[PATCH 1/3] powerpc: asm/ppc-opcode.h: introduce __PPC_SH64()

@@ -306,6 +306,7 @@
 #define __PPC_WC(w)	(((w) & 0x3) << 21)
 #define __PPC_WS(w)	(((w) & 0x1f) << 11)
 #define __PPC_SH(s)	__PPC_WS(s)
+#define __PPC_SH64(s)	(__PPC_SH(s) | (((s) & 0x20) >> 4))
 #define __PPC_MB(s)	(((s) & 0x1f) << 6)
 #define __PPC_ME(s)	(((s) & 0x1f) << 1)
 #define __PPC_MB64(s)	(__PPC_MB(s) | ((s) & 0x20))

@@ -157,8 +157,7 @@
 #define PPC_SRAD(d, a, s)	EMIT(PPC_INST_SRAD | ___PPC_RA(d) |	      \
 				     ___PPC_RS(a) | ___PPC_RB(s))
 #define PPC_SRADI(d, a, i)	EMIT(PPC_INST_SRADI | ___PPC_RA(d) |	      \
-				     ___PPC_RS(a) | __PPC_SH(i) |             \
-				     (((i) & 0x20) >> 4))
+				     ___PPC_RS(a) | __PPC_SH64(i))
 #define PPC_RLWINM(d, a, i, mb, me)	EMIT(PPC_INST_RLWINM | ___PPC_RA(d) | \
 					___PPC_RS(a) | __PPC_SH(i) |	      \
 					__PPC_MB(mb) | __PPC_ME(me))

@@ -166,11 +165,11 @@
 					___PPC_RS(a) | __PPC_SH(i) |	      \
 					__PPC_MB(mb) | __PPC_ME(me))
 #define PPC_RLDICL(d, a, i, mb)		EMIT(PPC_INST_RLDICL | ___PPC_RA(d) | \
-					___PPC_RS(a) | __PPC_SH(i) |	      \
-					__PPC_MB64(mb) | (((i) & 0x20) >> 4))
+					___PPC_RS(a) | __PPC_SH64(i) |	      \
+					__PPC_MB64(mb))
 #define PPC_RLDICR(d, a, i, me)		EMIT(PPC_INST_RLDICR | ___PPC_RA(d) | \
-					___PPC_RS(a) | __PPC_SH(i) |	      \
-					__PPC_ME64(me) | (((i) & 0x20) >> 4))
+					___PPC_RS(a) | __PPC_SH64(i) |	      \
+					__PPC_ME64(me))
 
 /* slwi = rlwinm Rx, Ry, n, 0, 31-n */
 #define PPC_SLWI(d, a, i)	PPC_RLWINM(d, a, i, 0, 31-(i))

@@ -29,6 +29,7 @@
 #include <linux/types.h>
 #include <linux/ptrace.h>
 #include <linux/percpu.h>
+#include <linux/module.h>
 #include <asm/probes.h>
 #include <asm/code-patching.h>
 

@@ -61,7 +62,7 @@ typedef ppc_opcode_t kprobe_opcode_t;
 #define kprobe_lookup_name(name, addr)					\
 {									\
 	char dot_name[MODULE_NAME_LEN + 1 + KSYM_NAME_LEN];		\
-	char *modsym;							\
+	const char *modsym;							\
 	bool dot_appended = false;					\
 	if ((modsym = strchr(name, ':')) != NULL) {			\
 		modsym++;						\

@@ -22,6 +22,7 @@
 #define BRANCH_SET_LINK	0x1
 #define BRANCH_ABSOLUTE	0x2
 
+bool is_offset_in_branch_range(long offset);
 unsigned int create_branch(const unsigned int *addr,
 			   unsigned long target, int flags);
 unsigned int create_cond_branch(const unsigned int *addr,

@@ -32,6 +32,28 @@ int patch_branch(unsigned int *addr, unsigned long target, int flags)
 	return patch_instruction(addr, create_branch(addr, target, flags));
 }
 
+bool is_offset_in_branch_range(long offset)
+{
+	/*
+	 * Powerpc branch instruction is :
+	 *
+	 *  0         6                 30   31
+	 *  +---------+----------------+---+---+
+	 *  | opcode  |     LI         |AA |LK |
+	 *  +---------+----------------+---+---+
+	 *  Where AA = 0 and LK = 0
+	 *
+	 * LI is a signed 24 bits integer. The real branch offset is computed
+	 * by: imm32 = SignExtend(LI:'0b00', 32);
+	 *
+	 * So the maximum forward branch should be:
+	 *   (0x007fffff << 2) = 0x01fffffc =  0x1fffffc
+	 * The maximum backward branch should be:
+	 *   (0xff800000 << 2) = 0xfe000000 = -0x2000000
+	 */
+	return (offset >= -0x2000000 && offset <= 0x1fffffc && !(offset & 0x3));
+}
+
 unsigned int create_branch(const unsigned int *addr,
 			   unsigned long target, int flags)
 {

@@ -43,7 +65,7 @@ unsigned int create_branch(const unsigned int *addr,
 		offset = offset - (unsigned long)addr;
 
 	/* Check we can represent the target in the instruction format */
-	if (offset < -0x2000000 || offset > 0x1fffffc || offset & 0x3)
+	if (!is_offset_in_branch_range(offset))
 		return 0;
 
 	/* Mask out the flags and target, so they don't step on each other. */