powerpc: Add prefixed instructions to instruction data type

For powerpc64, redefine the ppc_inst type so both word and prefixed
instructions can be represented. On powerpc32 the type will remain the
same. Update places which had assumed instructions to be 4 bytes long.

Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
Reviewed-by: Alistair Popple <alistair@popple.id.au>
[mpe: Rework the get_user_inst() macros to be parameterised, and don't
      assign to the dest if an error occurred. Use CONFIG_PPC64 not
      __powerpc64__ in a few places. Address other comments from
      Christophe. Fix some sparse complaints.]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200506034050.24806-24-jniethe5@gmail.com

5 files changed, 105 insertions, 8 deletions

diff --git a/arch/powerpc/include/asm/inst.h b/arch/powerpc/include/asm/inst.h
index c7ea70e73073..d82e0c99cfa1 100644
--- a/arch/powerpc/include/asm/inst.h
+++ b/arch/powerpc/include/asm/inst.h
@@ -2,29 +2,80 @@
 #ifndef _ASM_POWERPC_INST_H
 #define _ASM_POWERPC_INST_H
 
+#include <asm/ppc-opcode.h>
+
 /*
  * Instruction data type for POWER
  */
 
 struct ppc_inst {
 	u32 val;
+#ifdef CONFIG_PPC64
+	u32 suffix;
+#endif
 } __packed;
 
-#define ppc_inst(x) ((struct ppc_inst){ .val = x })
-
 static inline u32 ppc_inst_val(struct ppc_inst x)
 {
 	return x.val;
 }
 
-static inline int ppc_inst_len(struct ppc_inst x)
+static inline int ppc_inst_primary_opcode(struct ppc_inst x)
 {
-	return sizeof(struct ppc_inst);
+	return ppc_inst_val(x) >> 26;
 }
 
-static inline int ppc_inst_primary_opcode(struct ppc_inst x)
+#ifdef CONFIG_PPC64
+#define ppc_inst(x) ((struct ppc_inst){ .val = (x), .suffix = 0xff })
+
+#define ppc_inst_prefix(x, y) ((struct ppc_inst){ .val = (x), .suffix = (y) })
+
+static inline u32 ppc_inst_suffix(struct ppc_inst x)
 {
-	return ppc_inst_val(x) >> 26;
+	return x.suffix;
+}
+
+static inline bool ppc_inst_prefixed(struct ppc_inst x)
+{
+	return (ppc_inst_primary_opcode(x) == 1) && ppc_inst_suffix(x) != 0xff;
+}
+
+static inline struct ppc_inst ppc_inst_swab(struct ppc_inst x)
+{
+	return ppc_inst_prefix(swab32(ppc_inst_val(x)),
+			       swab32(ppc_inst_suffix(x)));
+}
+
+static inline struct ppc_inst ppc_inst_read(const struct ppc_inst *ptr)
+{
+	u32 val, suffix;
+
+	val = *(u32 *)ptr;
+	if ((val >> 26) == OP_PREFIX) {
+		suffix = *((u32 *)ptr + 1);
+		return ppc_inst_prefix(val, suffix);
+	} else {
+		return ppc_inst(val);
+	}
+}
+
+static inline bool ppc_inst_equal(struct ppc_inst x, struct ppc_inst y)
+{
+	return *(u64 *)&x == *(u64 *)&y;
+}
+
+#else
+
+#define ppc_inst(x) ((struct ppc_inst){ .val = x })
+
+static inline bool ppc_inst_prefixed(struct ppc_inst x)
+{
+	return false;
+}
+
+static inline u32 ppc_inst_suffix(struct ppc_inst x)
+{
+	return 0;
 }
 
 static inline struct ppc_inst ppc_inst_swab(struct ppc_inst x)
@@ -42,6 +93,13 @@ static inline bool ppc_inst_equal(struct ppc_inst x, struct ppc_inst y)
 	return ppc_inst_val(x) == ppc_inst_val(y);
 }
 
+#endif /* CONFIG_PPC64 */
+
+static inline int ppc_inst_len(struct ppc_inst x)
+{
+	return ppc_inst_prefixed(x) ? 8 : 4;
+}
+
 int probe_user_read_inst(struct ppc_inst *inst,
 			 struct ppc_inst __user *nip);
 
diff --git a/arch/powerpc/include/asm/kprobes.h b/arch/powerpc/include/asm/kprobes.h
index 66b3f2983b22..4fc0e15e23a5 100644
--- a/arch/powerpc/include/asm/kprobes.h
+++ b/arch/powerpc/include/asm/kprobes.h
@@ -43,7 +43,7 @@ extern kprobe_opcode_t optprobe_template_ret[];
 extern kprobe_opcode_t optprobe_template_end[];
 
 /* Fixed instruction size for powerpc */
-#define MAX_INSN_SIZE		1
+#define MAX_INSN_SIZE		2
 #define MAX_OPTIMIZED_LENGTH	sizeof(kprobe_opcode_t)	/* 4 bytes */
 #define MAX_OPTINSN_SIZE	(optprobe_template_end - optprobe_template_entry)
 #define RELATIVEJUMP_SIZE	sizeof(kprobe_opcode_t)	/* 4 bytes */
diff --git a/arch/powerpc/include/asm/ppc-opcode.h b/arch/powerpc/include/asm/ppc-opcode.h
index c1df75edde44..2a39c716c343 100644
--- a/arch/powerpc/include/asm/ppc-opcode.h
+++ b/arch/powerpc/include/asm/ppc-opcode.h
@@ -158,6 +158,9 @@
 /* VMX Vector Store Instructions */
 #define OP_31_XOP_STVX          231
 
+/* Prefixed Instructions */
+#define OP_PREFIX		1
+
 #define OP_31   31
 #define OP_LWZ  32
 #define OP_STFS 52
diff --git a/arch/powerpc/include/asm/uaccess.h b/arch/powerpc/include/asm/uaccess.h
index 0d2d0c3dc527..c0523efa1458 100644
--- a/arch/powerpc/include/asm/uaccess.h
+++ b/arch/powerpc/include/asm/uaccess.h
@@ -105,6 +105,40 @@ static inline int __access_ok(unsigned long addr, unsigned long size,
 #define __put_user_inatomic(x, ptr) \
 	__put_user_nosleep((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
 
+#ifdef CONFIG_PPC64
+
+#define ___get_user_instr(gu_op, dest, ptr)				\
+({									\
+	long __gui_ret = 0;						\
+	unsigned long __gui_ptr = (unsigned long)ptr;			\
+	struct ppc_inst __gui_inst;					\
+	unsigned int __prefix, __suffix;				\
+	__gui_ret = gu_op(__prefix, (unsigned int __user *)__gui_ptr);	\
+	if (__gui_ret == 0) {						\
+		if ((__prefix >> 26) == OP_PREFIX) {			\
+			__gui_ret = gu_op(__suffix,			\
+				(unsigned int __user *)__gui_ptr + 1);	\
+			__gui_inst = ppc_inst_prefix(__prefix,		\
+						     __suffix);		\
+		} else {						\
+			__gui_inst = ppc_inst(__prefix);		\
+		}							\
+		if (__gui_ret == 0)					\
+			(dest) = __gui_inst;				\
+	}								\
+	__gui_ret;							\
+})
+
+#define get_user_instr(x, ptr) \
+	___get_user_instr(get_user, x, ptr)
+
+#define __get_user_instr(x, ptr) \
+	___get_user_instr(__get_user, x, ptr)
+
+#define __get_user_instr_inatomic(x, ptr) \
+	___get_user_instr(__get_user_inatomic, x, ptr)
+
+#else /* !CONFIG_PPC64 */
 #define get_user_instr(x, ptr) \
 	get_user((x).val, (u32 __user *)(ptr))
 
@@ -114,6 +148,8 @@ static inline int __access_ok(unsigned long addr, unsigned long size,
 #define __get_user_instr_inatomic(x, ptr) \
 	__get_user_nosleep((x).val, (u32 __user *)(ptr), sizeof(u32))
 
+#endif /* CONFIG_PPC64 */
+
 extern long __put_user_bad(void);
 
 /*
diff --git a/arch/powerpc/include/asm/uprobes.h b/arch/powerpc/include/asm/uprobes.h
index 7e3b329ba2d3..5bf65f5d44a9 100644
--- a/arch/powerpc/include/asm/uprobes.h
+++ b/arch/powerpc/include/asm/uprobes.h
@@ -15,7 +15,7 @@
 
 typedef ppc_opcode_t uprobe_opcode_t;
 
-#define MAX_UINSN_BYTES		4
+#define MAX_UINSN_BYTES		8
 #define UPROBE_XOL_SLOT_BYTES	(MAX_UINSN_BYTES)
 
 /* The following alias is needed for reference from arch-agnostic code */