[PATCH v3 0/2] powerpc: Emulation support for load/store instructions on LE

[PATCH v3 0/2] powerpc: Emulation support for load/store instructions on LE

[Ravi Bangoria]

emulate_step is the basic infrastructure which is used by number of other
kernel infrastructures like kprobe, hw-breakpoint(data breakpoint) etc.
In case of kprobe, enabling emulation of load/store instructions will
speedup the execution of probed instruction. In case of kernel-space
breakpoint, causative instruction is first get emulated before executing
user registered handler. If emulation fails, hw-breakpoint is disabled
with error. As emulate_step does not support load/store instructions on
LE, kernel-space hw-breakpoint infrastructure is broken on LE.

emulate_step() uses a number of underlying kernel functions that were
initially not enabled for LE. This has been rectified since. So, fix
emulate_step() for LE for the corresponding instructions.

Also add selftest which will run at boot if CONFIG_KPROBES_SANITY_TEST
and CONFIG_PPC64 is set.

Changes in v3:
  - Rebased to powerpc/next. No functionality changes.

v2 link: https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg1332638.html

Ravi Bangoria (2):
  powerpc: Emulation support for load/store instructions on LE
  powerpc: emulate_step tests for load/store instructions

 arch/powerpc/include/asm/ppc-opcode.h |   7 +
 arch/powerpc/include/asm/sstep.h      |   8 +
 arch/powerpc/kernel/kprobes.c         |   2 +
 arch/powerpc/lib/Makefile             |   4 +
 arch/powerpc/lib/sstep.c              |  20 --
 arch/powerpc/lib/test_emulate_step.c  | 439 ++++++++++++++++++++++++++++++++++
 6 files changed, 460 insertions(+), 20 deletions(-)
 create mode 100644 arch/powerpc/lib/test_emulate_step.c

-- 
1.8.3.1

[PATCH v3 1/2] powerpc: Emulation support for load/store instructions on LE

[Ravi Bangoria]

emulate_step() uses a number of underlying kernel functions that were
initially not enabled for LE. This has been rectified since. So, fix
emulate_step() for LE for the corresponding instructions.

Reported-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com>
---
 arch/powerpc/lib/sstep.c | 20 --------------------
 1 file changed, 20 deletions(-)

diff --git a/arch/powerpc/lib/sstep.c b/arch/powerpc/lib/sstep.c
index 846dba2..9c542ec 100644
--- a/arch/powerpc/lib/sstep.c
+++ b/arch/powerpc/lib/sstep.c
@@ -1799,8 +1799,6 @@ int __kprobes emulate_step(struct pt_regs *regs, unsigned int instr)
 		goto instr_done;
 
 	case LARX:
-		if (regs->msr & MSR_LE)
-			return 0;
 		if (op.ea & (size - 1))
 			break;		/* can't handle misaligned */
 		if (!address_ok(regs, op.ea, size))
@@ -1823,8 +1821,6 @@ int __kprobes emulate_step(struct pt_regs *regs, unsigned int instr)
 		goto ldst_done;
 
 	case STCX:
-		if (regs->msr & MSR_LE)
-			return 0;
 		if (op.ea & (size - 1))
 			break;		/* can't handle misaligned */
 		if (!address_ok(regs, op.ea, size))
@@ -1849,8 +1845,6 @@ int __kprobes emulate_step(struct pt_regs *regs, unsigned int instr)
 		goto ldst_done;
 
 	case LOAD:
-		if (regs->msr & MSR_LE)
-			return 0;
 		err = read_mem(&regs->gpr[op.reg], op.ea, size, regs);
 		if (!err) {
 			if (op.type & SIGNEXT)
@@ -1862,8 +1856,6 @@ int __kprobes emulate_step(struct pt_regs *regs, unsigned int instr)
 
 #ifdef CONFIG_PPC_FPU
 	case LOAD_FP:
-		if (regs->msr & MSR_LE)
-			return 0;
 		if (size == 4)
 			err = do_fp_load(op.reg, do_lfs, op.ea, size, regs);
 		else
@@ -1872,15 +1864,11 @@ int __kprobes emulate_step(struct pt_regs *regs, unsigned int instr)
 #endif
 #ifdef CONFIG_ALTIVEC
 	case LOAD_VMX:
-		if (regs->msr & MSR_LE)
-			return 0;
 		err = do_vec_load(op.reg, do_lvx, op.ea & ~0xfUL, regs);
 		goto ldst_done;
 #endif
 #ifdef CONFIG_VSX
 	case LOAD_VSX:
-		if (regs->msr & MSR_LE)
-			return 0;
 		err = do_vsx_load(op.reg, do_lxvd2x, op.ea, regs);
 		goto ldst_done;
 #endif
@@ -1903,8 +1891,6 @@ int __kprobes emulate_step(struct pt_regs *regs, unsigned int instr)
 		goto instr_done;
 
 	case STORE:
-		if (regs->msr & MSR_LE)
-			return 0;
 		if ((op.type & UPDATE) && size == sizeof(long) &&
 		    op.reg == 1 && op.update_reg == 1 &&
 		    !(regs->msr & MSR_PR) &&
@@ -1917,8 +1903,6 @@ int __kprobes emulate_step(struct pt_regs *regs, unsigned int instr)
 
 #ifdef CONFIG_PPC_FPU
 	case STORE_FP:
-		if (regs->msr & MSR_LE)
-			return 0;
 		if (size == 4)
 			err = do_fp_store(op.reg, do_stfs, op.ea, size, regs);
 		else
@@ -1927,15 +1911,11 @@ int __kprobes emulate_step(struct pt_regs *regs, unsigned int instr)
 #endif
 #ifdef CONFIG_ALTIVEC
 	case STORE_VMX:
-		if (regs->msr & MSR_LE)
-			return 0;
 		err = do_vec_store(op.reg, do_stvx, op.ea & ~0xfUL, regs);
 		goto ldst_done;
 #endif
 #ifdef CONFIG_VSX
 	case STORE_VSX:
-		if (regs->msr & MSR_LE)
-			return 0;
 		err = do_vsx_store(op.reg, do_stxvd2x, op.ea, regs);
 		goto ldst_done;
 #endif
-- 
1.8.3.1

[PATCH v3 2/2] powerpc: emulate_step tests for load/store instructions

[Ravi Bangoria]

Add new selftest that test emulate_step for Normal, Floating Point,
Vector and Vector Scalar - load/store instructions. Test should run
at boot time if CONFIG_KPROBES_SANITY_TEST and CONFIG_PPC64 is set.

Sample log:

  [    0.762063] emulate_step smoke test: start.
  [    0.762219] emulate_step smoke test: ld             : PASS
  [    0.762434] emulate_step smoke test: lwz            : PASS
  [    0.762653] emulate_step smoke test: lwzx           : PASS
  [    0.762867] emulate_step smoke test: std            : PASS
  [    0.763082] emulate_step smoke test: ldarx / stdcx. : PASS
  [    0.763302] emulate_step smoke test: lfsx           : PASS
  [    0.763514] emulate_step smoke test: stfsx          : PASS
  [    0.763727] emulate_step smoke test: lfdx           : PASS
  [    0.763942] emulate_step smoke test: stfdx          : PASS
  [    0.764134] emulate_step smoke test: lvx            : PASS
  [    0.764349] emulate_step smoke test: stvx           : PASS
  [    0.764575] emulate_step smoke test: lxvd2x         : PASS
  [    0.764788] emulate_step smoke test: stxvd2x        : PASS
  [    0.764997] emulate_step smoke test: complete.

Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com>
---
 arch/powerpc/include/asm/ppc-opcode.h |   7 +
 arch/powerpc/include/asm/sstep.h      |   8 +
 arch/powerpc/kernel/kprobes.c         |   2 +
 arch/powerpc/lib/Makefile             |   4 +
 arch/powerpc/lib/test_emulate_step.c  | 439 ++++++++++++++++++++++++++++++++++
 5 files changed, 460 insertions(+)
 create mode 100644 arch/powerpc/lib/test_emulate_step.c

diff --git a/arch/powerpc/include/asm/ppc-opcode.h b/arch/powerpc/include/asm/ppc-opcode.h
index d99bd44..e7d6d86 100644
--- a/arch/powerpc/include/asm/ppc-opcode.h
+++ b/arch/powerpc/include/asm/ppc-opcode.h
@@ -284,6 +284,13 @@
 #define PPC_INST_BRANCH_COND		0x40800000
 #define PPC_INST_LBZCIX			0x7c0006aa
 #define PPC_INST_STBCIX			0x7c0007aa
+#define PPC_INST_LWZX			0x7c00002e
+#define PPC_INST_LFSX			0x7c00042e
+#define PPC_INST_STFSX			0x7c00052e
+#define PPC_INST_LFDX			0x7c0004ae
+#define PPC_INST_STFDX			0x7c0005ae
+#define PPC_INST_LVX			0x7c0000ce
+#define PPC_INST_STVX			0x7c0001ce
 
 /* macros to insert fields into opcodes */
 #define ___PPC_RA(a)	(((a) & 0x1f) << 16)
diff --git a/arch/powerpc/include/asm/sstep.h b/arch/powerpc/include/asm/sstep.h
index d3a42cc..d6d3630 100644
--- a/arch/powerpc/include/asm/sstep.h
+++ b/arch/powerpc/include/asm/sstep.h
@@ -87,3 +87,11 @@ struct instruction_op {
 
 extern int analyse_instr(struct instruction_op *op, struct pt_regs *regs,
 			 unsigned int instr);
+
+#if defined(CONFIG_KPROBES_SANITY_TEST) && defined(CONFIG_PPC64)
+void test_emulate_step(void);
+#else
+static inline void test_emulate_step(void)
+{
+}
+#endif
diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c
index fce05a3..5c5ae66 100644
--- a/arch/powerpc/kernel/kprobes.c
+++ b/arch/powerpc/kernel/kprobes.c
@@ -528,6 +528,8 @@ int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
 
 int __init arch_init_kprobes(void)
 {
+	test_emulate_step();
+
 	return register_kprobe(&trampoline_p);
 }
 
diff --git a/arch/powerpc/lib/Makefile b/arch/powerpc/lib/Makefile
index 0e649d7..ddc879d 100644
--- a/arch/powerpc/lib/Makefile
+++ b/arch/powerpc/lib/Makefile
@@ -33,3 +33,7 @@ obj-$(CONFIG_ALTIVEC)	+= xor_vmx.o
 CFLAGS_xor_vmx.o += -maltivec $(call cc-option,-mabi=altivec)
 
 obj-$(CONFIG_PPC64) += $(obj64-y)
+
+ifeq ($(CONFIG_PPC64), y)
+obj-$(CONFIG_KPROBES_SANITY_TEST) += test_emulate_step.o
+endif
diff --git a/arch/powerpc/lib/test_emulate_step.c b/arch/powerpc/lib/test_emulate_step.c
new file mode 100644
index 0000000..887d1db
--- /dev/null
+++ b/arch/powerpc/lib/test_emulate_step.c
@@ -0,0 +1,439 @@
+/*
+ * test_emulate_step.c - simple sanity test for emulate_step load/store
+ *			 instructions
+ *
+ * Copyright IBM Corp. 2016
+ *
+ * This program is free software;  you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it would be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
+ * the GNU General Public License for more details.
+ */
+
+#define pr_fmt(fmt) "emulate_step smoke test: " fmt
+
+#include <linux/ptrace.h>
+#include <asm/sstep.h>
+#include <asm/ppc-opcode.h>
+
+#define IMM_L(i)		((uintptr_t)(i) & 0xffff)
+
+/*
+ * Defined with TEST_ prefix so it does not conflict with other
+ * definitions.
+ */
+#define TEST_LD(r, base, i)	(PPC_INST_LD | ___PPC_RT(r) |		\
+					___PPC_RA(base) | IMM_L(i))
+#define TEST_LWZ(r, base, i)	(PPC_INST_LWZ | ___PPC_RT(r) |		\
+					___PPC_RA(base) | IMM_L(i))
+#define TEST_LWZX(t, a, b)	(PPC_INST_LWZX | ___PPC_RT(t) |		\
+					___PPC_RA(a) | ___PPC_RB(b))
+#define TEST_STD(r, base, i)	(PPC_INST_STD | ___PPC_RS(r) |		\
+					___PPC_RA(base) | ((i) & 0xfffc))
+#define TEST_LDARX(t, a, b, eh)	(PPC_INST_LDARX | ___PPC_RT(t) |	\
+					___PPC_RA(a) | ___PPC_RB(b) |	\
+					__PPC_EH(eh))
+#define TEST_STDCX(s, a, b)	(PPC_INST_STDCX | ___PPC_RS(s) |	\
+					___PPC_RA(a) | ___PPC_RB(b))
+#define TEST_LFSX(t, a, b)	(PPC_INST_LFSX | ___PPC_RT(t) |		\
+					___PPC_RA(a) | ___PPC_RB(b))
+#define TEST_STFSX(s, a, b)	(PPC_INST_STFSX | ___PPC_RS(s) |	\
+					___PPC_RA(a) | ___PPC_RB(b))
+#define TEST_LFDX(t, a, b)	(PPC_INST_LFDX | ___PPC_RT(t) |		\
+					___PPC_RA(a) | ___PPC_RB(b))
+#define TEST_STFDX(s, a, b)	(PPC_INST_STFDX | ___PPC_RS(s) |	\
+					___PPC_RA(a) | ___PPC_RB(b))
+#define TEST_LVX(t, a, b)	(PPC_INST_LVX | ___PPC_RT(t) |		\
+					___PPC_RA(a) | ___PPC_RB(b))
+#define TEST_STVX(s, a, b)	(PPC_INST_STVX | ___PPC_RS(s) |		\
+					___PPC_RA(a) | ___PPC_RB(b))
+#define TEST_LXVD2X(s, a, b)	(PPC_INST_LXVD2X | VSX_XX1((s), R##a, R##b))
+#define TEST_STXVD2X(s, a, b)	(PPC_INST_STXVD2X | VSX_XX1((s), R##a, R##b))
+
+
+static void init_pt_regs(struct pt_regs *regs)
+{
+	static unsigned long msr;
+	static bool msr_cached;
+
+	memset(regs, 0, sizeof(struct pt_regs));
+
+	if (likely(msr_cached)) {
+		regs->msr = msr;
+		return;
+	}
+
+	asm volatile("mfmsr %0" : "=r"(regs->msr));
+
+	regs->msr |= MSR_FP;
+	regs->msr |= MSR_VEC;
+	regs->msr |= MSR_VSX;
+
+	msr = regs->msr;
+	msr_cached = true;
+}
+
+static void show_result(char *ins, char *result)
+{
+	pr_info("%-14s : %s\n", ins, result);
+}
+
+static void test_ld(void)
+{
+	struct pt_regs regs;
+	unsigned long a = 0x23;
+	int stepped = -1;
+
+	init_pt_regs(&regs);
+	regs.gpr[3] = (unsigned long) &a;
+
+	/* ld r5, 0(r3) */
+	stepped = emulate_step(&regs, TEST_LD(5, 3, 0));
+
+	if (stepped == 1 && regs.gpr[5] == a)
+		show_result("ld", "PASS");
+	else
+		show_result("ld", "FAIL");
+}
+
+static void test_lwz(void)
+{
+	struct pt_regs regs;
+	unsigned int a = 0x4545;
+	int stepped = -1;
+
+	init_pt_regs(&regs);
+	regs.gpr[3] = (unsigned long) &a;
+
+	/* lwz r5, 0(r3) */
+	stepped = emulate_step(&regs, TEST_LWZ(5, 3, 0));
+
+	if (stepped == 1 && regs.gpr[5] == a)
+		show_result("lwz", "PASS");
+	else
+		show_result("lwz", "FAIL");
+}
+
+static void test_lwzx(void)
+{
+	struct pt_regs regs;
+	unsigned int a[3] = {0x0, 0x0, 0x1234};
+	int stepped = -1;
+
+	init_pt_regs(&regs);
+	regs.gpr[3] = (unsigned long) a;
+	regs.gpr[4] = 8;
+	regs.gpr[5] = 0x8765;
+
+	/* lwzx r5, r3, r4 */
+	stepped = emulate_step(&regs, TEST_LWZX(5, 3, 4));
+	if (stepped == 1 && regs.gpr[5] == a[2])
+		show_result("lwzx", "PASS");
+	else
+		show_result("lwzx", "FAIL");
+}
+
+static void test_std(void)
+{
+	struct pt_regs regs;
+	unsigned long a = 0x1234;
+	int stepped = -1;
+
+	init_pt_regs(&regs);
+	regs.gpr[3] = (unsigned long) &a;
+	regs.gpr[5] = 0x5678;
+
+	/* std r5, 0(r3) */
+	stepped = emulate_step(&regs, TEST_STD(5, 3, 0));
+	if (stepped == 1 || regs.gpr[5] == a)
+		show_result("std", "PASS");
+	else
+		show_result("std", "FAIL");
+}
+
+static void test_ldarx_stdcx(void)
+{
+	struct pt_regs regs;
+	unsigned long a = 0x1234;
+	int stepped = -1;
+	unsigned long cr0_eq = 0x1 << 29; /* eq bit of CR0 */
+
+	init_pt_regs(&regs);
+	asm volatile("mfcr %0" : "=r"(regs.ccr));
+
+
+	/*** ldarx ***/
+
+	regs.gpr[3] = (unsigned long) &a;
+	regs.gpr[4] = 0;
+	regs.gpr[5] = 0x5678;
+
+	/* ldarx r5, r3, r4, 0 */
+	stepped = emulate_step(&regs, TEST_LDARX(5, 3, 4, 0));
+
+	/*
+	 * Don't touch 'a' here. Touching 'a' can do Load/store
+	 * of 'a' which result in failure of subsequent stdcx.
+	 * Instead, use hardcoded value for comparison.
+	 */
+	if (stepped <= 0 || regs.gpr[5] != 0x1234) {
+		show_result("ldarx / stdcx.", "FAIL (ldarx)");
+		return;
+	}
+
+
+	/*** stdcx. ***/
+
+	regs.gpr[5] = 0x9ABC;
+
+	/* stdcx. r5, r3, r4 */
+	stepped = emulate_step(&regs, TEST_STDCX(5, 3, 4));
+
+	/*
+	 * Two possible scenarios that indicates successful emulation
+	 * of stdcx. :
+	 *  1. Reservation is active and store is performed. In this
+	 *     case cr0.eq bit will be set to 1.
+	 *  2. Reservation is not active and store is not performed.
+	 *     In this case cr0.eq bit will be set to 0.
+	 */
+	if (stepped == 1 && ((regs.gpr[5] == a && (regs.ccr & cr0_eq))
+			|| (regs.gpr[5] != a && !(regs.ccr & cr0_eq))))
+		show_result("ldarx / stdcx.", "PASS");
+	else
+		show_result("ldarx / stdcx.", "FAIL (stdcx.)");
+}
+
+#ifdef CONFIG_PPC_FPU
+static void test_lfsx_stfsx(void)
+{
+	struct pt_regs regs;
+	union {
+		float a;
+		int b;
+	} c;
+	int cached_b;
+	int stepped = -1;
+
+	init_pt_regs(&regs);
+
+
+	/*** lfsx ***/
+
+	c.a = 123.45;
+	cached_b = c.b;
+
+	regs.gpr[3] = (unsigned long) &c.a;
+	regs.gpr[4] = 0;
+
+	/* lfsx frt10, r3, r4 */
+	stepped = emulate_step(&regs, TEST_LFSX(10, 3, 4));
+
+	if (stepped == 1)
+		show_result("lfsx", "PASS");
+	else
+		show_result("lfsx", "FAIL");
+
+
+	/*** stfsx ***/
+
+	c.a = 678.91;
+
+	/* stfsx frs10, r3, r4 */
+	stepped = emulate_step(&regs, TEST_STFSX(10, 3, 4));
+
+	if (stepped == 1 && c.b == cached_b)
+		show_result("stfsx", "PASS");
+	else
+		show_result("stfsx", "FAIL");
+}
+
+static void test_lfdx_stfdx(void)
+{
+	struct pt_regs regs;
+	union {
+		double a;
+		long b;
+	} c;
+	long cached_b;
+	int stepped = -1;
+
+	init_pt_regs(&regs);
+
+
+	/*** lfdx ***/
+
+	c.a = 123456.78;
+	cached_b = c.b;
+
+	regs.gpr[3] = (unsigned long) &c.a;
+	regs.gpr[4] = 0;
+
+	/* lfdx frt10, r3, r4 */
+	stepped = emulate_step(&regs, TEST_LFDX(10, 3, 4));
+
+	if (stepped == 1)
+		show_result("lfdx", "PASS");
+	else
+		show_result("lfdx", "FAIL");
+
+
+	/*** stfdx ***/
+
+	c.a = 987654.32;
+
+	/* stfdx frs10, r3, r4 */
+	stepped = emulate_step(&regs, TEST_STFDX(10, 3, 4));
+
+	if (stepped == 1 && c.b == cached_b)
+		show_result("stfdx", "PASS");
+	else
+		show_result("stfdx", "FAIL");
+}
+#else
+static void test_lfsx_stfsx(void)
+{
+	show_result("lfsx", "SKIP (CONFIG_PPC_FPU is not set)");
+	show_result("stfsx", "SKIP (CONFIG_PPC_FPU is not set)");
+}
+
+static void test_lfdx_stfdx(void)
+{
+	show_result("lfdx", "SKIP (CONFIG_PPC_FPU is not set)");
+	show_result("stfdx", "SKIP (CONFIG_PPC_FPU is not set)");
+}
+#endif /* CONFIG_PPC_FPU */
+
+#ifdef CONFIG_ALTIVEC
+static void test_lvx_stvx(void)
+{
+	struct pt_regs regs;
+	union {
+		vector128 a;
+		u32 b[4];
+	} c;
+	u32 cached_b[4];
+	int stepped = -1;
+
+	init_pt_regs(&regs);
+
+
+	/*** lvx ***/
+
+	cached_b[0] = c.b[0] = 923745;
+	cached_b[1] = c.b[1] = 2139478;
+	cached_b[2] = c.b[2] = 9012;
+	cached_b[3] = c.b[3] = 982134;
+
+	regs.gpr[3] = (unsigned long) &c.a;
+	regs.gpr[4] = 0;
+
+	/* lvx vrt10, r3, r4 */
+	stepped = emulate_step(&regs, TEST_LVX(10, 3, 4));
+
+	if (stepped == 1)
+		show_result("lvx", "PASS");
+	else
+		show_result("lvx", "FAIL");
+
+
+	/*** stvx ***/
+
+	c.b[0] = 4987513;
+	c.b[1] = 84313948;
+	c.b[2] = 71;
+	c.b[3] = 498532;
+
+	/* stvx vrs10, r3, r4 */
+	stepped = emulate_step(&regs, TEST_STVX(10, 3, 4));
+
+	if (stepped == 1 && cached_b[0] == c.b[0] && cached_b[1] == c.b[1] &&
+	    cached_b[2] == c.b[2] && cached_b[3] == c.b[3])
+		show_result("stvx", "PASS");
+	else
+		show_result("stvx", "FAIL");
+}
+#else
+static void test_lvx_stvx(void)
+{
+	show_result("lvx", "SKIP (CONFIG_ALTIVEC is not set)");
+	show_result("stvx", "SKIP (CONFIG_ALTIVEC is not set)");
+}
+#endif /* CONFIG_ALTIVEC */
+
+#ifdef CONFIG_VSX
+static void test_lxvd2x_stxvd2x(void)
+{
+	struct pt_regs regs;
+	union {
+		vector128 a;
+		u32 b[4];
+	} c;
+	u32 cached_b[4];
+	int stepped = -1;
+
+	init_pt_regs(&regs);
+
+
+	/*** lxvd2x ***/
+
+	cached_b[0] = c.b[0] = 18233;
+	cached_b[1] = c.b[1] = 34863571;
+	cached_b[2] = c.b[2] = 834;
+	cached_b[3] = c.b[3] = 6138911;
+
+	regs.gpr[3] = (unsigned long) &c.a;
+	regs.gpr[4] = 0;
+
+	/* lxvd2x vsr39, r3, r4 */
+	stepped = emulate_step(&regs, TEST_LXVD2X(39, 3, 4));
+
+	if (stepped == 1)
+		show_result("lxvd2x", "PASS");
+	else
+		show_result("lxvd2x", "FAIL");
+
+
+	/*** stxvd2x ***/
+
+	c.b[0] = 21379463;
+	c.b[1] = 87;
+	c.b[2] = 374234;
+	c.b[3] = 4;
+
+	/* stxvd2x vsr39, r3, r4 */
+	stepped = emulate_step(&regs, TEST_STXVD2X(39, 3, 4));
+
+	if (stepped == 1 && cached_b[0] == c.b[0] && cached_b[1] == c.b[1] &&
+	    cached_b[2] == c.b[2] && cached_b[3] == c.b[3])
+		show_result("stxvd2x", "PASS");
+	else
+		show_result("stxvd2x", "FAIL");
+}
+#else
+static void test_lxvd2x_stxvd2x(void)
+{
+	show_result("lxvd2x", "SKIP (CONFIG_VSX is not set)");
+	show_result("stxvd2x", "SKIP (CONFIG_VSX is not set)");
+}
+#endif /* CONFIG_VSX */
+
+void test_emulate_step(void)
+{
+	pr_info("start.\n");
+	test_ld();
+	test_lwz();
+	test_lwzx();
+	test_std();
+	test_ldarx_stdcx();
+	test_lfsx_stfsx();
+	test_lfdx_stfdx();
+	test_lvx_stvx();
+	test_lxvd2x_stxvd2x();
+	pr_info("complete.\n");
+}
-- 
1.8.3.1

Re: [PATCH v3 1/2] powerpc: Emulation support for load/store instructions on LE

[Michael Ellerman]

Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com> writes:

> emulate_step() uses a number of underlying kernel functions that were
> initially not enabled for LE. This has been rectified since.

When exactly? ie. which commit.

Should we backport this? ie. is it actually a bug people are hitting in
the real world much?

cheers

Re: [PATCH v3 2/2] powerpc: emulate_step tests for load/store instructions

[Michael Ellerman]

Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com> writes:

> diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c
> index fce05a3..5c5ae66 100644
> --- a/arch/powerpc/kernel/kprobes.c
> +++ b/arch/powerpc/kernel/kprobes.c
> @@ -528,6 +528,8 @@ int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
>  
>  int __init arch_init_kprobes(void)
>  {
> +	test_emulate_step();
> +

I don't see any good reason why this is called from here.

So I'm inclined to just make test_emulate_step() a regular init call.

cheers

Re: [PATCH v3 2/2] powerpc: emulate_step tests for load/store instructions

[Michael Ellerman]

Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com> writes:

> diff --git a/arch/powerpc/lib/Makefile b/arch/powerpc/lib/Makefile
> index 0e649d7..ddc879d 100644
> --- a/arch/powerpc/lib/Makefile
> +++ b/arch/powerpc/lib/Makefile
> @@ -33,3 +33,7 @@ obj-$(CONFIG_ALTIVEC)	+= xor_vmx.o
>  CFLAGS_xor_vmx.o += -maltivec $(call cc-option,-mabi=altivec)
>  
>  obj-$(CONFIG_PPC64) += $(obj64-y)
> +
> +ifeq ($(CONFIG_PPC64), y)
> +obj-$(CONFIG_KPROBES_SANITY_TEST) += test_emulate_step.o
> +endif

FYI, the right way to do that is:

  obj64-$(CONFIG_KPROBES_SANITY_TEST) += test_emulate_step.o
  obj-$(CONFIG_PPC64) += $(obj64-y)

And in this Makefile you don't need to add the second line because it's
already there.

cheers

Re: [PATCH v3 1/2] powerpc: Emulation support for load/store instructions on LE

[Ravi Bangoria]

Thanks Michael,

On Tuesday 14 February 2017 03:50 PM, Michael Ellerman wrote:
> Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com> writes:
>
>> emulate_step() uses a number of underlying kernel functions that were
>> initially not enabled for LE. This has been rectified since.
> When exactly? ie. which commit.

I found couple of commits:

6506b4718b ("powerpc: Fix Unaligned Loads and Stores")
dbc2fbd7c2 ("powerpc: Fix Unaligned LE Floating Point Loads and Stores")

There may be more.

Patch2 is to test emulate_step() for basic load/store instructions and it
seems to be working fine on LE.

>
> Should we backport this? ie. is it actually a bug people are hitting in
> the real world much?

Yes, we should backport this. kernel-space hw-breakpoint feature is broken
on LE without this. This is on ppc64le:

  $ sudo cat /proc/kallsyms  | grep pid_max
    c00000000116998c D pid_max

  $ sudo ./perf record -a --event=mem:0xc00000000116998c sleep 10


Before patch:
  It does not record any data and throws below warning.

  $ dmesg
    [  817.895573] Unable to handle hardware breakpoint. Breakpoint at 0xc00000000116998c will be disabled.
    [  817.895581] ------------[ cut here ]------------
    [  817.895588] WARNING: CPU: 24 PID: 2032 at arch/powerpc/kernel/hw_breakpoint.c:277 hw_breakpoint_handler+0x124/0x230
    ...

After patch:
  It records data properly.

  $ sudo ./perf report --stdio
    ...
    # Samples: 36  of event 'mem:0xc00000000116998c'
    # Event count (approx.): 36
    #
    # Overhead  Command        Shared Object     Symbol     
    # ........  .............  ................  .............
    #
        63.89%  kdumpctl       [kernel.vmlinux]  [k] alloc_pid
        27.78%  opal_errd      [kernel.vmlinux]  [k] alloc_pid
         5.56%  kworker/u97:4  [kernel.vmlinux]  [k] alloc_pid
         2.78%  systemd        [kernel.vmlinux]  [k] alloc_pid



>
> cheers
>

Re: [PATCH v3 2/2] powerpc: emulate_step tests for load/store instructions

[Ravi Bangoria]

On Tuesday 14 February 2017 04:16 PM, Michael Ellerman wrote:
> Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com> writes:
>
>> diff --git a/arch/powerpc/lib/Makefile b/arch/powerpc/lib/Makefile
>> index 0e649d7..ddc879d 100644
>> --- a/arch/powerpc/lib/Makefile
>> +++ b/arch/powerpc/lib/Makefile
>> @@ -33,3 +33,7 @@ obj-$(CONFIG_ALTIVEC)	+= xor_vmx.o
>>  CFLAGS_xor_vmx.o += -maltivec $(call cc-option,-mabi=altivec)
>>  
>>  obj-$(CONFIG_PPC64) += $(obj64-y)
>> +
>> +ifeq ($(CONFIG_PPC64), y)
>> +obj-$(CONFIG_KPROBES_SANITY_TEST) += test_emulate_step.o
>> +endif
> FYI, the right way to do that is:
>
>   obj64-$(CONFIG_KPROBES_SANITY_TEST) += test_emulate_step.o
>   obj-$(CONFIG_PPC64) += $(obj64-y)
>
> And in this Makefile you don't need to add the second line because it's
> already there.

Thanks for this. Will change accordingly and send next version.

Ravi

>
> cheers
>

Re: [v3, 1/2] powerpc: Emulation support for load/store instructions on LE

[Michael Ellerman]

On Tue, 2017-02-14 at 09:16:42 UTC, Ravi Bangoria wrote:
> emulate_step() uses a number of underlying kernel functions that were
> initially not enabled for LE. This has been rectified since. So, fix
> emulate_step() for LE for the corresponding instructions.
> 
> Reported-by: Anton Blanchard <anton@samba.org>
> Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com>

Series applied to powerpc fixes, thanks.

https://git.kernel.org/powerpc/c/e148bd17f48bd17fca2f4f089ec879

cheers