIES_PER_PGT pages through one final
level table, from whatever address the region started at.  The text
region starts one page after the reserved area, so a region that
crossed the end of the table wrapped around and mapped its last pages
over the first entries of the same table.  In a program with more than
about 2 MB of text, the reserved area became read-only and the kernel
faulted in umm_initialize().

Walk the region one final level table at a time.

Assisted-by: Claude Code:claude-opus-5-5
Signed-off-by: Marco Casaroli <marco.casaroli@gmail.com>
This commit is contained in:
Marco Casaroli 2026-10-09 00:17:03 +02:00 • committed by Alan C. Assis
parent 3515e44845
commit 55cd85c9ab
1 changed files with 26 additions and 14 deletions
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40
arch/arm64/src/common/arm64_addrenv_mmu.c
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@ -267,14 +267,13 @@ static int create_region(arch_addrenv_t *addrenv, uintptr_t vaddr,
uintptr_t ptlast;
uintptr_t ptprev;
uintptr_t paddr;
uintptr_t vend;
uintptr_t tend;
uint32_t ptlevel;
int npages;
int nmapped;
int i;
int j;
nmapped = 0;
npages = MM_NPAGES(size);
vend = vaddr + ((uintptr_t)npages << MM_PGSHIFT);
ptlevel = MMU_PGT_LEVEL_MAX - 1;
ptprev = arm64_pgvaddr(addrenv->spgtables[ptlevel]);
@ -284,8 +283,19 @@ static int create_region(arch_addrenv_t *addrenv, uintptr_t vaddr,
/* Begin allocating memory for the page tables */
for (i = 0; i < npages; i += ENTRIES_PER_PGT)
while (vaddr < vend)
{
/* One final level table maps ENTRIES_PER_PGT pages. The region need
* not start at the beginning of a table, so stop at the end of this
* one and look up the next.
*/
tend = (vaddr | ((ENTRIES_PER_PGT << MM_PGSHIFT) - 1)) + 1;
if (tend > vend || tend == 0)
{
tend = vend;
}
/* Get the current final level entry corresponding to this vaddr */
paddr = mmu_pte_to_paddr(mmu_ln_getentry(ptlevel, ptprev, vaddr));
@ -313,13 +323,7 @@ static int create_region(arch_addrenv_t *addrenv, uintptr_t vaddr,
/* Then allocate memory for the region data */
for (j = 0;
#ifdef CONFIG_PAGING
j < 1;
#else
j < ENTRIES_PER_PGT && nmapped < size;
#endif
j++)
do
{
paddr = mm_pgalloc(1);
if (!paddr)
@ -334,9 +338,17 @@ static int create_region(arch_addrenv_t *addrenv, uintptr_t vaddr,
/* Then map the virtual address to the physical address */
mmu_ln_setentry(ptlevel + 1, ptlast, paddr, vaddr, mmuflags);
nmapped += MM_PGSIZE;
vaddr += MM_PGSIZE;
vaddr += MM_PGSIZE;
}
#ifdef CONFIG_PAGING
while (0);
/* Only the first page of each table; the rest come on demand */
vaddr = tend;
#else
while (vaddr < tend);
#endif
}
/* Synchronize data and instruction pipelines */