Commit 7dcd9dd8 authored by Kristina Martsenko's avatar Kristina Martsenko Committed by Catalin Marinas
Browse files

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: d50240a5

 ("arm64: mm: permit use of tagged pointers at EL0")
Cc: <stable@vger.kernel.org> # 3.12.x-
Acked-by: Mark Rutland's avatarMark Rutland <mark.rutland@arm.com>
Acked-by: default avatarWill Deacon <will.deacon@arm.com>
Signed-off-by: Kristina Martsenko's avatarKristina Martsenko <kristina.martsenko@arm.com>
Signed-off-by: Catalin Marinas's avatarCatalin Marinas <catalin.marinas@arm.com>
parent 81cddd65
......@@ -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)
......
......@@ -36,6 +36,7 @@
#include <asm/traps.h>
#include <asm/cputype.h>
#include <asm/system_misc.h>
#include <asm/uaccess.h>
/* Breakpoint currently in use for each BRP. */
static DEFINE_PER_CPU(struct perf_event *, bp_on_reg[ARM_MAX_BRP]);
......@@ -721,6 +722,8 @@ static u64 get_distance_from_watchpoint(unsigned long addr, u64 val,
u64 wp_low, wp_high;
u32 lens, lene;
addr = untagged_addr(addr);
lens = __ffs(ctrl->len);
lene = __fls(ctrl->len);
......
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