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| author | Michael Ellerman <mpe@ellerman.id.au> | 2021-08-31 23:51:51 +1000 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2021-09-01 16:52:53 +1000 |
| commit | b14b8b1ed0e15b8f43fba9c25654278a31ee3c2f (patch) | |
| tree | 0a91fac7802cfaee69e85112aaaa285abf9d1404 /arch/powerpc/mm | |
| parent | 1d78dfde33a02da1d816279c2e3452978b7abd39 (diff) | |
powerpc/ptdump: Fix generic ptdump for 64-bit
Since the conversion to generic ptdump we see crashes on 64-bit:
BUG: Unable to handle kernel data access on read at 0xc0eeff7f00000000
Faulting instruction address: 0xc00000000045e5fc
Oops: Kernel access of bad area, sig: 11 [#1]
...
NIP __walk_page_range+0x2bc/0xce0
LR __walk_page_range+0x240/0xce0
Call Trace:
__walk_page_range+0x240/0xce0 (unreliable)
walk_page_range_novma+0x74/0xb0
ptdump_walk_pgd+0x98/0x170
ptdump_check_wx+0x88/0xd0
mark_rodata_ro+0x48/0x80
kernel_init+0x74/0x1a0
ret_from_kernel_thread+0x5c/0x64
What's happening is that have walked off the end of the kernel page
tables, and started dereferencing junk values.
That happens because we initialised the ptdump_range to span all the way
up to 0xffffffffffffffff:
static struct ptdump_range ptdump_range[] __ro_after_init = {
{TASK_SIZE_MAX, ~0UL},
But the kernel page tables don't span that far. So on 64-bit set the end
of the range to be the address immediately past the end of the kernel
page tables, to limit the page table walk to valid addresses.
Fixes: e084728393a5 ("powerpc/ptdump: Convert powerpc to GENERIC_PTDUMP")
Reported-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210831135151.886620-1-mpe@ellerman.id.au
Diffstat (limited to 'arch/powerpc/mm')
| -rw-r--r-- | arch/powerpc/mm/ptdump/ptdump.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/powerpc/mm/ptdump/ptdump.c b/arch/powerpc/mm/ptdump/ptdump.c index 2d80d775d15e..bf251191e78d 100644 --- a/arch/powerpc/mm/ptdump/ptdump.c +++ b/arch/powerpc/mm/ptdump/ptdump.c @@ -359,6 +359,8 @@ static int __init ptdump_init(void) ptdump_range[0].start = KERN_VIRT_START; else ptdump_range[0].start = PAGE_OFFSET; + + ptdump_range[0].end = PAGE_OFFSET + (PGDIR_SIZE * PTRS_PER_PGD); #endif populate_markers(); |