powerpc/lib/code-patching: Don't use struct 'ppc_inst' for runnable code in tests.

'struct ppc_inst' is meant to represent an instruction internally, it
is not meant to dereference code in memory.

For testing code patching, use patch_instruction() to properly
write into memory the code to be tested.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/d8425fb42a4adebc35b7509f121817eeb02fac31.1621516826.git.christophe.leroy@csgroup.eu

arch/powerpc/lib/code-patching.c

@@ -422,9 +422,9 @@ static void __init test_branch_iform(void)
 {
 	int err;
 	struct ppc_inst instr;
-	unsigned long addr;
-
-	addr = (unsigned long)&instr;
+	u32 tmp[2];
+	struct ppc_inst *iptr = (struct ppc_inst *)tmp;
+	unsigned long addr = (unsigned long)tmp;
 
 	/* The simplest case, branch to self, no flags */
 	check(instr_is_branch_iform(ppc_inst(0x48000000)));
@@ -445,52 +445,57 @@ static void __init test_branch_iform(void)
 	check(!instr_is_branch_iform(ppc_inst(0x7bfffffd)));
 
 	/* Absolute branch to 0x100 */
-	instr = ppc_inst(0x48000103);
-	check(instr_is_branch_to_addr(&instr, 0x100));
+	patch_instruction(iptr, ppc_inst(0x48000103));
+	check(instr_is_branch_to_addr(iptr, 0x100));
 	/* Absolute branch to 0x420fc */
-	instr = ppc_inst(0x480420ff);
-	check(instr_is_branch_to_addr(&instr, 0x420fc));
+	patch_instruction(iptr, ppc_inst(0x480420ff));
+	check(instr_is_branch_to_addr(iptr, 0x420fc));
 	/* Maximum positive relative branch, + 20MB - 4B */
-	instr = ppc_inst(0x49fffffc);
-	check(instr_is_branch_to_addr(&instr, addr + 0x1FFFFFC));
+	patch_instruction(iptr, ppc_inst(0x49fffffc));
+	check(instr_is_branch_to_addr(iptr, addr + 0x1FFFFFC));
 	/* Smallest negative relative branch, - 4B */
-	instr = ppc_inst(0x4bfffffc);
-	check(instr_is_branch_to_addr(&instr, addr - 4));
+	patch_instruction(iptr, ppc_inst(0x4bfffffc));
+	check(instr_is_branch_to_addr(iptr, addr - 4));
 	/* Largest negative relative branch, - 32 MB */
-	instr = ppc_inst(0x4a000000);
-	check(instr_is_branch_to_addr(&instr, addr - 0x2000000));
+	patch_instruction(iptr, ppc_inst(0x4a000000));
+	check(instr_is_branch_to_addr(iptr, addr - 0x2000000));
 
 	/* Branch to self, with link */
-	err = create_branch(&instr, &instr, addr, BRANCH_SET_LINK);
-	check(instr_is_branch_to_addr(&instr, addr));
+	err = create_branch(&instr, iptr, addr, BRANCH_SET_LINK);
+	patch_instruction(iptr, instr);
+	check(instr_is_branch_to_addr(iptr, addr));
 
 	/* Branch to self - 0x100, with link */
-	err = create_branch(&instr, &instr, addr - 0x100, BRANCH_SET_LINK);
-	check(instr_is_branch_to_addr(&instr, addr - 0x100));
+	err = create_branch(&instr, iptr, addr - 0x100, BRANCH_SET_LINK);
+	patch_instruction(iptr, instr);
+	check(instr_is_branch_to_addr(iptr, addr - 0x100));
 
 	/* Branch to self + 0x100, no link */
-	err = create_branch(&instr, &instr, addr + 0x100, 0);
-	check(instr_is_branch_to_addr(&instr, addr + 0x100));
+	err = create_branch(&instr, iptr, addr + 0x100, 0);
+	patch_instruction(iptr, instr);
+	check(instr_is_branch_to_addr(iptr, addr + 0x100));
 
 	/* Maximum relative negative offset, - 32 MB */
-	err = create_branch(&instr, &instr, addr - 0x2000000, BRANCH_SET_LINK);
-	check(instr_is_branch_to_addr(&instr, addr - 0x2000000));
+	err = create_branch(&instr, iptr, addr - 0x2000000, BRANCH_SET_LINK);
+	patch_instruction(iptr, instr);
+	check(instr_is_branch_to_addr(iptr, addr - 0x2000000));
 
 	/* Out of range relative negative offset, - 32 MB + 4*/
-	err = create_branch(&instr, &instr, addr - 0x2000004, BRANCH_SET_LINK);
+	err = create_branch(&instr, iptr, addr - 0x2000004, BRANCH_SET_LINK);
 	check(err);
 
 	/* Out of range relative positive offset, + 32 MB */
-	err = create_branch(&instr, &instr, addr + 0x2000000, BRANCH_SET_LINK);
+	err = create_branch(&instr, iptr, addr + 0x2000000, BRANCH_SET_LINK);
 	check(err);
 
 	/* Unaligned target */
-	err = create_branch(&instr, &instr, addr + 3, BRANCH_SET_LINK);
+	err = create_branch(&instr, iptr, addr + 3, BRANCH_SET_LINK);
 	check(err);
 
 	/* Check flags are masked correctly */
-	err = create_branch(&instr, &instr, addr, 0xFFFFFFFC);
-	check(instr_is_branch_to_addr(&instr, addr));
+	err = create_branch(&instr, iptr, addr, 0xFFFFFFFC);
+	patch_instruction(iptr, instr);
+	check(instr_is_branch_to_addr(iptr, addr));
 	check(ppc_inst_equal(instr, ppc_inst(0x48000000)));
 }
 
@@ -513,9 +518,10 @@ static void __init test_branch_bform(void)
 	int err;
 	unsigned long addr;
 	struct ppc_inst *iptr, instr;
+	u32 tmp[2];
 	unsigned int flags;
 
-	iptr = &instr;
+	iptr = (struct ppc_inst *)tmp;
 	addr = (unsigned long)iptr;
 
 	/* The simplest case, branch to self, no flags */
@@ -528,39 +534,43 @@ static void __init test_branch_bform(void)
 	check(!instr_is_branch_bform(ppc_inst(0x7bffffff)));
 
 	/* Absolute conditional branch to 0x100 */
-	instr = ppc_inst(0x43ff0103);
-	check(instr_is_branch_to_addr(&instr, 0x100));
+	patch_instruction(iptr, ppc_inst(0x43ff0103));
+	check(instr_is_branch_to_addr(iptr, 0x100));
 	/* Absolute conditional branch to 0x20fc */
-	instr = ppc_inst(0x43ff20ff);
-	check(instr_is_branch_to_addr(&instr, 0x20fc));
+	patch_instruction(iptr, ppc_inst(0x43ff20ff));
+	check(instr_is_branch_to_addr(iptr, 0x20fc));
 	/* Maximum positive relative conditional branch, + 32 KB - 4B */
-	instr = ppc_inst(0x43ff7ffc);
-	check(instr_is_branch_to_addr(&instr, addr + 0x7FFC));
+	patch_instruction(iptr, ppc_inst(0x43ff7ffc));
+	check(instr_is_branch_to_addr(iptr, addr + 0x7FFC));
 	/* Smallest negative relative conditional branch, - 4B */
-	instr = ppc_inst(0x43fffffc);
-	check(instr_is_branch_to_addr(&instr, addr - 4));
+	patch_instruction(iptr, ppc_inst(0x43fffffc));
+	check(instr_is_branch_to_addr(iptr, addr - 4));
 	/* Largest negative relative conditional branch, - 32 KB */
-	instr = ppc_inst(0x43ff8000);
-	check(instr_is_branch_to_addr(&instr, addr - 0x8000));
+	patch_instruction(iptr, ppc_inst(0x43ff8000));
+	check(instr_is_branch_to_addr(iptr, addr - 0x8000));
 
 	/* All condition code bits set & link */
 	flags = 0x3ff000 | BRANCH_SET_LINK;
 
 	/* Branch to self */
 	err = create_cond_branch(&instr, iptr, addr, flags);
-	check(instr_is_branch_to_addr(&instr, addr));
+	patch_instruction(iptr, instr);
+	check(instr_is_branch_to_addr(iptr, addr));
 
 	/* Branch to self - 0x100 */
 	err = create_cond_branch(&instr, iptr, addr - 0x100, flags);
-	check(instr_is_branch_to_addr(&instr, addr - 0x100));
+	patch_instruction(iptr, instr);
+	check(instr_is_branch_to_addr(iptr, addr - 0x100));
 
 	/* Branch to self + 0x100 */
 	err = create_cond_branch(&instr, iptr, addr + 0x100, flags);
-	check(instr_is_branch_to_addr(&instr, addr + 0x100));
+	patch_instruction(iptr, instr);
+	check(instr_is_branch_to_addr(iptr, addr + 0x100));
 
 	/* Maximum relative negative offset, - 32 KB */
 	err = create_cond_branch(&instr, iptr, addr - 0x8000, flags);
-	check(instr_is_branch_to_addr(&instr, addr - 0x8000));
+	patch_instruction(iptr, instr);
+	check(instr_is_branch_to_addr(iptr, addr - 0x8000));
 
 	/* Out of range relative negative offset, - 32 KB + 4*/
 	err = create_cond_branch(&instr, iptr, addr - 0x8004, flags);
@@ -576,7 +586,8 @@ static void __init test_branch_bform(void)
 
 	/* Check flags are masked correctly */
 	err = create_cond_branch(&instr, iptr, addr, 0xFFFFFFFC);
-	check(instr_is_branch_to_addr(&instr, addr));
+	patch_instruction(iptr, instr);
+	check(instr_is_branch_to_addr(iptr, addr));
 	check(ppc_inst_equal(instr, ppc_inst(0x43FF0000)));
 }