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Subject[tip:x86/boot] x86/boot/compressed/64: Fix trampoline page table address calculation
Commit-ID:  30bbf728ba91b1e8b0e539126cd105ad7e2fa16a
Gitweb: https://git.kernel.org/tip/30bbf728ba91b1e8b0e539126cd105ad7e2fa16a
Author: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
AuthorDate: Fri, 18 May 2018 13:35:22 +0300
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Sat, 19 May 2018 11:56:57 +0200

x86/boot/compressed/64: Fix trampoline page table address calculation

Hugh noticied that we calculate the address of the trampoline page table
incorrectly in cleanup_trampoline().

TRAMPOLINE_32BIT_PGTABLE_OFFSET has to be divided by sizeof(unsigned long),
since trampoline_32bit is an 'unsigned long' pointer.

TRAMPOLINE_32BIT_PGTABLE_OFFSET is zero so the bug doesn't have a
visible effect.

Reported-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
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/20180518103528.59260-2-kirill.shutemov@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/boot/compressed/pgtable_64.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/boot/compressed/pgtable_64.c b/arch/x86/boot/compressed/pgtable_64.c
index a362fa0b849c..23707e1da1ff 100644
--- a/arch/x86/boot/compressed/pgtable_64.c
+++ b/arch/x86/boot/compressed/pgtable_64.c
@@ -130,7 +130,7 @@ void cleanup_trampoline(void *pgtable)
{
void *trampoline_pgtable;

- trampoline_pgtable = trampoline_32bit + TRAMPOLINE_32BIT_PGTABLE_OFFSET;
+ trampoline_pgtable = trampoline_32bit + TRAMPOLINE_32BIT_PGTABLE_OFFSET / sizeof(unsigned long);

/*
* Move the top level page table out of trampoline memory,
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