[Crash-utility] [PATCH] ARM: fix segfault in page table read

[Rabin Vincent]

I have an ARM crash dump where the page tables have been corrupted.

crash segfaults while reading it because of a stack overflow due to recursion
in the page table read core:

readmem: e2efcde0, KVADDR, "module unwind table", 24, (ROE), 8600bc0>
    addr: e2efcde0  paddr: 22efcde0  cnt: 24
<readmem: bf006550, KVADDR, "module unwind index table", 8, (ROE), 9ccab28>
<readmem: c0004000, KVADDR, "pgd page", 16384, (FOE), 91c18e8>
    addr: c0004000  paddr: 4000  cnt: 4096
    addr: c0005000  paddr: 5000  cnt: 4096
    addr: c0006000  paddr: 6000  cnt: 4096
    addr: c0007000  paddr: 7000  cnt: 4096
<readmem: ed2d3000, KVADDR, "page table", 4096, (FOE), 91c58f0>
<readmem: ed2d3000, KVADDR, "page table", 4096, (FOE), 91c58f0>
<readmem: ed2d3000, KVADDR, "page table", 4096, (FOE), 91c58f0>
<readmem: ed2d3000, KVADDR, "page table", 4096, (FOE), 91c58f0>
<readmem: ed2d3000, KVADDR, "page table", 4096, (FOE), 91c58f0>
<readmem: ed2d3000, KVADDR, "page table", 4096, (FOE), 91c58f0>
etc till segfault

The problem appears to be that the ARM code is attempting to PTOV() the
physical address found in the page table and readmem() it as a KVADDR instead
of just directly reading it as a PHYSADDR.

Patch below.

Rabin

diff --git a/arm.c b/arm.c
index 5eb5649..4ca2fcd 100644
--- a/arm.c
+++ b/arm.c
@@ -979,9 +979,9 @@ arm_vtop(ulong vaddr, ulong *pgd, physaddr_t *paddr, int verbose)
 	/*
 	 * pte_offset_map(pmd, vaddr)
 	 */
-	page_table = (ulong *)PTOV(pmd_page_addr(pmd_pte)) + PTE_OFFSET(vaddr);
+	page_table = pmd_page_addr(pmd_pte) + PTE_OFFSET(vaddr);
 
-	FILL_PTBL(PAGEBASE(page_table), KVADDR, PAGESIZE());
+	FILL_PTBL(PAGEBASE(page_table), PHYSADDR, PAGESIZE());
 	pte = ULONG(machdep->ptbl + PAGEOFFSET(page_table));
 
 	if (verbose) {