To check machine check handling, add support to inject slb
multihit errors.
Cc: Kees Cook <keesc...@chromium.org>
Reviewed-by: Michal Suchánek <msucha...@suse.de>
Co-developed-by: Mahesh Salgaonkar <mah...@linux.ibm.com>
Signed-off-by: Mahesh Salgaonkar <mah...@linux.ibm.com>
Signed-off-by: Ganesh Goudar <ganes...@linux.ibm.com>
---
drivers/misc/lkdtm/Makefile | 1 +
drivers/misc/lkdtm/core.c | 3 +
drivers/misc/lkdtm/lkdtm.h | 3 +
drivers/misc/lkdtm/powerpc.c | 156 ++++++++++++++++++++++++
tools/testing/selftests/lkdtm/tests.txt | 1 +
5 files changed, 164 insertions(+)
create mode 100644 drivers/misc/lkdtm/powerpc.c
diff --git a/drivers/misc/lkdtm/Makefile b/drivers/misc/lkdtm/Makefile
index c70b3822013f..f37ecfb0a707 100644
--- a/drivers/misc/lkdtm/Makefile
+++ b/drivers/misc/lkdtm/Makefile
@@ -10,6 +10,7 @@ lkdtm-$(CONFIG_LKDTM) += rodata_objcopy.o
lkdtm-$(CONFIG_LKDTM) += usercopy.o
lkdtm-$(CONFIG_LKDTM) += stackleak.o
lkdtm-$(CONFIG_LKDTM) += cfi.o
+lkdtm-$(CONFIG_PPC64) += powerpc.o
KASAN_SANITIZE_stackleak.o := n
KCOV_INSTRUMENT_rodata.o := n
diff --git a/drivers/misc/lkdtm/core.c b/drivers/misc/lkdtm/core.c
index a5e344df9166..8d5db42baa90 100644
--- a/drivers/misc/lkdtm/core.c
+++ b/drivers/misc/lkdtm/core.c
@@ -178,6 +178,9 @@ static const struct crashtype crashtypes[] = {
#ifdef CONFIG_X86_32
CRASHTYPE(DOUBLE_FAULT),
#endif
+#ifdef CONFIG_PPC64
+ CRASHTYPE(PPC_SLB_MULTIHIT),
+#endif
};
diff --git a/drivers/misc/lkdtm/lkdtm.h b/drivers/misc/lkdtm/lkdtm.h
index 8878538b2c13..b305bd511ee5 100644
--- a/drivers/misc/lkdtm/lkdtm.h
+++ b/drivers/misc/lkdtm/lkdtm.h
@@ -104,4 +104,7 @@ void lkdtm_STACKLEAK_ERASING(void);
/* cfi.c */
void lkdtm_CFI_FORWARD_PROTO(void);
+/* powerpc.c */
+void lkdtm_PPC_SLB_MULTIHIT(void);
+
#endif
diff --git a/drivers/misc/lkdtm/powerpc.c b/drivers/misc/lkdtm/powerpc.c
new file mode 100644
index 000000000000..f388b53dccba
--- /dev/null
+++ b/drivers/misc/lkdtm/powerpc.c
@@ -0,0 +1,156 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include "lkdtm.h"
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+
+/* Gets index for new slb entry */
+static inline unsigned long get_slb_index(void)
+{
+ unsigned long index;
+
+ index = get_paca()->stab_rr;
+
+ /*
+ * simple round-robin replacement of slb starting at SLB_NUM_BOLTED.
+ */
+ if (index < (mmu_slb_size - 1))
+ index++;
+ else
+ index = SLB_NUM_BOLTED;
+ get_paca()->stab_rr = index;
+ return index;
+}
+
+#define slb_esid_mask(ssize) \
+ (((ssize) == MMU_SEGSIZE_256M) ? ESID_MASK : ESID_MASK_1T)
+
+/* Form the operand for slbmte */
+static inline unsigned long mk_esid_data(unsigned long ea, int ssize,
+ unsigned long slot)
+{
+ return (ea & slb_esid_mask(ssize)) | SLB_ESID_V | slot;
+}
+
+#define slb_vsid_shift(ssize) \
+ ((ssize) == MMU_SEGSIZE_256M ? SLB_VSID_SHIFT : SLB_VSID_SHIFT_1T)
+
+/* Form the operand for slbmte */
+static inline unsigned long mk_vsid_data(unsigned long ea, int ssize,
+ unsigned long flags)
+{
+ return (get_kernel_vsid(ea, ssize) << slb_vsid_shift(ssize)) | flags |
+ ((unsigned long)ssize << SLB_VSID_SSIZE_SHIFT);
+}
+
+/* Inserts new slb entry */
+static void insert_slb_entry(char *p, int ssize)
+{
+ unsigned long flags, entry;
+
+ flags = SLB_VSID_KERNEL | mmu_psize_defs[MMU_PAGE_64K].sllp;
+ preempt_disable();
+
+ entry = get_slb_index();
+ asm volatile("slbmte %0,%1" :
+ : "r" (mk_vsid_data((unsigned long)p, ssize, flags)),
+ "r" (mk_esid_data((unsigned long)p, ssize, entry))
+ : "memory");
+
+ entry = get_slb_index();
+ asm volatile("slbmte %0,%1" :
+ : "r" (mk_vsid_data((unsigned long)p, ssize, flags)),
+ "r" (mk_esid_data((unsigned long)p, ssize, entry))
+ : "memory");
+ preempt_enable();
+ /*
+ * This triggers exception, If handled correctly we must recover
+ * from this error.
+ */
+ p[0] = '!';
+}
+
+/* Inject slb multihit on vmalloc-ed address i.e 0xD00... */
+static void inject_vmalloc_slb_multihit(void)
+{
+ char *p;
+
+ p = vmalloc(2048);
+ if (!p)
+ return;
+
+ insert_slb_entry(p, MMU_SEGSIZE_1T);
+ vfree(p);
+}
+
+/* Inject slb multihit on kmalloc-ed address i.e 0xC00... */
+static void inject_kmalloc_slb_multihit(void)
+{
+ char *p;
+
+ p = kmalloc(2048, GFP_KERNEL);
+ if (!p)
+ return;
+
+ insert_slb_entry(p, MMU_SEGSIZE_1T);
+ kfree(p);
+}
+
+/*
+ * Few initial SLB entries are bolted. Add a test to inject
+ * multihit in bolted entry 0.
+ */
+static void insert_dup_slb_entry_0(void)
+{
+ unsigned long test_address = 0xC000000000000000;
+ volatile unsigned long *test_ptr;
+ unsigned long entry, i = 0;
+ unsigned long esid, vsid;
+
+ test_ptr = (unsigned long *)test_address;
+ preempt_disable();
+
+ asm volatile("slbmfee %0,%1" : "=r" (esid) : "r" (i));
+ asm volatile("slbmfev %0,%1" : "=r" (vsid) : "r" (i));
+ entry = get_slb_index();
+
+ /* for i !=0 we would need to mask out the old entry number */
+ asm volatile("slbmte %0,%1" :
+ : "r" (vsid),
+ "r" (esid | entry)
+ : "memory");
+
+ asm volatile("slbmfee %0,%1" : "=r" (esid) : "r" (i));
+ asm volatile("slbmfev %0,%1" : "=r" (vsid) : "r" (i));
+ entry = get_slb_index();
+
+ /* for i !=0 we would need to mask out the old entry number */
+ asm volatile("slbmte %0,%1" :
+ : "r" (vsid),
+ "r" (esid | entry)
+ : "memory");
+
+ pr_info("%s accessing test address 0x%lx: 0x%lx\n",
+ __func__, test_address, *test_ptr);
+
+ preempt_enable();
+}
+
+void lkdtm_PPC_SLB_MULTIHIT(void)
+{
+ if (mmu_has_feature(MMU_FTR_HPTE_TABLE)) {
+ pr_info("Injecting SLB multihit errors\n");
+ /*
+ * These need not be separate tests, And they do pretty
+ * much same thing. In any case we must recover from the
+ * errors introduced by these functions, machine would not
+ * survive these tests in case of failure to handle.
+ */
+ inject_vmalloc_slb_multihit();
+ inject_kmalloc_slb_multihit();
+ insert_dup_slb_entry_0();
+ pr_info("Recovered from SLB multihit errors\n");
+ } else {
+ pr_err("XFAIL: This test is for ppc64 and with hash mode MMU
only\n");
+ }
+}
diff --git a/tools/testing/selftests/lkdtm/tests.txt
b/tools/testing/selftests/lkdtm/tests.txt
index 9d266e79c6a2..7eb3cf91c89e 100644
--- a/tools/testing/selftests/lkdtm/tests.txt
+++ b/tools/testing/selftests/lkdtm/tests.txt
@@ -70,3 +70,4 @@ USERCOPY_KERNEL
USERCOPY_KERNEL_DS
STACKLEAK_ERASING OK: the rest of the thread stack is properly erased
CFI_FORWARD_PROTO
+PPC_SLB_MULTIHIT Recovered
--
2.26.2
