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Subject[PATCH 1/2] kfence: add function to mask address bits
Date
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>
---
include/linux/kfence.h | 1 +
mm/kfence/core.c | 5 +++++
mm/kfence/kfence_test.c | 6 +++++-
3 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/include/linux/kfence.h b/include/linux/kfence.h
index a70d1ea03532..2e15f4c4ee95 100644
--- a/include/linux/kfence.h
+++ b/include/linux/kfence.h
@@ -199,6 +199,7 @@ static __always_inline __must_check bool kfence_free(void *addr)
* present, so that the kernel can proceed.
*/
bool __must_check kfence_handle_page_fault(unsigned long addr, bool is_write, struct pt_regs *regs);
+unsigned long kfence_arch_mask_addr(unsigned long addr);

#else /* CONFIG_KFENCE */

diff --git a/mm/kfence/core.c b/mm/kfence/core.c
index e18fbbd5d9b4..bc15e3cb71d5 100644
--- a/mm/kfence/core.c
+++ b/mm/kfence/core.c
@@ -50,6 +50,11 @@ static unsigned long kfence_sample_interval __read_mostly = CONFIG_KFENCE_SAMPLE
#endif
#define MODULE_PARAM_PREFIX "kfence."

+unsigned long __weak kfence_arch_mask_addr(unsigned long addr)
+{
+ return addr;
+}
+
static int param_set_sample_interval(const char *val, const struct kernel_param *kp)
{
unsigned long num;
diff --git a/mm/kfence/kfence_test.c b/mm/kfence/kfence_test.c
index 4acf4251ee04..9ec572991014 100644
--- a/mm/kfence/kfence_test.c
+++ b/mm/kfence/kfence_test.c
@@ -82,6 +82,7 @@ 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 +132,25 @@ 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 = kfence_arch_mask_addr(addr);
break;
case KFENCE_ERROR_UAF:
cur += scnprintf(cur, end - cur, "Use-after-free %s at", get_access_type(r));
+ addr = kfence_arch_mask_addr(addr);
break;
case KFENCE_ERROR_CORRUPTION:
cur += scnprintf(cur, end - cur, "Corrupted memory at");
break;
case KFENCE_ERROR_INVALID:
cur += scnprintf(cur, end - cur, "Invalid %s at", get_access_type(r));
+ addr = kfence_arch_mask_addr(addr);
break;
case KFENCE_ERROR_INVALID_FREE:
cur += scnprintf(cur, end - cur, "Invalid free of");
break;
}

- cur += scnprintf(cur, end - cur, " 0x%p", (void *)r->addr);
+ cur += scnprintf(cur, end - cur, " 0x%p", (void *)addr);

spin_lock_irqsave(&observed.lock, flags);
if (!report_available())
--
2.25.1
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