4.9-stable review patch. If anyone has any objections, please let me know.
------------------ From: Kristina Martsenko <[email protected]> commit 7dcd9dd8cebe9fa626af7e2358d03a37041a70fb upstream. This backport has a small difference from the upstream commit: - The address tag is removed in watchpoint_handler() instead of get_distance_from_watchpoint(), because 4.9 does not have commit fdfeff0f9e3d ("arm64: hw_breakpoint: Handle inexact watchpoint addresses"). Original patch description: 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: d50240a5f6ce ("arm64: mm: permit use of tagged pointers at EL0") Acked-by: Mark Rutland <[email protected]> Acked-by: Will Deacon <[email protected]> Signed-off-by: Kristina Martsenko <[email protected]> Signed-off-by: Catalin Marinas <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- arch/arm64/include/asm/uaccess.h | 6 +++--- arch/arm64/kernel/hw_breakpoint.c | 3 ++- 2 files changed, 5 insertions(+), 4 deletions(-) --- a/arch/arm64/include/asm/uaccess.h +++ b/arch/arm64/include/asm/uaccess.h @@ -105,9 +105,9 @@ static inline void set_fs(mm_segment_t f }) /* - * 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) --- a/arch/arm64/kernel/hw_breakpoint.c +++ b/arch/arm64/kernel/hw_breakpoint.c @@ -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]); @@ -696,7 +697,7 @@ static int watchpoint_handler(unsigned l /* Check if the watchpoint value matches. */ val = read_wb_reg(AARCH64_DBG_REG_WVR, i); - if (val != (addr & ~alignment_mask)) + if (val != (untagged_addr(addr) & ~alignment_mask)) goto unlock; /* Possible match, check the byte address select to confirm. */
