Adding upstream version 4.19.249.upstream/4.19.249upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 713 insertions, 0 deletions

diff --git a/arch/powerpc/lib/code-patching.c b/arch/powerpc/lib/code-patching.c
new file mode 100644
index 000000000..bb245dbf6
--- /dev/null
+++ b/arch/powerpc/lib/code-patching.c
@@ -0,0 +1,713 @@
+/*
+ *  Copyright 2008 Michael Ellerman, IBM Corporation.
+ *
+ *  This program is free software; you can redistribute it and/or
+ *  modify it under the terms of the GNU General Public License
+ *  as published by the Free Software Foundation; either version
+ *  2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/kernel.h>
+#include <linux/kprobes.h>
+#include <linux/vmalloc.h>
+#include <linux/init.h>
+#include <linux/mm.h>
+#include <linux/cpuhotplug.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+#include <linux/kprobes.h>
+
+#include <asm/pgtable.h>
+#include <asm/tlbflush.h>
+#include <asm/page.h>
+#include <asm/code-patching.h>
+#include <asm/setup.h>
+
+static int __patch_instruction(unsigned int *exec_addr, unsigned int instr,
+			       unsigned int *patch_addr)
+{
+	int err;
+
+	__put_user_size(instr, patch_addr, 4, err);
+	if (err)
+		return err;
+
+	asm ("dcbst 0, %0; sync; icbi 0,%1; sync; isync" :: "r" (patch_addr),
+							    "r" (exec_addr));
+
+	return 0;
+}
+
+int raw_patch_instruction(unsigned int *addr, unsigned int instr)
+{
+	return __patch_instruction(addr, instr, addr);
+}
+
+#ifdef CONFIG_STRICT_KERNEL_RWX
+static DEFINE_PER_CPU(struct vm_struct *, text_poke_area);
+
+static int text_area_cpu_up(unsigned int cpu)
+{
+	struct vm_struct *area;
+
+	area = get_vm_area(PAGE_SIZE, VM_ALLOC);
+	if (!area) {
+		WARN_ONCE(1, "Failed to create text area for cpu %d\n",
+			cpu);
+		return -1;
+	}
+	this_cpu_write(text_poke_area, area);
+
+	return 0;
+}
+
+static int text_area_cpu_down(unsigned int cpu)
+{
+	free_vm_area(this_cpu_read(text_poke_area));
+	return 0;
+}
+
+/*
+ * Run as a late init call. This allows all the boot time patching to be done
+ * simply by patching the code, and then we're called here prior to
+ * mark_rodata_ro(), which happens after all init calls are run. Although
+ * BUG_ON() is rude, in this case it should only happen if ENOMEM, and we judge
+ * it as being preferable to a kernel that will crash later when someone tries
+ * to use patch_instruction().
+ */
+static int __init setup_text_poke_area(void)
+{
+	BUG_ON(!cpuhp_setup_state(CPUHP_AP_ONLINE_DYN,
+		"powerpc/text_poke:online", text_area_cpu_up,
+		text_area_cpu_down));
+
+	return 0;
+}
+late_initcall(setup_text_poke_area);
+
+/*
+ * This can be called for kernel text or a module.
+ */
+static int map_patch_area(void *addr, unsigned long text_poke_addr)
+{
+	unsigned long pfn;
+	int err;
+
+	if (is_vmalloc_addr(addr))
+		pfn = vmalloc_to_pfn(addr);
+	else
+		pfn = __pa_symbol(addr) >> PAGE_SHIFT;
+
+	err = map_kernel_page(text_poke_addr, (pfn << PAGE_SHIFT),
+				pgprot_val(PAGE_KERNEL));
+
+	pr_devel("Mapped addr %lx with pfn %lx:%d\n", text_poke_addr, pfn, err);
+	if (err)
+		return -1;
+
+	return 0;
+}
+
+static inline int unmap_patch_area(unsigned long addr)
+{
+	pte_t *ptep;
+	pmd_t *pmdp;
+	pud_t *pudp;
+	pgd_t *pgdp;
+
+	pgdp = pgd_offset_k(addr);
+	if (unlikely(!pgdp))
+		return -EINVAL;
+
+	pudp = pud_offset(pgdp, addr);
+	if (unlikely(!pudp))
+		return -EINVAL;
+
+	pmdp = pmd_offset(pudp, addr);
+	if (unlikely(!pmdp))
+		return -EINVAL;
+
+	ptep = pte_offset_kernel(pmdp, addr);
+	if (unlikely(!ptep))
+		return -EINVAL;
+
+	pr_devel("clearing mm %p, pte %p, addr %lx\n", &init_mm, ptep, addr);
+
+	/*
+	 * In hash, pte_clear flushes the tlb, in radix, we have to
+	 */
+	pte_clear(&init_mm, addr, ptep);
+	flush_tlb_kernel_range(addr, addr + PAGE_SIZE);
+
+	return 0;
+}
+
+static int do_patch_instruction(unsigned int *addr, unsigned int instr)
+{
+	int err;
+	unsigned int *patch_addr = NULL;
+	unsigned long flags;
+	unsigned long text_poke_addr;
+	unsigned long kaddr = (unsigned long)addr;
+
+	/*
+	 * During early early boot patch_instruction is called
+	 * when text_poke_area is not ready, but we still need
+	 * to allow patching. We just do the plain old patching
+	 */
+	if (!this_cpu_read(text_poke_area))
+		return raw_patch_instruction(addr, instr);
+
+	local_irq_save(flags);
+
+	text_poke_addr = (unsigned long)__this_cpu_read(text_poke_area)->addr;
+	if (map_patch_area(addr, text_poke_addr)) {
+		err = -1;
+		goto out;
+	}
+
+	patch_addr = (unsigned int *)(text_poke_addr) +
+			((kaddr & ~PAGE_MASK) / sizeof(unsigned int));
+
+	__patch_instruction(addr, instr, patch_addr);
+
+	err = unmap_patch_area(text_poke_addr);
+	if (err)
+		pr_warn("failed to unmap %lx\n", text_poke_addr);
+
+out:
+	local_irq_restore(flags);
+
+	return err;
+}
+#else /* !CONFIG_STRICT_KERNEL_RWX */
+
+static int do_patch_instruction(unsigned int *addr, unsigned int instr)
+{
+	return raw_patch_instruction(addr, instr);
+}
+
+#endif /* CONFIG_STRICT_KERNEL_RWX */
+
+int patch_instruction(unsigned int *addr, unsigned int instr)
+{
+	/* Make sure we aren't patching a freed init section */
+	if (init_mem_is_free && init_section_contains(addr, 4)) {
+		pr_debug("Skipping init section patching addr: 0x%px\n", addr);
+		return 0;
+	}
+	return do_patch_instruction(addr, instr);
+}
+NOKPROBE_SYMBOL(patch_instruction);
+
+int patch_branch(unsigned int *addr, unsigned long target, int flags)
+{
+	return patch_instruction(addr, create_branch(addr, target, flags));
+}
+
+int patch_branch_site(s32 *site, unsigned long target, int flags)
+{
+	unsigned int *addr;
+
+	addr = (unsigned int *)((unsigned long)site + *site);
+	return patch_instruction(addr, create_branch(addr, target, flags));
+}
+
+int patch_instruction_site(s32 *site, unsigned int instr)
+{
+	unsigned int *addr;
+
+	addr = (unsigned int *)((unsigned long)site + *site);
+	return patch_instruction(addr, instr);
+}
+
+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));
+}
+
+bool is_offset_in_cond_branch_range(long offset)
+{
+	return offset >= -0x8000 && offset <= 0x7fff && !(offset & 0x3);
+}
+
+/*
+ * Helper to check if a given instruction is a conditional branch
+ * Derived from the conditional checks in analyse_instr()
+ */
+bool is_conditional_branch(unsigned int instr)
+{
+	unsigned int opcode = instr >> 26;
+
+	if (opcode == 16)       /* bc, bca, bcl, bcla */
+		return true;
+	if (opcode == 19) {
+		switch ((instr >> 1) & 0x3ff) {
+		case 16:        /* bclr, bclrl */
+		case 528:       /* bcctr, bcctrl */
+		case 560:       /* bctar, bctarl */
+			return true;
+		}
+	}
+	return false;
+}
+NOKPROBE_SYMBOL(is_conditional_branch);
+
+unsigned int create_branch(const unsigned int *addr,
+			   unsigned long target, int flags)
+{
+	unsigned int instruction;
+	long offset;
+
+	offset = target;
+	if (! (flags & BRANCH_ABSOLUTE))
+		offset = offset - (unsigned long)addr;
+
+	/* Check we can represent the target in the instruction format */
+	if (!is_offset_in_branch_range(offset))
+		return 0;
+
+	/* Mask out the flags and target, so they don't step on each other. */
+	instruction = 0x48000000 | (flags & 0x3) | (offset & 0x03FFFFFC);
+
+	return instruction;
+}
+
+unsigned int create_cond_branch(const unsigned int *addr,
+				unsigned long target, int flags)
+{
+	unsigned int instruction;
+	long offset;
+
+	offset = target;
+	if (! (flags & BRANCH_ABSOLUTE))
+		offset = offset - (unsigned long)addr;
+
+	/* Check we can represent the target in the instruction format */
+	if (!is_offset_in_cond_branch_range(offset))
+		return 0;
+
+	/* Mask out the flags and target, so they don't step on each other. */
+	instruction = 0x40000000 | (flags & 0x3FF0003) | (offset & 0xFFFC);
+
+	return instruction;
+}
+
+static unsigned int branch_opcode(unsigned int instr)
+{
+	return (instr >> 26) & 0x3F;
+}
+
+static int instr_is_branch_iform(unsigned int instr)
+{
+	return branch_opcode(instr) == 18;
+}
+
+static int instr_is_branch_bform(unsigned int instr)
+{
+	return branch_opcode(instr) == 16;
+}
+
+int instr_is_relative_branch(unsigned int instr)
+{
+	if (instr & BRANCH_ABSOLUTE)
+		return 0;
+
+	return instr_is_branch_iform(instr) || instr_is_branch_bform(instr);
+}
+
+int instr_is_relative_link_branch(unsigned int instr)
+{
+	return instr_is_relative_branch(instr) && (instr & BRANCH_SET_LINK);
+}
+
+static unsigned long branch_iform_target(const unsigned int *instr)
+{
+	signed long imm;
+
+	imm = *instr & 0x3FFFFFC;
+
+	/* If the top bit of the immediate value is set this is negative */
+	if (imm & 0x2000000)
+		imm -= 0x4000000;
+
+	if ((*instr & BRANCH_ABSOLUTE) == 0)
+		imm += (unsigned long)instr;
+
+	return (unsigned long)imm;
+}
+
+static unsigned long branch_bform_target(const unsigned int *instr)
+{
+	signed long imm;
+
+	imm = *instr & 0xFFFC;
+
+	/* If the top bit of the immediate value is set this is negative */
+	if (imm & 0x8000)
+		imm -= 0x10000;
+
+	if ((*instr & BRANCH_ABSOLUTE) == 0)
+		imm += (unsigned long)instr;
+
+	return (unsigned long)imm;
+}
+
+unsigned long branch_target(const unsigned int *instr)
+{
+	if (instr_is_branch_iform(*instr))
+		return branch_iform_target(instr);
+	else if (instr_is_branch_bform(*instr))
+		return branch_bform_target(instr);
+
+	return 0;
+}
+
+int instr_is_branch_to_addr(const unsigned int *instr, unsigned long addr)
+{
+	if (instr_is_branch_iform(*instr) || instr_is_branch_bform(*instr))
+		return branch_target(instr) == addr;
+
+	return 0;
+}
+
+unsigned int translate_branch(const unsigned int *dest, const unsigned int *src)
+{
+	unsigned long target;
+
+	target = branch_target(src);
+
+	if (instr_is_branch_iform(*src))
+		return create_branch(dest, target, *src);
+	else if (instr_is_branch_bform(*src))
+		return create_cond_branch(dest, target, *src);
+
+	return 0;
+}
+
+#ifdef CONFIG_PPC_BOOK3E_64
+void __patch_exception(int exc, unsigned long addr)
+{
+	extern unsigned int interrupt_base_book3e;
+	unsigned int *ibase = &interrupt_base_book3e;
+
+	/* Our exceptions vectors start with a NOP and -then- a branch
+	 * to deal with single stepping from userspace which stops on
+	 * the second instruction. Thus we need to patch the second
+	 * instruction of the exception, not the first one
+	 */
+
+	patch_branch(ibase + (exc / 4) + 1, addr, 0);
+}
+#endif
+
+#ifdef CONFIG_CODE_PATCHING_SELFTEST
+
+static void __init test_trampoline(void)
+{
+	asm ("nop;\n");
+}
+
+#define check(x)	\
+	if (!(x)) printk("code-patching: test failed at line %d\n", __LINE__);
+
+static void __init test_branch_iform(void)
+{
+	unsigned int instr;
+	unsigned long addr;
+
+	addr = (unsigned long)&instr;
+
+	/* The simplest case, branch to self, no flags */
+	check(instr_is_branch_iform(0x48000000));
+	/* All bits of target set, and flags */
+	check(instr_is_branch_iform(0x4bffffff));
+	/* High bit of opcode set, which is wrong */
+	check(!instr_is_branch_iform(0xcbffffff));
+	/* Middle bits of opcode set, which is wrong */
+	check(!instr_is_branch_iform(0x7bffffff));
+
+	/* Simplest case, branch to self with link */
+	check(instr_is_branch_iform(0x48000001));
+	/* All bits of targets set */
+	check(instr_is_branch_iform(0x4bfffffd));
+	/* Some bits of targets set */
+	check(instr_is_branch_iform(0x4bff00fd));
+	/* Must be a valid branch to start with */
+	check(!instr_is_branch_iform(0x7bfffffd));
+
+	/* Absolute branch to 0x100 */
+	instr = 0x48000103;
+	check(instr_is_branch_to_addr(&instr, 0x100));
+	/* Absolute branch to 0x420fc */
+	instr = 0x480420ff;
+	check(instr_is_branch_to_addr(&instr, 0x420fc));
+	/* Maximum positive relative branch, + 20MB - 4B */
+	instr = 0x49fffffc;
+	check(instr_is_branch_to_addr(&instr, addr + 0x1FFFFFC));
+	/* Smallest negative relative branch, - 4B */
+	instr = 0x4bfffffc;
+	check(instr_is_branch_to_addr(&instr, addr - 4));
+	/* Largest negative relative branch, - 32 MB */
+	instr = 0x4a000000;
+	check(instr_is_branch_to_addr(&instr, addr - 0x2000000));
+
+	/* Branch to self, with link */
+	instr = create_branch(&instr, addr, BRANCH_SET_LINK);
+	check(instr_is_branch_to_addr(&instr, addr));
+
+	/* Branch to self - 0x100, with link */
+	instr = create_branch(&instr, addr - 0x100, BRANCH_SET_LINK);
+	check(instr_is_branch_to_addr(&instr, addr - 0x100));
+
+	/* Branch to self + 0x100, no link */
+	instr = create_branch(&instr, addr + 0x100, 0);
+	check(instr_is_branch_to_addr(&instr, addr + 0x100));
+
+	/* Maximum relative negative offset, - 32 MB */
+	instr = create_branch(&instr, addr - 0x2000000, BRANCH_SET_LINK);
+	check(instr_is_branch_to_addr(&instr, addr - 0x2000000));
+
+	/* Out of range relative negative offset, - 32 MB + 4*/
+	instr = create_branch(&instr, addr - 0x2000004, BRANCH_SET_LINK);
+	check(instr == 0);
+
+	/* Out of range relative positive offset, + 32 MB */
+	instr = create_branch(&instr, addr + 0x2000000, BRANCH_SET_LINK);
+	check(instr == 0);
+
+	/* Unaligned target */
+	instr = create_branch(&instr, addr + 3, BRANCH_SET_LINK);
+	check(instr == 0);
+
+	/* Check flags are masked correctly */
+	instr = create_branch(&instr, addr, 0xFFFFFFFC);
+	check(instr_is_branch_to_addr(&instr, addr));
+	check(instr == 0x48000000);
+}
+
+static void __init test_create_function_call(void)
+{
+	unsigned int *iptr;
+	unsigned long dest;
+
+	/* Check we can create a function call */
+	iptr = (unsigned int *)ppc_function_entry(test_trampoline);
+	dest = ppc_function_entry(test_create_function_call);
+	patch_instruction(iptr, create_branch(iptr, dest, BRANCH_SET_LINK));
+	check(instr_is_branch_to_addr(iptr, dest));
+}
+
+static void __init test_branch_bform(void)
+{
+	unsigned long addr;
+	unsigned int *iptr, instr, flags;
+
+	iptr = &instr;
+	addr = (unsigned long)iptr;
+
+	/* The simplest case, branch to self, no flags */
+	check(instr_is_branch_bform(0x40000000));
+	/* All bits of target set, and flags */
+	check(instr_is_branch_bform(0x43ffffff));
+	/* High bit of opcode set, which is wrong */
+	check(!instr_is_branch_bform(0xc3ffffff));
+	/* Middle bits of opcode set, which is wrong */
+	check(!instr_is_branch_bform(0x7bffffff));
+
+	/* Absolute conditional branch to 0x100 */
+	instr = 0x43ff0103;
+	check(instr_is_branch_to_addr(&instr, 0x100));
+	/* Absolute conditional branch to 0x20fc */
+	instr = 0x43ff20ff;
+	check(instr_is_branch_to_addr(&instr, 0x20fc));
+	/* Maximum positive relative conditional branch, + 32 KB - 4B */
+	instr = 0x43ff7ffc;
+	check(instr_is_branch_to_addr(&instr, addr + 0x7FFC));
+	/* Smallest negative relative conditional branch, - 4B */
+	instr = 0x43fffffc;
+	check(instr_is_branch_to_addr(&instr, addr - 4));
+	/* Largest negative relative conditional branch, - 32 KB */
+	instr = 0x43ff8000;
+	check(instr_is_branch_to_addr(&instr, addr - 0x8000));
+
+	/* All condition code bits set & link */
+	flags = 0x3ff000 | BRANCH_SET_LINK;
+
+	/* Branch to self */
+	instr = create_cond_branch(iptr, addr, flags);
+	check(instr_is_branch_to_addr(&instr, addr));
+
+	/* Branch to self - 0x100 */
+	instr = create_cond_branch(iptr, addr - 0x100, flags);
+	check(instr_is_branch_to_addr(&instr, addr - 0x100));
+
+	/* Branch to self + 0x100 */
+	instr = create_cond_branch(iptr, addr + 0x100, flags);
+	check(instr_is_branch_to_addr(&instr, addr + 0x100));
+
+	/* Maximum relative negative offset, - 32 KB */
+	instr = create_cond_branch(iptr, addr - 0x8000, flags);
+	check(instr_is_branch_to_addr(&instr, addr - 0x8000));
+
+	/* Out of range relative negative offset, - 32 KB + 4*/
+	instr = create_cond_branch(iptr, addr - 0x8004, flags);
+	check(instr == 0);
+
+	/* Out of range relative positive offset, + 32 KB */
+	instr = create_cond_branch(iptr, addr + 0x8000, flags);
+	check(instr == 0);
+
+	/* Unaligned target */
+	instr = create_cond_branch(iptr, addr + 3, flags);
+	check(instr == 0);
+
+	/* Check flags are masked correctly */
+	instr = create_cond_branch(iptr, addr, 0xFFFFFFFC);
+	check(instr_is_branch_to_addr(&instr, addr));
+	check(instr == 0x43FF0000);
+}
+
+static void __init test_translate_branch(void)
+{
+	unsigned long addr;
+	unsigned int *p, *q;
+	void *buf;
+
+	buf = vmalloc(PAGE_ALIGN(0x2000000 + 1));
+	check(buf);
+	if (!buf)
+		return;
+
+	/* Simple case, branch to self moved a little */
+	p = buf;
+	addr = (unsigned long)p;
+	patch_branch(p, addr, 0);
+	check(instr_is_branch_to_addr(p, addr));
+	q = p + 1;
+	patch_instruction(q, translate_branch(q, p));
+	check(instr_is_branch_to_addr(q, addr));
+
+	/* Maximum negative case, move b . to addr + 32 MB */
+	p = buf;
+	addr = (unsigned long)p;
+	patch_branch(p, addr, 0);
+	q = buf + 0x2000000;
+	patch_instruction(q, translate_branch(q, p));
+	check(instr_is_branch_to_addr(p, addr));
+	check(instr_is_branch_to_addr(q, addr));
+	check(*q == 0x4a000000);
+
+	/* Maximum positive case, move x to x - 32 MB + 4 */
+	p = buf + 0x2000000;
+	addr = (unsigned long)p;
+	patch_branch(p, addr, 0);
+	q = buf + 4;
+	patch_instruction(q, translate_branch(q, p));
+	check(instr_is_branch_to_addr(p, addr));
+	check(instr_is_branch_to_addr(q, addr));
+	check(*q == 0x49fffffc);
+
+	/* Jump to x + 16 MB moved to x + 20 MB */
+	p = buf;
+	addr = 0x1000000 + (unsigned long)buf;
+	patch_branch(p, addr, BRANCH_SET_LINK);
+	q = buf + 0x1400000;
+	patch_instruction(q, translate_branch(q, p));
+	check(instr_is_branch_to_addr(p, addr));
+	check(instr_is_branch_to_addr(q, addr));
+
+	/* Jump to x + 16 MB moved to x - 16 MB + 4 */
+	p = buf + 0x1000000;
+	addr = 0x2000000 + (unsigned long)buf;
+	patch_branch(p, addr, 0);
+	q = buf + 4;
+	patch_instruction(q, translate_branch(q, p));
+	check(instr_is_branch_to_addr(p, addr));
+	check(instr_is_branch_to_addr(q, addr));
+
+
+	/* Conditional branch tests */
+
+	/* Simple case, branch to self moved a little */
+	p = buf;
+	addr = (unsigned long)p;
+	patch_instruction(p, create_cond_branch(p, addr, 0));
+	check(instr_is_branch_to_addr(p, addr));
+	q = p + 1;
+	patch_instruction(q, translate_branch(q, p));
+	check(instr_is_branch_to_addr(q, addr));
+
+	/* Maximum negative case, move b . to addr + 32 KB */
+	p = buf;
+	addr = (unsigned long)p;
+	patch_instruction(p, create_cond_branch(p, addr, 0xFFFFFFFC));
+	q = buf + 0x8000;
+	patch_instruction(q, translate_branch(q, p));
+	check(instr_is_branch_to_addr(p, addr));
+	check(instr_is_branch_to_addr(q, addr));
+	check(*q == 0x43ff8000);
+
+	/* Maximum positive case, move x to x - 32 KB + 4 */
+	p = buf + 0x8000;
+	addr = (unsigned long)p;
+	patch_instruction(p, create_cond_branch(p, addr, 0xFFFFFFFC));
+	q = buf + 4;
+	patch_instruction(q, translate_branch(q, p));
+	check(instr_is_branch_to_addr(p, addr));
+	check(instr_is_branch_to_addr(q, addr));
+	check(*q == 0x43ff7ffc);
+
+	/* Jump to x + 12 KB moved to x + 20 KB */
+	p = buf;
+	addr = 0x3000 + (unsigned long)buf;
+	patch_instruction(p, create_cond_branch(p, addr, BRANCH_SET_LINK));
+	q = buf + 0x5000;
+	patch_instruction(q, translate_branch(q, p));
+	check(instr_is_branch_to_addr(p, addr));
+	check(instr_is_branch_to_addr(q, addr));
+
+	/* Jump to x + 8 KB moved to x - 8 KB + 4 */
+	p = buf + 0x2000;
+	addr = 0x4000 + (unsigned long)buf;
+	patch_instruction(p, create_cond_branch(p, addr, 0));
+	q = buf + 4;
+	patch_instruction(q, translate_branch(q, p));
+	check(instr_is_branch_to_addr(p, addr));
+	check(instr_is_branch_to_addr(q, addr));
+
+	/* Free the buffer we were using */
+	vfree(buf);
+}
+
+static int __init test_code_patching(void)
+{
+	printk(KERN_DEBUG "Running code patching self-tests ...\n");
+
+	test_branch_iform();
+	test_branch_bform();
+	test_create_function_call();
+	test_translate_branch();
+
+	return 0;
+}
+late_initcall(test_code_patching);
+
+#endif /* CONFIG_CODE_PATCHING_SELFTEST */