Use the original FAR_EL1 value when an MTE tag check fault occurs,
if ARM64_MTE_FAR is supported.
This allows reports to include not only the logical tag (memory tag)
but also the address tag information.
Applications that require this information should install a signal handler with
the SA_EXPOSE_TAGBITS flag.
While this introduces a minor ABI change,
most applications do not set this flag and therefore will not be affected.
Signed-off-by: Yeoreum Yun <yeoreum.yun@xxxxxxx>
---
arch/arm64/mm/fault.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index ec0a337891dd..f21d972f99b1 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -837,9 +837,12 @@ static int do_tag_check_fault(unsigned long far, unsigned long esr,
/*
* The architecture specifies that bits 63:60 of FAR_EL1 are UNKNOWN
* for tag check faults. Set them to corresponding bits in the untagged
- * address.
+ * address if ARM64_MTE_FAR isn't supported.
+ * Otherwise, bits 63:60 of FAR_EL1 are KNOWN.
*/
- far = (__untagged_addr(far) & ~MTE_TAG_MASK) | (far & MTE_TAG_MASK);
+ if (!cpus_have_cap(ARM64_MTE_FAR))
+ far = (__untagged_addr(far) & ~MTE_TAG_MASK) | (far & MTE_TAG_MASK);
+
do_bad_area(far, esr, regs);
return 0;
}
--
LEVI:{C3F47F37-75D8-414A-A8BA-3980EC8A46D7}
