LinuxPPC-Dev Archive on lore.kernel.org
 help / color / Atom feed
From: Ganesh Goudar <ganeshgr@linux.ibm.com>
To: linuxppc-dev@lists.ozlabs.org, mpe@ellerman.id.au
Cc: msuchanek@suse.de, Ganesh Goudar <ganeshgr@linux.ibm.com>,
	keescook@chromium.org, npiggin@gmail.com, mahesh@linux.ibm.com
Subject: [PATCH v4 2/2] lkdtm/powerpc: Add SLB multihit test
Date: Fri,  9 Oct 2020 12:10:05 +0530
Message-ID: <20201009064005.19777-3-ganeshgr@linux.ibm.com> (raw)
In-Reply-To: <20201009064005.19777-1-ganeshgr@linux.ibm.com>

To check machine check handling, add support to inject slb
multihit errors.

Cc: Kees Cook <keescook@chromium.org>
Reviewed-by: Michal Suchánek <msuchanek@suse.de>
Co-developed-by: Mahesh Salgaonkar <mahesh@linux.ibm.com>
Signed-off-by: Mahesh Salgaonkar <mahesh@linux.ibm.com>
Signed-off-by: Ganesh Goudar <ganeshgr@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


  parent reply index

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-09  6:40 [PATCH v4 0/2] powerpc/mce: Fix mce handler and add selftest Ganesh Goudar
2020-10-09  6:40 ` [PATCH v4 1/2] powerpc/mce: remove nmi_enter/exit from real mode handler Ganesh Goudar
2020-10-09  6:40 ` Ganesh Goudar [this message]
2020-10-19 10:59   ` [PATCH v4 2/2] lkdtm/powerpc: Add SLB multihit test Michael Ellerman
2020-10-19 13:15     ` Michal Suchánek
2020-11-26 13:27       ` Ganesh
2020-10-16 11:32 ` [PATCH v4 0/2] powerpc/mce: Fix mce handler and add selftest Michael Ellerman
2020-10-19  5:26   ` Ganesh

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20201009064005.19777-3-ganeshgr@linux.ibm.com \
    --to=ganeshgr@linux.ibm.com \
    --cc=keescook@chromium.org \
    --cc=linuxppc-dev@lists.ozlabs.org \
    --cc=mahesh@linux.ibm.com \
    --cc=mpe@ellerman.id.au \
    --cc=msuchanek@suse.de \
    --cc=npiggin@gmail.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

LinuxPPC-Dev Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linuxppc-dev/0 linuxppc-dev/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linuxppc-dev linuxppc-dev/ https://lore.kernel.org/linuxppc-dev \
		linuxppc-dev@lists.ozlabs.org linuxppc-dev@ozlabs.org
	public-inbox-index linuxppc-dev

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.ozlabs.lists.linuxppc-dev


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git