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| author | Kirill A. Shutemov <kirill.shutemov@linux.intel.com> | 2018-05-16 11:01:29 +0300 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2018-05-16 13:15:13 +0300 |
| commit | 589bb62be316401603453c7d2d3c60ad8b9c3cf3 (patch) | |
| tree | ab530c19d1e742bdcde35a7866ab0827e9ecee15 /arch/x86/boot/compressed/head_64.S | |
| parent | 5c9b0b1c49881c680d4a56b9d9e03dfb3160fd4d (diff) | |
| download | linux-589bb62be316401603453c7d2d3c60ad8b9c3cf3.tar.xz | |
x86/boot/compressed/64: Fix moving page table out of trampoline memory
cleanup_trampoline() relocates the top-level page table out of
trampoline memory. We use 'top_pgtable' as our new top-level page table.
But if the 'top_pgtable' would be referenced from C in a usual way,
the address of the table will be calculated relative to RIP.
After kernel gets relocated, the address will be in the middle of
decompression buffer and the page table may get overwritten.
This leads to a crash.
We calculate the address of other page tables relative to the relocation
address. It makes them safe. We should do the same for 'top_pgtable'.
Calculate the address of 'top_pgtable' in assembly and pass down to
cleanup_trampoline().
Move the page table to .pgtable section where the rest of page tables
are. The section is @nobits so we save 4k in kernel image.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Fixes: e9d0e6330eb8 ("x86/boot/compressed/64: Prepare new top-level page table for trampoline")
Link: http://lkml.kernel.org/r/20180516080131.27913-3-kirill.shutemov@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/boot/compressed/head_64.S')
| -rw-r--r-- | arch/x86/boot/compressed/head_64.S | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S index d17af6a4bfc9..8169e8b7a4dc 100644 --- a/arch/x86/boot/compressed/head_64.S +++ b/arch/x86/boot/compressed/head_64.S @@ -389,10 +389,14 @@ trampoline_return: /* * cleanup_trampoline() would restore trampoline memory. * + * RDI is address of the page table to use instead of page table + * in trampoline memory (if required). + * * RSI holds real mode data and needs to be preserved across * this function call. */ pushq %rsi + leaq top_pgtable(%rbx), %rdi call cleanup_trampoline popq %rsi @@ -691,3 +695,10 @@ boot_stack_end: .balign 4096 pgtable: .fill BOOT_PGT_SIZE, 1, 0 + +/* + * The page table is going to be used instead of page table in the trampoline + * memory. + */ +top_pgtable: + .fill PAGE_SIZE, 1, 0 |