On Thu, Jul 29, 2021 at 3:47 PM Sven Schnelle [off-list ref] wrote:

Alexander Potapenko [off-list ref] writes:

quoted

On Wed, Jul 28, 2021 at 9:03 PM Heiko Carstens [off-list ref] wrote:

quoted

From: Sven Schnelle <svens@linux.ibm.com>

s390 only reports the page address during a translation fault.
To make the kfence unit tests pass, add a function that might
be implemented by architectures to mask out address bits.

Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
---
 mm/kfence/kfence_test.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/mm/kfence/kfence_test.c b/mm/kfence/kfence_test.c
index 942cbc16ad26..eb6307c199ea 100644
--- a/mm/kfence/kfence_test.c
+++ b/mm/kfence/kfence_test.c

@@ -23,8 +23,15 @@
 #include <linux/tracepoint.h>
 #include <trace/events/printk.h>

+#include <asm/kfence.h>
+
 #include "kfence.h"

+/* May be overridden by <asm/kfence.h>. */
+#ifndef arch_kfence_test_address
+#define arch_kfence_test_address(addr) (addr)
+#endif
+
 /* Report as observed from console. */
 static struct {
        spinlock_t lock;

@@ -82,6 +89,7 @@ static const char *get_access_type(const struct expect_report *r)
 /* Check observed report matches information in @r. */
 static bool report_matches(const struct expect_report *r)
 {
+       unsigned long addr = (unsigned long)r->addr;
        bool ret = false;
        unsigned long flags;
        typeof(observed.lines) expect;

@@ -131,22 +139,25 @@ static bool report_matches(const struct expect_report *r)
        switch (r->type) {
        case KFENCE_ERROR_OOB:
                cur += scnprintf(cur, end - cur, "Out-of-bounds %s at", get_access_type(r));
+               addr = arch_kfence_test_address(addr);

Can we normalize addr once before (or after) this switch?

I don't think so. When reporing corrupted memory or an invalid free the
address is not generated by hardware but kfence itself, and therefore we
would strip valid bits.

Ah, sorry, I missed that.