[PATCH 3/3] powerpc/code-patching: don't use the stack for code patching tests

[Nicholas Piggin]

Use the existing test function for code patching tests instead of
writing to the stack. This means the address verification does not have
to be bypassed for these tests.

Signed-off-by: Nicholas Piggin <npig...@gmail.com>
---
 arch/powerpc/lib/code-patching.c | 24 ++++++++++++++++--------
 1 file changed, 16 insertions(+), 8 deletions(-)

diff --git a/arch/powerpc/lib/code-patching.c b/arch/powerpc/lib/code-patching.c
index 70247fc58b6e..babf6b22adef 100644
--- a/arch/powerpc/lib/code-patching.c
+++ b/arch/powerpc/lib/code-patching.c
@@ -422,9 +422,11 @@ static void __init test_branch_iform(void)
 {
        int err;
        struct ppc_inst instr;
-       u32 tmp[2];
-       u32 *iptr = tmp;
-       unsigned long addr = (unsigned long)tmp;
+       u32 *iptr;
+       unsigned long addr;
+
+       iptr = (u32 *)ppc_function_entry(test_trampoline);
+       addr = (unsigned long)iptr;
 
        /* The simplest case, branch to self, no flags */
        check(instr_is_branch_iform(ppc_inst(0x48000000)));
@@ -516,12 +518,12 @@ static void __init test_create_function_call(void)
 static void __init test_branch_bform(void)
 {
        int err;
-       unsigned long addr;
        struct ppc_inst instr;
-       u32 tmp[2];
-       u32 *iptr = tmp;
+       u32 *iptr;
+       unsigned long addr;
        unsigned int flags;
 
+       iptr = (u32 *)ppc_function_entry(test_trampoline);
        addr = (unsigned long)iptr;
 
        /* The simplest case, branch to self, no flags */
@@ -603,6 +605,12 @@ static void __init test_translate_branch(void)
        if (!buf)
                return;
 
+       /*
+        * Have to disable the address bounds check for patch_instruction
+        * because we are patching vmalloc space here.
+        */
+       skip_addr_verif = true;
+
        /* Simple case, branch to self moved a little */
        p = buf;
        addr = (unsigned long)p;
@@ -715,6 +723,8 @@ static void __init test_translate_branch(void)
        check(instr_is_branch_to_addr(p, addr));
        check(instr_is_branch_to_addr(q, addr));
 
+       skip_addr_verif = false;
+
        /* Free the buffer we were using */
        vfree(buf);
 }
@@ -743,13 +753,11 @@ static int __init test_code_patching(void)
 {
        printk(KERN_DEBUG "Running code patching self-tests ...\n");
 
-       skip_addr_verif = true;
        test_branch_iform();
        test_branch_bform();
        test_create_function_call();
        test_translate_branch();
        test_prefixed_patching();
-       skip_addr_verif = false;
 
        return 0;
 }
-- 
2.23.0