[linux-2.6-block.git] / arch / powerpc / lib / code-patching.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  Copyright 2008 Michael Ellerman, IBM Corporation.
 */

#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 <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 = 0;

	__put_user_asm(instr, patch_addr, err, "stw");
	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), 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));
}

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));
}

/*
 * 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 (offset < -0x8000 || offset > 0x7FFF || offset & 0x3)
		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 */
Commit	Line	Data
2874c5fd	1	// SPDX-License-Identifier: GPL-2.0-or-later
aaddd3ea ME	2	/*
aaddd3ea ME	3	* Copyright 2008 Michael Ellerman, IBM Corporation.
aaddd3ea ME	4	*/
	5
	6	#include <linux/kernel.h>
71f6e58e	7	#include <linux/kprobes.h>
ae0dc736 ME	8	#include <linux/vmalloc.h>
ae0dc736 ME	9	#include <linux/init.h>
27ac792c	10	#include <linux/mm.h>
37bc3e5f BS	11	#include <linux/cpuhotplug.h>
37bc3e5f BS	12	#include <linux/slab.h>
7c0f6ba6	13	#include <linux/uaccess.h>
aaddd3ea	14
37bc3e5f BS	15	#include <asm/pgtable.h>
	16	#include <asm/tlbflush.h>
	17	#include <asm/page.h>
	18	#include <asm/code-patching.h>
252eb558	19	#include <asm/setup.h>
aaddd3ea	20
8cf4c057 CL	21	static int __patch_instruction(unsigned int *exec_addr, unsigned int instr,
8cf4c057 CL	22	unsigned int *patch_addr)
aaddd3ea	23	{
ef296729	24	int err = 0;
b6e37968	25
ef296729	26	__put_user_asm(instr, patch_addr, err, "stw");
b6e37968 SR	27	if (err)
b6e37968 SR	28	return err;
37bc3e5f	29
8cf4c057 CL	30	asm ("dcbst 0, %0; sync; icbi 0,%1; sync; isync" :: "r" (patch_addr),
8cf4c057 CL	31	"r" (exec_addr));
37bc3e5f BS	32
	33	return 0;
	34	}
	35
8183d99f	36	int raw_patch_instruction(unsigned int *addr, unsigned int instr)
8cf4c057 CL	37	{
	38	return __patch_instruction(addr, instr, addr);
	39	}
	40
37bc3e5f BS	41	#ifdef CONFIG_STRICT_KERNEL_RWX
	42	static DEFINE_PER_CPU(struct vm_struct *, text_poke_area);
	43
	44	static int text_area_cpu_up(unsigned int cpu)
	45	{
	46	struct vm_struct *area;
	47
	48	area = get_vm_area(PAGE_SIZE, VM_ALLOC);
	49	if (!area) {
	50	WARN_ONCE(1, "Failed to create text area for cpu %d\n",
	51	cpu);
	52	return -1;
	53	}
	54	this_cpu_write(text_poke_area, area);
	55
	56	return 0;
	57	}
	58
	59	static int text_area_cpu_down(unsigned int cpu)
	60	{
	61	free_vm_area(this_cpu_read(text_poke_area));
	62	return 0;
	63	}
	64
	65	/*
	66	* Run as a late init call. This allows all the boot time patching to be done
	67	* simply by patching the code, and then we're called here prior to
	68	* mark_rodata_ro(), which happens after all init calls are run. Although
	69	* BUG_ON() is rude, in this case it should only happen if ENOMEM, and we judge
	70	* it as being preferable to a kernel that will crash later when someone tries
	71	* to use patch_instruction().
	72	*/
	73	static int __init setup_text_poke_area(void)
	74	{
	75	BUG_ON(!cpuhp_setup_state(CPUHP_AP_ONLINE_DYN,
	76	"powerpc/text_poke:online", text_area_cpu_up,
	77	text_area_cpu_down));
	78
	79	return 0;
	80	}
	81	late_initcall(setup_text_poke_area);
	82
	83	/*
	84	* This can be called for kernel text or a module.
	85	*/
	86	static int map_patch_area(void *addr, unsigned long text_poke_addr)
	87	{
	88	unsigned long pfn;
	89	int err;
	90
	91	if (is_vmalloc_addr(addr))
	92	pfn = vmalloc_to_pfn(addr);
	93	else
	94	pfn = __pa_symbol(addr) >> PAGE_SHIFT;
	95
c766ee72	96	err = map_kernel_page(text_poke_addr, (pfn << PAGE_SHIFT), PAGE_KERNEL);
37bc3e5f BS	97
	98	pr_devel("Mapped addr %lx with pfn %lx:%d\n", text_poke_addr, pfn, err);
	99	if (err)
	100	return -1;
	101
	102	return 0;
	103	}
	104
	105	static inline int unmap_patch_area(unsigned long addr)
	106	{
	107	pte_t *ptep;
	108	pmd_t *pmdp;
	109	pud_t *pudp;
	110	pgd_t *pgdp;
	111
	112	pgdp = pgd_offset_k(addr);
	113	if (unlikely(!pgdp))
	114	return -EINVAL;
	115
	116	pudp = pud_offset(pgdp, addr);
	117	if (unlikely(!pudp))
	118	return -EINVAL;
	119
	120	pmdp = pmd_offset(pudp, addr);
	121	if (unlikely(!pmdp))
	122	return -EINVAL;
	123
	124	ptep = pte_offset_kernel(pmdp, addr);
	125	if (unlikely(!ptep))
	126	return -EINVAL;
	127
	128	pr_devel("clearing mm %p, pte %p, addr %lx\n", &init_mm, ptep, addr);
	129
	130	/*
	131	* In hash, pte_clear flushes the tlb, in radix, we have to
	132	*/
	133	pte_clear(&init_mm, addr, ptep);
	134	flush_tlb_kernel_range(addr, addr + PAGE_SIZE);
	135
b6e37968	136	return 0;
aaddd3ea ME	137	}
aaddd3ea ME	138
b45ba4a5	139	static int do_patch_instruction(unsigned int *addr, unsigned int instr)
37bc3e5f BS	140	{
37bc3e5f BS	141	int err;
8cf4c057	142	unsigned int *patch_addr = NULL;
37bc3e5f BS	143	unsigned long flags;
	144	unsigned long text_poke_addr;
	145	unsigned long kaddr = (unsigned long)addr;
	146
	147	/*
	148	* During early early boot patch_instruction is called
	149	* when text_poke_area is not ready, but we still need
	150	* to allow patching. We just do the plain old patching
37bc3e5f	151	*/
8183d99f	152	if (!this_cpu_read(text_poke_area))
8cf4c057	153	return raw_patch_instruction(addr, instr);
37bc3e5f BS	154
	155	local_irq_save(flags);
	156
	157	text_poke_addr = (unsigned long)__this_cpu_read(text_poke_area)->addr;
	158	if (map_patch_area(addr, text_poke_addr)) {
	159	err = -1;
	160	goto out;
	161	}
	162
8cf4c057	163	patch_addr = (unsigned int *)(text_poke_addr) +
37bc3e5f BS	164	((kaddr & ~PAGE_MASK) / sizeof(unsigned int));
37bc3e5f BS	165
8cf4c057	166	__patch_instruction(addr, instr, patch_addr);
37bc3e5f BS	167
	168	err = unmap_patch_area(text_poke_addr);
	169	if (err)
	170	pr_warn("failed to unmap %lx\n", text_poke_addr);
	171
	172	out:
	173	local_irq_restore(flags);
	174
	175	return err;
	176	}
	177	#else /* !CONFIG_STRICT_KERNEL_RWX */
	178
b45ba4a5	179	static int do_patch_instruction(unsigned int *addr, unsigned int instr)
37bc3e5f	180	{
8cf4c057	181	return raw_patch_instruction(addr, instr);
37bc3e5f BS	182	}
	183
	184	#endif /* CONFIG_STRICT_KERNEL_RWX */
b45ba4a5 CL	185
	186	int patch_instruction(unsigned int *addr, unsigned int instr)
	187	{
	188	/* Make sure we aren't patching a freed init section */
	189	if (init_mem_is_free && init_section_contains(addr, 4)) {
	190	pr_debug("Skipping init section patching addr: 0x%px\n", addr);
	191	return 0;
	192	}
	193	return do_patch_instruction(addr, instr);
	194	}
37bc3e5f BS	195	NOKPROBE_SYMBOL(patch_instruction);
37bc3e5f BS	196
b6e37968	197	int patch_branch(unsigned int *addr, unsigned long target, int flags)
e7a57273	198	{
b6e37968	199	return patch_instruction(addr, create_branch(addr, target, flags));
e7a57273 ME	200	}
e7a57273 ME	201
ebfa50df A	202	bool is_offset_in_branch_range(long offset)
	203	{
	204	/*
	205	* Powerpc branch instruction is :
	206	*
	207	* 0 6 30 31
	208	* +---------+----------------+---+---+
	209	* \| opcode \| LI \|AA \|LK \|
	210	* +---------+----------------+---+---+
	211	* Where AA = 0 and LK = 0
	212	*
	213	* LI is a signed 24 bits integer. The real branch offset is computed
	214	* by: imm32 = SignExtend(LI:'0b00', 32);
	215	*
	216	* So the maximum forward branch should be:
	217	* (0x007fffff << 2) = 0x01fffffc = 0x1fffffc
	218	* The maximum backward branch should be:
	219	* (0xff800000 << 2) = 0xfe000000 = -0x2000000
	220	*/
	221	return (offset >= -0x2000000 && offset <= 0x1fffffc && !(offset & 0x3));
	222	}
	223
51c9c084 A	224	/*
	225	* Helper to check if a given instruction is a conditional branch
	226	* Derived from the conditional checks in analyse_instr()
	227	*/
71f6e58e	228	bool is_conditional_branch(unsigned int instr)
51c9c084 A	229	{
	230	unsigned int opcode = instr >> 26;
	231
	232	if (opcode == 16) /* bc, bca, bcl, bcla */
	233	return true;
	234	if (opcode == 19) {
	235	switch ((instr >> 1) & 0x3ff) {
	236	case 16: /* bclr, bclrl */
	237	case 528: /* bcctr, bcctrl */
	238	case 560: /* bctar, bctarl */
	239	return true;
	240	}
	241	}
	242	return false;
	243	}
71f6e58e	244	NOKPROBE_SYMBOL(is_conditional_branch);
51c9c084	245
e7a57273 ME	246	unsigned int create_branch(const unsigned int *addr,
e7a57273 ME	247	unsigned long target, int flags)
aaddd3ea ME	248	{
aaddd3ea ME	249	unsigned int instruction;
053a858e	250	long offset;
aaddd3ea	251
053a858e	252	offset = target;
aaddd3ea	253	if (! (flags & BRANCH_ABSOLUTE))
053a858e ME	254	offset = offset - (unsigned long)addr;
	255
	256	/* Check we can represent the target in the instruction format */
ebfa50df	257	if (!is_offset_in_branch_range(offset))
053a858e	258	return 0;
aaddd3ea ME	259
aaddd3ea ME	260	/* Mask out the flags and target, so they don't step on each other. */
053a858e	261	instruction = 0x48000000 \| (flags & 0x3) \| (offset & 0x03FFFFFC);
aaddd3ea	262
e7a57273	263	return instruction;
aaddd3ea	264	}
411781a2 ME	265
	266	unsigned int create_cond_branch(const unsigned int *addr,
	267	unsigned long target, int flags)
	268	{
	269	unsigned int instruction;
	270	long offset;
	271
	272	offset = target;
	273	if (! (flags & BRANCH_ABSOLUTE))
	274	offset = offset - (unsigned long)addr;
	275
	276	/* Check we can represent the target in the instruction format */
	277	if (offset < -0x8000 \|\| offset > 0x7FFF \|\| offset & 0x3)
	278	return 0;
	279
	280	/* Mask out the flags and target, so they don't step on each other. */
	281	instruction = 0x40000000 \| (flags & 0x3FF0003) \| (offset & 0xFFFC);
	282
	283	return instruction;
	284	}
	285
	286	static unsigned int branch_opcode(unsigned int instr)
	287	{
	288	return (instr >> 26) & 0x3F;
	289	}
	290
	291	static int instr_is_branch_iform(unsigned int instr)
	292	{
	293	return branch_opcode(instr) == 18;
	294	}
	295
	296	static int instr_is_branch_bform(unsigned int instr)
	297	{
	298	return branch_opcode(instr) == 16;
	299	}
	300
	301	int instr_is_relative_branch(unsigned int instr)
	302	{
	303	if (instr & BRANCH_ABSOLUTE)
	304	return 0;
	305
	306	return instr_is_branch_iform(instr) \|\| instr_is_branch_bform(instr);
	307	}
	308
b9eab08d JP	309	int instr_is_relative_link_branch(unsigned int instr)
	310	{
	311	return instr_is_relative_branch(instr) && (instr & BRANCH_SET_LINK);
	312	}
	313
411781a2 ME	314	static unsigned long branch_iform_target(const unsigned int *instr)
	315	{
	316	signed long imm;
	317
	318	imm = *instr & 0x3FFFFFC;
	319
	320	/* If the top bit of the immediate value is set this is negative */
	321	if (imm & 0x2000000)
	322	imm -= 0x4000000;
	323
	324	if ((*instr & BRANCH_ABSOLUTE) == 0)
	325	imm += (unsigned long)instr;
	326
	327	return (unsigned long)imm;
	328	}
	329
	330	static unsigned long branch_bform_target(const unsigned int *instr)
	331	{
	332	signed long imm;
	333
	334	imm = *instr & 0xFFFC;
	335
	336	/* If the top bit of the immediate value is set this is negative */
	337	if (imm & 0x8000)
	338	imm -= 0x10000;
	339
	340	if ((*instr & BRANCH_ABSOLUTE) == 0)
	341	imm += (unsigned long)instr;
	342
	343	return (unsigned long)imm;
	344	}
	345
	346	unsigned long branch_target(const unsigned int *instr)
	347	{
	348	if (instr_is_branch_iform(*instr))
	349	return branch_iform_target(instr);
	350	else if (instr_is_branch_bform(*instr))
	351	return branch_bform_target(instr);
	352
	353	return 0;
	354	}
	355
	356	int instr_is_branch_to_addr(const unsigned int *instr, unsigned long addr)
	357	{
	358	if (instr_is_branch_iform(instr) \|\| instr_is_branch_bform(instr))
	359	return branch_target(instr) == addr;
	360
	361	return 0;
	362	}
	363
	364	unsigned int translate_branch(const unsigned int dest, const unsigned int src)
	365	{
	366	unsigned long target;
	367
	368	target = branch_target(src);
	369
	370	if (instr_is_branch_iform(*src))
	371	return create_branch(dest, target, *src);
	372	else if (instr_is_branch_bform(*src))
	373	return create_cond_branch(dest, target, *src);
	374
	375	return 0;
	376	}
ae0dc736	377
1e8341ae KH	378	#ifdef CONFIG_PPC_BOOK3E_64
	379	void __patch_exception(int exc, unsigned long addr)
	380	{
	381	extern unsigned int interrupt_base_book3e;
	382	unsigned int *ibase = &interrupt_base_book3e;
	383
	384	/* Our exceptions vectors start with a NOP and -then- a branch
	385	* to deal with single stepping from userspace which stops on
	386	* the second instruction. Thus we need to patch the second
	387	* instruction of the exception, not the first one
	388	*/
	389
	390	patch_branch(ibase + (exc / 4) + 1, addr, 0);
	391	}
	392	#endif
ae0dc736 ME	393
	394	#ifdef CONFIG_CODE_PATCHING_SELFTEST
	395
	396	static void __init test_trampoline(void)
	397	{
	398	asm ("nop;\n");
	399	}
	400
	401	#define check(x) \
	402	if (!(x)) printk("code-patching: test failed at line %d\n", __LINE__);
	403
	404	static void __init test_branch_iform(void)
	405	{
	406	unsigned int instr;
	407	unsigned long addr;
	408
	409	addr = (unsigned long)&instr;
	410
	411	/* The simplest case, branch to self, no flags */
	412	check(instr_is_branch_iform(0x48000000));
	413	/* All bits of target set, and flags */
	414	check(instr_is_branch_iform(0x4bffffff));
	415	/* High bit of opcode set, which is wrong */
	416	check(!instr_is_branch_iform(0xcbffffff));
	417	/* Middle bits of opcode set, which is wrong */
	418	check(!instr_is_branch_iform(0x7bffffff));
	419
	420	/* Simplest case, branch to self with link */
	421	check(instr_is_branch_iform(0x48000001));
	422	/* All bits of targets set */
	423	check(instr_is_branch_iform(0x4bfffffd));
	424	/* Some bits of targets set */
	425	check(instr_is_branch_iform(0x4bff00fd));
	426	/* Must be a valid branch to start with */
	427	check(!instr_is_branch_iform(0x7bfffffd));
	428
	429	/* Absolute branch to 0x100 */
	430	instr = 0x48000103;
	431	check(instr_is_branch_to_addr(&instr, 0x100));
	432	/* Absolute branch to 0x420fc */
	433	instr = 0x480420ff;
	434	check(instr_is_branch_to_addr(&instr, 0x420fc));
	435	/* Maximum positive relative branch, + 20MB - 4B */
	436	instr = 0x49fffffc;
	437	check(instr_is_branch_to_addr(&instr, addr + 0x1FFFFFC));
	438	/* Smallest negative relative branch, - 4B */
	439	instr = 0x4bfffffc;
	440	check(instr_is_branch_to_addr(&instr, addr - 4));
	441	/* Largest negative relative branch, - 32 MB */
	442	instr = 0x4a000000;
	443	check(instr_is_branch_to_addr(&instr, addr - 0x2000000));
	444
	445	/* Branch to self, with link */
	446	instr = create_branch(&instr, addr, BRANCH_SET_LINK);
	447	check(instr_is_branch_to_addr(&instr, addr));
	448
	449	/* Branch to self - 0x100, with link */
	450	instr = create_branch(&instr, addr - 0x100, BRANCH_SET_LINK);
	451	check(instr_is_branch_to_addr(&instr, addr - 0x100));
	452
	453	/* Branch to self + 0x100, no link */
	454	instr = create_branch(&instr, addr + 0x100, 0);
	455	check(instr_is_branch_to_addr(&instr, addr + 0x100));
	456
457	/* Maximum relative negative offset, - 32 MB */
458	instr = create_branch(&instr, addr - 0x2000000, BRANCH_SET_LINK);
459	check(instr_is_branch_to_addr(&instr, addr - 0x2000000));
460
461	/* Out of range relative negative offset, - 32 MB + 4*/
462	instr = create_branch(&instr, addr - 0x2000004, BRANCH_SET_LINK);
463	check(instr == 0);
464
465	/* Out of range relative positive offset, + 32 MB */
466	instr = create_branch(&instr, addr + 0x2000000, BRANCH_SET_LINK);
467	check(instr == 0);
468
469	/* Unaligned target */
470	instr = create_branch(&instr, addr + 3, BRANCH_SET_LINK);
471	check(instr == 0);
472
473	/* Check flags are masked correctly */
474	instr = create_branch(&instr, addr, 0xFFFFFFFC);
475	check(instr_is_branch_to_addr(&instr, addr));
476	check(instr == 0x48000000);
477	}
478
479	static void __init test_create_function_call(void)
480	{
481	unsigned int *iptr;
482	unsigned long dest;
483
484	/* Check we can create a function call */
485	iptr = (unsigned int *)ppc_function_entry(test_trampoline);
486	dest = ppc_function_entry(test_create_function_call);
487	patch_instruction(iptr, create_branch(iptr, dest, BRANCH_SET_LINK));
488	check(instr_is_branch_to_addr(iptr, dest));
489	}
490
491	static void __init test_branch_bform(void)
492	{
493	unsigned long addr;
494	unsigned int *iptr, instr, flags;
495
496	iptr = &instr;
497	addr = (unsigned long)iptr;
498
499	/* The simplest case, branch to self, no flags */
500	check(instr_is_branch_bform(0x40000000));
501	/* All bits of target set, and flags */
502	check(instr_is_branch_bform(0x43ffffff));
503	/* High bit of opcode set, which is wrong */
504	check(!instr_is_branch_bform(0xc3ffffff));
505	/* Middle bits of opcode set, which is wrong */
506	check(!instr_is_branch_bform(0x7bffffff));
507
508	/* Absolute conditional branch to 0x100 */
509	instr = 0x43ff0103;
510	check(instr_is_branch_to_addr(&instr, 0x100));
511	/* Absolute conditional branch to 0x20fc */
512	instr = 0x43ff20ff;
513	check(instr_is_branch_to_addr(&instr, 0x20fc));
514	/* Maximum positive relative conditional branch, + 32 KB - 4B */
515	instr = 0x43ff7ffc;
516	check(instr_is_branch_to_addr(&instr, addr + 0x7FFC));
517	/* Smallest negative relative conditional branch, - 4B */
518	instr = 0x43fffffc;
519	check(instr_is_branch_to_addr(&instr, addr - 4));
520	/* Largest negative relative conditional branch, - 32 KB */
521	instr = 0x43ff8000;
522	check(instr_is_branch_to_addr(&instr, addr - 0x8000));
523
524	/* All condition code bits set & link */
525	flags = 0x3ff000 \| BRANCH_SET_LINK;
526
527	/* Branch to self */
528	instr = create_cond_branch(iptr, addr, flags);
529	check(instr_is_branch_to_addr(&instr, addr));
530
531	/* Branch to self - 0x100 */
532	instr = create_cond_branch(iptr, addr - 0x100, flags);
533	check(instr_is_branch_to_addr(&instr, addr - 0x100));
534
535	/* Branch to self + 0x100 */
536	instr = create_cond_branch(iptr, addr + 0x100, flags);
537	check(instr_is_branch_to_addr(&instr, addr + 0x100));
538
539	/* Maximum relative negative offset, - 32 KB */
540	instr = create_cond_branch(iptr, addr - 0x8000, flags);
541	check(instr_is_branch_to_addr(&instr, addr - 0x8000));
542
543	/* Out of range relative negative offset, - 32 KB + 4*/
544	instr = create_cond_branch(iptr, addr - 0x8004, flags);
545	check(instr == 0);
546
547	/* Out of range relative positive offset, + 32 KB */
548	instr = create_cond_branch(iptr, addr + 0x8000, flags);
549	check(instr == 0);
550
551	/* Unaligned target */
552	instr = create_cond_branch(iptr, addr + 3, flags);
553	check(instr == 0);
554
555	/* Check flags are masked correctly */
556	instr = create_cond_branch(iptr, addr, 0xFFFFFFFC);
557	check(instr_is_branch_to_addr(&instr, addr));
558	check(instr == 0x43FF0000);
559	}
560
561	static void __init test_translate_branch(void)
562	{
563	unsigned long addr;
564	unsigned int p, q;
565	void *buf;
566
567	buf = vmalloc(PAGE_ALIGN(0x2000000 + 1));
568	check(buf);
569	if (!buf)
570	return;
571
572	/* Simple case, branch to self moved a little */
573	p = buf;
574	addr = (unsigned long)p;
575	patch_branch(p, addr, 0);
576	check(instr_is_branch_to_addr(p, addr));
577	q = p + 1;
578	patch_instruction(q, translate_branch(q, p));
579	check(instr_is_branch_to_addr(q, addr));
580
581	/* Maximum negative case, move b . to addr + 32 MB */
582	p = buf;
583	addr = (unsigned long)p;
584	patch_branch(p, addr, 0);
585	q = buf + 0x2000000;
586	patch_instruction(q, translate_branch(q, p));
587	check(instr_is_branch_to_addr(p, addr));
588	check(instr_is_branch_to_addr(q, addr));
589	check(*q == 0x4a000000);
590
591	/* Maximum positive case, move x to x - 32 MB + 4 */
592	p = buf + 0x2000000;
593	addr = (unsigned long)p;
594	patch_branch(p, addr, 0);
595	q = buf + 4;
596	patch_instruction(q, translate_branch(q, p));
597	check(instr_is_branch_to_addr(p, addr));
598	check(instr_is_branch_to_addr(q, addr));
599	check(*q == 0x49fffffc);
600
601	/* Jump to x + 16 MB moved to x + 20 MB */
602	p = buf;
603	addr = 0x1000000 + (unsigned long)buf;
604	patch_branch(p, addr, BRANCH_SET_LINK);
605	q = buf + 0x1400000;
606	patch_instruction(q, translate_branch(q, p));
607	check(instr_is_branch_to_addr(p, addr));
608	check(instr_is_branch_to_addr(q, addr));
609
610	/* Jump to x + 16 MB moved to x - 16 MB + 4 */
611	p = buf + 0x1000000;
612	addr = 0x2000000 + (unsigned long)buf;
613	patch_branch(p, addr, 0);
614	q = buf + 4;
615	patch_instruction(q, translate_branch(q, p));
616	check(instr_is_branch_to_addr(p, addr));
617	check(instr_is_branch_to_addr(q, addr));
618
619
620	/* Conditional branch tests */
621
622	/* Simple case, branch to self moved a little */
623	p = buf;
624	addr = (unsigned long)p;
625	patch_instruction(p, create_cond_branch(p, addr, 0));
626	check(instr_is_branch_to_addr(p, addr));
627	q = p + 1;
628	patch_instruction(q, translate_branch(q, p));
629	check(instr_is_branch_to_addr(q, addr));
630
631	/* Maximum negative case, move b . to addr + 32 KB */
632	p = buf;
633	addr = (unsigned long)p;
634	patch_instruction(p, create_cond_branch(p, addr, 0xFFFFFFFC));
635	q = buf + 0x8000;
636	patch_instruction(q, translate_branch(q, p));
637	check(instr_is_branch_to_addr(p, addr));
638	check(instr_is_branch_to_addr(q, addr));
639	check(*q == 0x43ff8000);
640
641	/* Maximum positive case, move x to x - 32 KB + 4 */
642	p = buf + 0x8000;
643	addr = (unsigned long)p;
644	patch_instruction(p, create_cond_branch(p, addr, 0xFFFFFFFC));
645	q = buf + 4;
646	patch_instruction(q, translate_branch(q, p));
647	check(instr_is_branch_to_addr(p, addr));
648	check(instr_is_branch_to_addr(q, addr));
649	check(*q == 0x43ff7ffc);
650
651	/* Jump to x + 12 KB moved to x + 20 KB */
652	p = buf;
653	addr = 0x3000 + (unsigned long)buf;
654	patch_instruction(p, create_cond_branch(p, addr, BRANCH_SET_LINK));
655	q = buf + 0x5000;
656	patch_instruction(q, translate_branch(q, p));
657	check(instr_is_branch_to_addr(p, addr));
658	check(instr_is_branch_to_addr(q, addr));
659
660	/* Jump to x + 8 KB moved to x - 8 KB + 4 */
661	p = buf + 0x2000;
662	addr = 0x4000 + (unsigned long)buf;
663	patch_instruction(p, create_cond_branch(p, addr, 0));
664	q = buf + 4;
665	patch_instruction(q, translate_branch(q, p));
666	check(instr_is_branch_to_addr(p, addr));
667	check(instr_is_branch_to_addr(q, addr));
668
669	/* Free the buffer we were using */
670	vfree(buf);
671	}
672
673	static int __init test_code_patching(void)
674	{
675	printk(KERN_DEBUG "Running code patching self-tests ...\n");
676
677	test_branch_iform();
678	test_branch_bform();
679	test_create_function_call();
680	test_translate_branch();
681
682	return 0;
683	}
684	late_initcall(test_code_patching);
685
686	#endif /* CONFIG_CODE_PATCHING_SELFTEST */