| Author | Tokens | Token Proportion | Commits | Commit Proportion |
|---|---|---|---|---|
| Michael Ellerman | 2186 | 72.03% | 5 | 25.00% |
| Balbir Singh | 545 | 17.96% | 1 | 5.00% |
| Anju T | 98 | 3.23% | 2 | 10.00% |
| Christophe Leroy | 94 | 3.10% | 3 | 15.00% |
| Kevin Hao | 48 | 1.58% | 1 | 5.00% |
| Steven Rostedt | 22 | 0.72% | 1 | 5.00% |
| Josh Poimboeuf | 21 | 0.69% | 1 | 5.00% |
| Naveen N. Rao | 8 | 0.26% | 1 | 5.00% |
| Russell Currey | 5 | 0.16% | 1 | 5.00% |
| Andrea Righi | 3 | 0.10% | 1 | 5.00% |
| Thomas Gleixner | 2 | 0.07% | 1 | 5.00% |
| Benjamin Herrenschmidt | 2 | 0.07% | 1 | 5.00% |
| Linus Torvalds | 1 | 0.03% | 1 | 5.00% |
| Total | 3035 | 20 |
// 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 */
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