Re: [Crash-utility] using crash for ARM
2012/10/4 Mika Westerberg <mika.westerberg(a)iki.fi>:
The unity-mapped region is mapped using 1MB pages. However, we
actually have
(when using the Linux ARM 2-level translation scheme):
see arch/arm/include/asm/pgtable-2level.h:
#define PMD_SHIFT 21
#define PGDIR_SHIFT 21
#define PTRS_PER_PGD 2048
So we have 2048 entries in a PGD instead of 4096 making a PGD entry an array
of "two pointers".
Anyway as you and Paawan suggested it looks like a bug - we always use the
first entry instead of the second given that bit 20 is set in the virtual
address.
Isn't the problem actually that we read the section entry wrong?
The following (and attached) is the fix I've been using for this.
Rabin
diff --git a/arm.c b/arm.c
index 5930c02..4e7b6dc 100644
--- a/arm.c
+++ b/arm.c
@@ -957,12 +957,14 @@ arm_vtop(ulong vaddr, ulong *pgd, physaddr_t
*paddr, int verbose)
MKSTR((ulong)page_middle)), pmd_pte);
if ((pmd_pte & PMD_TYPE_MASK) == PMD_TYPE_SECT) {
+ ulong sectionbase = pmd_pte & _SECTION_PAGE_MASK;
+
if (verbose) {
fprintf(fp, " PAGE: %s (1MB)\n\n",
mkstring(buf, VADDR_PRLEN, RJUST | LONG_HEX,
- MKSTR(PAGEBASE(pmd_pte))));
+ MKSTR(sectionbase)));
}
- *paddr = PAGEBASE(pmd_pte) + (vaddr & ~_SECTION_PAGE_MASK);
+ *paddr = sectionbase + (vaddr & ~_SECTION_PAGE_MASK);
return TRUE;
}
Attachments:
- 0001-fix-vtop-Section-handling.patch (application/octet-stream — 909 bytes)