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arm64: hw_breakpoint: fix watchpoint matching for tagged pointers

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When we take a watchpoint exception, the address that triggered the
watchpoint is found in FAR_EL1. We compare it to the address of each
configured watchpoint to see which one was hit.

The configured watchpoint addresses are untagged, while the address in
FAR_EL1 will have an address tag if the data access was done using a
tagged address. The tag needs to be removed to compare the address to
the watchpoints.

Currently we don't remove it, and as a result can report the wrong
watchpoint as being hit (specifically, always either the highest TTBR0
watchpoint or lowest TTBR1 watchpoint). This patch removes the tag.

Fixes: d50240a5f6 ("arm64: mm: permit use of tagged pointers at EL0")
Cc: <stable@vger.kernel.org> # 3.12.x-
Acked-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Kristina Martsenko
2017-05-03 16:37:46 +01:00
committed by Catalin Marinas
parent 81cddd65b5
commit 7dcd9dd8ce
2 changed files with 6 additions and 3 deletions
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6
arch/arm64/include/asm/uaccess.h
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@@ -106,9 +106,9 @@ static inline void set_fs(mm_segment_t fs)
})
/*
* When dealing with data aborts or instruction traps we may end up with
* a tagged userland pointer. Clear the tag to get a sane pointer to pass
* on to access_ok(), for instance.
* When dealing with data aborts, watchpoints, or instruction traps we may end
* up with a tagged userland pointer. Clear the tag to get a sane pointer to
* pass on to access_ok(), for instance.
*/
#define untagged_addr(addr) sign_extend64(addr, 55)