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linux-user/elfload: Simplify vma_dump_size

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Use the flags that we've already saved in order to test
accessibility.  Use g2h_untagged and compare guest memory
directly instead of copy_from_user.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Richard Henderson 2024-02-27 06:47:49 -10:00
parent b4c7ab816b
commit 1928d50bec
1 changed files with 10 additions and 24 deletions
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34
linux-user/elfload.c
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@ -4166,37 +4166,23 @@ static int vma_get_mapping_count(const struct mm_struct *mm)
*/
static abi_ulong vma_dump_size(const struct vm_area_struct *vma)
{
/* if we cannot even read the first page, skip it */
if (!access_ok_untagged(VERIFY_READ, vma->vma_start, TARGET_PAGE_SIZE))
return (0);
/* The area must be readable. */
if (!(vma->vma_flags & PROT_READ)) {
return 0;
}
/*
* Usually we don't dump executable pages as they contain
* non-writable code that debugger can read directly from
* target library etc. However, thread stacks are marked
* also executable so we read in first page of given region
* and check whether it contains elf header. If there is
* no elf header, we dump it.
* target library etc. If there is no elf header, we dump it.
*/
if (vma->vma_flags & PROT_EXEC) {
char page[TARGET_PAGE_SIZE];
if (copy_from_user(page, vma->vma_start, sizeof (page))) {
return 0;
}
if ((page[EI_MAG0] == ELFMAG0) &&
(page[EI_MAG1] == ELFMAG1) &&
(page[EI_MAG2] == ELFMAG2) &&
(page[EI_MAG3] == ELFMAG3)) {
/*
* Mappings are possibly from ELF binary. Don't dump
* them.
*/
return (0);
}
if (!(vma->vma_flags & PROT_WRITE) &&
(vma->vma_flags & PROT_EXEC) &&
memcmp(g2h_untagged(vma->vma_start), ELFMAG, SELFMAG) == 0) {
return 0;
}
return (vma->vma_end - vma->vma_start);
return vma->vma_end - vma->vma_start;
}
static int vma_walker(void *priv, target_ulong start, target_ulong end,