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arm64: hw_breakpoint: fix watchpoint matching for tagged pointers
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>
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@ -106,9 +106,9 @@ static inline void set_fs(mm_segment_t fs)
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})
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/*
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* When dealing with data aborts or instruction traps we may end up with
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* a tagged userland pointer. Clear the tag to get a sane pointer to pass
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* on to access_ok(), for instance.
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* When dealing with data aborts, watchpoints, or instruction traps we may end
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* up with a tagged userland pointer. Clear the tag to get a sane pointer to
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* pass on to access_ok(), for instance.
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*/
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#define untagged_addr(addr) sign_extend64(addr, 55)
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@ -36,6 +36,7 @@
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#include <asm/traps.h>
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#include <asm/cputype.h>
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#include <asm/system_misc.h>
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#include <asm/uaccess.h>
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/* Breakpoint currently in use for each BRP. */
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static DEFINE_PER_CPU(struct perf_event *, bp_on_reg[ARM_MAX_BRP]);
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@ -721,6 +722,8 @@ static u64 get_distance_from_watchpoint(unsigned long addr, u64 val,
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u64 wp_low, wp_high;
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u32 lens, lene;
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addr = untagged_addr(addr);
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lens = __ffs(ctrl->len);
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lene = __fls(ctrl->len);
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