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45090c2661
Using patch_site_addr() helper, patch_instruction_site() and patch_branch_site() can be simplified and inlined. Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
692 lines
18 KiB
C
692 lines
18 KiB
C
/*
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* Copyright 2008 Michael Ellerman, IBM Corporation.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <linux/kernel.h>
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#include <linux/kprobes.h>
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#include <linux/vmalloc.h>
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#include <linux/init.h>
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#include <linux/mm.h>
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#include <linux/cpuhotplug.h>
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#include <linux/slab.h>
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#include <linux/uaccess.h>
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#include <linux/kprobes.h>
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#include <asm/pgtable.h>
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#include <asm/tlbflush.h>
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#include <asm/page.h>
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#include <asm/code-patching.h>
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#include <asm/setup.h>
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static int __patch_instruction(unsigned int *exec_addr, unsigned int instr,
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unsigned int *patch_addr)
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{
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int err;
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__put_user_size(instr, patch_addr, 4, err);
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if (err)
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return err;
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asm ("dcbst 0, %0; sync; icbi 0,%1; sync; isync" :: "r" (patch_addr),
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"r" (exec_addr));
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return 0;
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}
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int raw_patch_instruction(unsigned int *addr, unsigned int instr)
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{
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return __patch_instruction(addr, instr, addr);
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}
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#ifdef CONFIG_STRICT_KERNEL_RWX
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static DEFINE_PER_CPU(struct vm_struct *, text_poke_area);
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static int text_area_cpu_up(unsigned int cpu)
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{
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struct vm_struct *area;
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area = get_vm_area(PAGE_SIZE, VM_ALLOC);
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if (!area) {
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WARN_ONCE(1, "Failed to create text area for cpu %d\n",
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cpu);
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return -1;
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}
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this_cpu_write(text_poke_area, area);
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return 0;
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}
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static int text_area_cpu_down(unsigned int cpu)
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{
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free_vm_area(this_cpu_read(text_poke_area));
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return 0;
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}
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/*
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* Run as a late init call. This allows all the boot time patching to be done
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* simply by patching the code, and then we're called here prior to
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* mark_rodata_ro(), which happens after all init calls are run. Although
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* BUG_ON() is rude, in this case it should only happen if ENOMEM, and we judge
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* it as being preferable to a kernel that will crash later when someone tries
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* to use patch_instruction().
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*/
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static int __init setup_text_poke_area(void)
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{
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BUG_ON(!cpuhp_setup_state(CPUHP_AP_ONLINE_DYN,
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"powerpc/text_poke:online", text_area_cpu_up,
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text_area_cpu_down));
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return 0;
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}
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late_initcall(setup_text_poke_area);
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/*
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* This can be called for kernel text or a module.
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*/
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static int map_patch_area(void *addr, unsigned long text_poke_addr)
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{
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unsigned long pfn;
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int err;
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if (is_vmalloc_addr(addr))
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pfn = vmalloc_to_pfn(addr);
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else
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pfn = __pa_symbol(addr) >> PAGE_SHIFT;
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err = map_kernel_page(text_poke_addr, (pfn << PAGE_SHIFT), PAGE_KERNEL);
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pr_devel("Mapped addr %lx with pfn %lx:%d\n", text_poke_addr, pfn, err);
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if (err)
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return -1;
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return 0;
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}
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static inline int unmap_patch_area(unsigned long addr)
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{
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pte_t *ptep;
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pmd_t *pmdp;
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pud_t *pudp;
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pgd_t *pgdp;
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pgdp = pgd_offset_k(addr);
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if (unlikely(!pgdp))
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return -EINVAL;
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pudp = pud_offset(pgdp, addr);
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if (unlikely(!pudp))
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return -EINVAL;
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pmdp = pmd_offset(pudp, addr);
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if (unlikely(!pmdp))
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return -EINVAL;
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ptep = pte_offset_kernel(pmdp, addr);
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if (unlikely(!ptep))
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return -EINVAL;
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pr_devel("clearing mm %p, pte %p, addr %lx\n", &init_mm, ptep, addr);
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/*
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* In hash, pte_clear flushes the tlb, in radix, we have to
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*/
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pte_clear(&init_mm, addr, ptep);
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flush_tlb_kernel_range(addr, addr + PAGE_SIZE);
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return 0;
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}
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static int do_patch_instruction(unsigned int *addr, unsigned int instr)
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{
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int err;
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unsigned int *patch_addr = NULL;
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unsigned long flags;
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unsigned long text_poke_addr;
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unsigned long kaddr = (unsigned long)addr;
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/*
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* During early early boot patch_instruction is called
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* when text_poke_area is not ready, but we still need
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* to allow patching. We just do the plain old patching
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*/
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if (!this_cpu_read(text_poke_area))
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return raw_patch_instruction(addr, instr);
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local_irq_save(flags);
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text_poke_addr = (unsigned long)__this_cpu_read(text_poke_area)->addr;
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if (map_patch_area(addr, text_poke_addr)) {
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err = -1;
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goto out;
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}
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patch_addr = (unsigned int *)(text_poke_addr) +
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((kaddr & ~PAGE_MASK) / sizeof(unsigned int));
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__patch_instruction(addr, instr, patch_addr);
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err = unmap_patch_area(text_poke_addr);
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if (err)
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pr_warn("failed to unmap %lx\n", text_poke_addr);
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out:
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local_irq_restore(flags);
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return err;
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}
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#else /* !CONFIG_STRICT_KERNEL_RWX */
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static int do_patch_instruction(unsigned int *addr, unsigned int instr)
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{
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return raw_patch_instruction(addr, instr);
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}
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#endif /* CONFIG_STRICT_KERNEL_RWX */
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int patch_instruction(unsigned int *addr, unsigned int instr)
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{
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/* Make sure we aren't patching a freed init section */
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if (init_mem_is_free && init_section_contains(addr, 4)) {
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pr_debug("Skipping init section patching addr: 0x%px\n", addr);
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return 0;
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}
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return do_patch_instruction(addr, instr);
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}
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NOKPROBE_SYMBOL(patch_instruction);
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int patch_branch(unsigned int *addr, unsigned long target, int flags)
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{
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return patch_instruction(addr, create_branch(addr, target, flags));
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}
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bool is_offset_in_branch_range(long offset)
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{
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/*
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* Powerpc branch instruction is :
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*
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* 0 6 30 31
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* +---------+----------------+---+---+
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* | opcode | LI |AA |LK |
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* +---------+----------------+---+---+
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* Where AA = 0 and LK = 0
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*
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* LI is a signed 24 bits integer. The real branch offset is computed
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* by: imm32 = SignExtend(LI:'0b00', 32);
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*
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* So the maximum forward branch should be:
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* (0x007fffff << 2) = 0x01fffffc = 0x1fffffc
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* The maximum backward branch should be:
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* (0xff800000 << 2) = 0xfe000000 = -0x2000000
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*/
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return (offset >= -0x2000000 && offset <= 0x1fffffc && !(offset & 0x3));
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}
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/*
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* Helper to check if a given instruction is a conditional branch
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* Derived from the conditional checks in analyse_instr()
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*/
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bool is_conditional_branch(unsigned int instr)
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{
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unsigned int opcode = instr >> 26;
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if (opcode == 16) /* bc, bca, bcl, bcla */
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return true;
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if (opcode == 19) {
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switch ((instr >> 1) & 0x3ff) {
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case 16: /* bclr, bclrl */
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case 528: /* bcctr, bcctrl */
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case 560: /* bctar, bctarl */
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return true;
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}
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}
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return false;
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}
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NOKPROBE_SYMBOL(is_conditional_branch);
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unsigned int create_branch(const unsigned int *addr,
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unsigned long target, int flags)
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{
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unsigned int instruction;
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long offset;
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offset = target;
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if (! (flags & BRANCH_ABSOLUTE))
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offset = offset - (unsigned long)addr;
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/* Check we can represent the target in the instruction format */
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if (!is_offset_in_branch_range(offset))
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return 0;
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/* Mask out the flags and target, so they don't step on each other. */
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instruction = 0x48000000 | (flags & 0x3) | (offset & 0x03FFFFFC);
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return instruction;
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}
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unsigned int create_cond_branch(const unsigned int *addr,
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unsigned long target, int flags)
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{
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unsigned int instruction;
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long offset;
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offset = target;
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if (! (flags & BRANCH_ABSOLUTE))
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offset = offset - (unsigned long)addr;
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/* Check we can represent the target in the instruction format */
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if (offset < -0x8000 || offset > 0x7FFF || offset & 0x3)
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return 0;
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/* Mask out the flags and target, so they don't step on each other. */
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instruction = 0x40000000 | (flags & 0x3FF0003) | (offset & 0xFFFC);
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return instruction;
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}
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static unsigned int branch_opcode(unsigned int instr)
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{
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return (instr >> 26) & 0x3F;
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}
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static int instr_is_branch_iform(unsigned int instr)
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{
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return branch_opcode(instr) == 18;
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}
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static int instr_is_branch_bform(unsigned int instr)
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{
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return branch_opcode(instr) == 16;
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}
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int instr_is_relative_branch(unsigned int instr)
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{
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if (instr & BRANCH_ABSOLUTE)
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return 0;
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return instr_is_branch_iform(instr) || instr_is_branch_bform(instr);
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}
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int instr_is_relative_link_branch(unsigned int instr)
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{
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return instr_is_relative_branch(instr) && (instr & BRANCH_SET_LINK);
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}
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static unsigned long branch_iform_target(const unsigned int *instr)
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{
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signed long imm;
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imm = *instr & 0x3FFFFFC;
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/* If the top bit of the immediate value is set this is negative */
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if (imm & 0x2000000)
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imm -= 0x4000000;
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if ((*instr & BRANCH_ABSOLUTE) == 0)
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imm += (unsigned long)instr;
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return (unsigned long)imm;
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}
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static unsigned long branch_bform_target(const unsigned int *instr)
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{
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signed long imm;
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imm = *instr & 0xFFFC;
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/* If the top bit of the immediate value is set this is negative */
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if (imm & 0x8000)
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imm -= 0x10000;
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if ((*instr & BRANCH_ABSOLUTE) == 0)
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imm += (unsigned long)instr;
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return (unsigned long)imm;
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}
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unsigned long branch_target(const unsigned int *instr)
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{
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if (instr_is_branch_iform(*instr))
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return branch_iform_target(instr);
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else if (instr_is_branch_bform(*instr))
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return branch_bform_target(instr);
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return 0;
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}
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int instr_is_branch_to_addr(const unsigned int *instr, unsigned long addr)
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{
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if (instr_is_branch_iform(*instr) || instr_is_branch_bform(*instr))
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return branch_target(instr) == addr;
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return 0;
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}
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unsigned int translate_branch(const unsigned int *dest, const unsigned int *src)
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{
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unsigned long target;
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target = branch_target(src);
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if (instr_is_branch_iform(*src))
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return create_branch(dest, target, *src);
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else if (instr_is_branch_bform(*src))
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return create_cond_branch(dest, target, *src);
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return 0;
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}
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#ifdef CONFIG_PPC_BOOK3E_64
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void __patch_exception(int exc, unsigned long addr)
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{
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extern unsigned int interrupt_base_book3e;
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unsigned int *ibase = &interrupt_base_book3e;
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/* Our exceptions vectors start with a NOP and -then- a branch
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* to deal with single stepping from userspace which stops on
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* the second instruction. Thus we need to patch the second
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* instruction of the exception, not the first one
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*/
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patch_branch(ibase + (exc / 4) + 1, addr, 0);
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}
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#endif
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#ifdef CONFIG_CODE_PATCHING_SELFTEST
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static void __init test_trampoline(void)
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{
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asm ("nop;\n");
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}
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#define check(x) \
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if (!(x)) printk("code-patching: test failed at line %d\n", __LINE__);
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static void __init test_branch_iform(void)
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{
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unsigned int instr;
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unsigned long addr;
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addr = (unsigned long)&instr;
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/* The simplest case, branch to self, no flags */
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check(instr_is_branch_iform(0x48000000));
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/* All bits of target set, and flags */
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check(instr_is_branch_iform(0x4bffffff));
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/* High bit of opcode set, which is wrong */
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check(!instr_is_branch_iform(0xcbffffff));
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/* Middle bits of opcode set, which is wrong */
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check(!instr_is_branch_iform(0x7bffffff));
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/* Simplest case, branch to self with link */
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check(instr_is_branch_iform(0x48000001));
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/* All bits of targets set */
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check(instr_is_branch_iform(0x4bfffffd));
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/* Some bits of targets set */
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check(instr_is_branch_iform(0x4bff00fd));
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/* Must be a valid branch to start with */
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check(!instr_is_branch_iform(0x7bfffffd));
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/* Absolute branch to 0x100 */
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instr = 0x48000103;
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check(instr_is_branch_to_addr(&instr, 0x100));
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/* Absolute branch to 0x420fc */
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instr = 0x480420ff;
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check(instr_is_branch_to_addr(&instr, 0x420fc));
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/* Maximum positive relative branch, + 20MB - 4B */
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instr = 0x49fffffc;
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check(instr_is_branch_to_addr(&instr, addr + 0x1FFFFFC));
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/* Smallest negative relative branch, - 4B */
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instr = 0x4bfffffc;
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check(instr_is_branch_to_addr(&instr, addr - 4));
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/* Largest negative relative branch, - 32 MB */
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instr = 0x4a000000;
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check(instr_is_branch_to_addr(&instr, addr - 0x2000000));
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/* Branch to self, with link */
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instr = create_branch(&instr, addr, BRANCH_SET_LINK);
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check(instr_is_branch_to_addr(&instr, addr));
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/* Branch to self - 0x100, with link */
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instr = create_branch(&instr, addr - 0x100, BRANCH_SET_LINK);
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check(instr_is_branch_to_addr(&instr, addr - 0x100));
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/* Branch to self + 0x100, no link */
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instr = create_branch(&instr, addr + 0x100, 0);
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check(instr_is_branch_to_addr(&instr, addr + 0x100));
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/* Maximum relative negative offset, - 32 MB */
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instr = create_branch(&instr, addr - 0x2000000, BRANCH_SET_LINK);
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check(instr_is_branch_to_addr(&instr, addr - 0x2000000));
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/* Out of range relative negative offset, - 32 MB + 4*/
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instr = create_branch(&instr, addr - 0x2000004, BRANCH_SET_LINK);
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check(instr == 0);
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/* Out of range relative positive offset, + 32 MB */
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instr = create_branch(&instr, addr + 0x2000000, BRANCH_SET_LINK);
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check(instr == 0);
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/* Unaligned target */
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instr = create_branch(&instr, addr + 3, BRANCH_SET_LINK);
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check(instr == 0);
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/* Check flags are masked correctly */
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instr = create_branch(&instr, addr, 0xFFFFFFFC);
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check(instr_is_branch_to_addr(&instr, addr));
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check(instr == 0x48000000);
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}
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static void __init test_create_function_call(void)
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{
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unsigned int *iptr;
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unsigned long dest;
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/* Check we can create a function call */
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iptr = (unsigned int *)ppc_function_entry(test_trampoline);
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dest = ppc_function_entry(test_create_function_call);
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patch_instruction(iptr, create_branch(iptr, dest, BRANCH_SET_LINK));
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check(instr_is_branch_to_addr(iptr, dest));
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}
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static void __init test_branch_bform(void)
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{
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unsigned long addr;
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unsigned int *iptr, instr, flags;
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iptr = &instr;
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addr = (unsigned long)iptr;
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/* The simplest case, branch to self, no flags */
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check(instr_is_branch_bform(0x40000000));
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/* All bits of target set, and flags */
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check(instr_is_branch_bform(0x43ffffff));
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/* High bit of opcode set, which is wrong */
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check(!instr_is_branch_bform(0xc3ffffff));
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/* Middle bits of opcode set, which is wrong */
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check(!instr_is_branch_bform(0x7bffffff));
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/* Absolute conditional branch to 0x100 */
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instr = 0x43ff0103;
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check(instr_is_branch_to_addr(&instr, 0x100));
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/* Absolute conditional branch to 0x20fc */
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instr = 0x43ff20ff;
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check(instr_is_branch_to_addr(&instr, 0x20fc));
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/* Maximum positive relative conditional branch, + 32 KB - 4B */
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instr = 0x43ff7ffc;
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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 */
|