powerpc: Use a function for reading instructions

Prefixed instructions will mean there are instructions of different
length. As a result dereferencing a pointer to an instruction will not
necessarily give the desired result. Introduce a function for reading
instructions from memory into the instruction data type.

Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Alistair Popple <alistair@popple.id.au>
Link: https://lore.kernel.org/r/20200506034050.24806-13-jniethe5@gmail.com

2 files changed, 16 insertions, 14 deletions

diff --git a/arch/powerpc/lib/code-patching.c b/arch/powerpc/lib/code-patching.c
index 1dff9d9d6645..435fc8e9f45d 100644
--- a/arch/powerpc/lib/code-patching.c
+++ b/arch/powerpc/lib/code-patching.c
@@ -348,9 +348,9 @@ static unsigned long branch_bform_target(const struct ppc_inst *instr)
 
 unsigned long branch_target(const struct ppc_inst *instr)
 {
-	if (instr_is_branch_iform(*instr))
+	if (instr_is_branch_iform(ppc_inst_read(instr)))
 		return branch_iform_target(instr);
-	else if (instr_is_branch_bform(*instr))
+	else if (instr_is_branch_bform(ppc_inst_read(instr)))
 		return branch_bform_target(instr);
 
 	return 0;
@@ -358,7 +358,8 @@ unsigned long branch_target(const struct ppc_inst *instr)
 
 int instr_is_branch_to_addr(const struct ppc_inst *instr, unsigned long addr)
 {
-	if (instr_is_branch_iform(*instr) || instr_is_branch_bform(*instr))
+	if (instr_is_branch_iform(ppc_inst_read(instr)) ||
+	    instr_is_branch_bform(ppc_inst_read(instr)))
 		return branch_target(instr) == addr;
 
 	return 0;
@@ -368,13 +369,14 @@ int translate_branch(struct ppc_inst *instr, const struct ppc_inst *dest,
 		     const struct ppc_inst *src)
 {
 	unsigned long target;
-
 	target = branch_target(src);
 
-	if (instr_is_branch_iform(*src))
-		return create_branch(instr, dest, target, ppc_inst_val(*src));
-	else if (instr_is_branch_bform(*src))
-		return create_cond_branch(instr, dest, target, ppc_inst_val(*src));
+	if (instr_is_branch_iform(ppc_inst_read(src)))
+		return create_branch(instr, dest, target,
+				     ppc_inst_val(ppc_inst_read(src)));
+	else if (instr_is_branch_bform(ppc_inst_read(src)))
+		return create_cond_branch(instr, dest, target,
+					  ppc_inst_val(ppc_inst_read(src)));
 
 	return 1;
 }
@@ -598,7 +600,7 @@ static void __init test_translate_branch(void)
 	patch_instruction(q, instr);
 	check(instr_is_branch_to_addr(p, addr));
 	check(instr_is_branch_to_addr(q, addr));
-	check(ppc_inst_equal(*q, ppc_inst(0x4a000000)));
+	check(ppc_inst_equal(ppc_inst_read(q), ppc_inst(0x4a000000)));
 
 	/* Maximum positive case, move x to x - 32 MB + 4 */
 	p = buf + 0x2000000;
@@ -609,7 +611,7 @@ static void __init test_translate_branch(void)
 	patch_instruction(q, instr);
 	check(instr_is_branch_to_addr(p, addr));
 	check(instr_is_branch_to_addr(q, addr));
-	check(ppc_inst_equal(*q, ppc_inst(0x49fffffc)));
+	check(ppc_inst_equal(ppc_inst_read(q), ppc_inst(0x49fffffc)));
 
 	/* Jump to x + 16 MB moved to x + 20 MB */
 	p = buf;
@@ -655,7 +657,7 @@ static void __init test_translate_branch(void)
 	patch_instruction(q, instr);
 	check(instr_is_branch_to_addr(p, addr));
 	check(instr_is_branch_to_addr(q, addr));
-	check(ppc_inst_equal(*q, ppc_inst(0x43ff8000)));
+	check(ppc_inst_equal(ppc_inst_read(q), ppc_inst(0x43ff8000)));
 
 	/* Maximum positive case, move x to x - 32 KB + 4 */
 	p = buf + 0x8000;
@@ -667,7 +669,7 @@ static void __init test_translate_branch(void)
 	patch_instruction(q, instr);
 	check(instr_is_branch_to_addr(p, addr));
 	check(instr_is_branch_to_addr(q, addr));
-	check(ppc_inst_equal(*q, ppc_inst(0x43ff7ffc)));
+	check(ppc_inst_equal(ppc_inst_read(q), ppc_inst(0x43ff7ffc)));
 
 	/* Jump to x + 12 KB moved to x + 20 KB */
 	p = buf;
diff --git a/arch/powerpc/lib/feature-fixups.c b/arch/powerpc/lib/feature-fixups.c
index fd978b8ee6d6..3c55097d406d 100644
--- a/arch/powerpc/lib/feature-fixups.c
+++ b/arch/powerpc/lib/feature-fixups.c
@@ -48,7 +48,7 @@ static int patch_alt_instruction(struct ppc_inst *src, struct ppc_inst *dest,
 	int err;
 	struct ppc_inst instr;
 
-	instr = *src;
+	instr = ppc_inst_read(src);
 
 	if (instr_is_relative_branch(*src)) {
 		struct ppc_inst *target = (struct ppc_inst *)branch_target(src);
@@ -403,7 +403,7 @@ static void do_final_fixups(void)
 	length = (__end_interrupts - _stext) / sizeof(struct ppc_inst);
 
 	while (length--) {
-		raw_patch_instruction(dest, *src);
+		raw_patch_instruction(dest, ppc_inst_read(src));
 		src++;
 		dest++;
 	}