594 lines
14 KiB
C
594 lines
14 KiB
C
/*
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* Code for replacing ftrace calls with jumps.
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*
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* Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
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*
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* Thanks goes out to P.A. Semi, Inc for supplying me with a PPC64 box.
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*
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* Added function graph tracer code, taken from x86 that was written
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* by Frederic Weisbecker, and ported to PPC by Steven Rostedt.
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*
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*/
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#include <linux/spinlock.h>
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#include <linux/hardirq.h>
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#include <linux/uaccess.h>
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#include <linux/module.h>
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#include <linux/ftrace.h>
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#include <linux/percpu.h>
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#include <linux/init.h>
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#include <linux/list.h>
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#include <asm/cacheflush.h>
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#include <asm/code-patching.h>
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#include <asm/ftrace.h>
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#include <asm/syscall.h>
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#ifdef CONFIG_DYNAMIC_FTRACE
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static unsigned int
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ftrace_call_replace(unsigned long ip, unsigned long addr, int link)
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{
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unsigned int op;
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addr = ppc_function_entry((void *)addr);
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/* if (link) set op to 'bl' else 'b' */
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op = create_branch((unsigned int *)ip, addr, link ? 1 : 0);
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return op;
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}
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static int
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ftrace_modify_code(unsigned long ip, unsigned int old, unsigned int new)
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{
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unsigned int replaced;
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/*
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* Note: Due to modules and __init, code can
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* disappear and change, we need to protect against faulting
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* as well as code changing. We do this by using the
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* probe_kernel_* functions.
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*
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* No real locking needed, this code is run through
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* kstop_machine, or before SMP starts.
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*/
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/* read the text we want to modify */
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if (probe_kernel_read(&replaced, (void *)ip, MCOUNT_INSN_SIZE))
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return -EFAULT;
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/* Make sure it is what we expect it to be */
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if (replaced != old)
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return -EINVAL;
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/* replace the text with the new text */
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if (patch_instruction((unsigned int *)ip, new))
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return -EPERM;
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return 0;
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}
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/*
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* Helper functions that are the same for both PPC64 and PPC32.
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*/
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static int test_24bit_addr(unsigned long ip, unsigned long addr)
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{
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addr = ppc_function_entry((void *)addr);
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/* use the create_branch to verify that this offset can be branched */
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return create_branch((unsigned int *)ip, addr, 0);
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}
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#ifdef CONFIG_MODULES
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static int is_bl_op(unsigned int op)
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{
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return (op & 0xfc000003) == 0x48000001;
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}
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static unsigned long find_bl_target(unsigned long ip, unsigned int op)
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{
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static int offset;
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offset = (op & 0x03fffffc);
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/* make it signed */
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if (offset & 0x02000000)
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offset |= 0xfe000000;
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return ip + (long)offset;
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}
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#ifdef CONFIG_PPC64
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static int
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__ftrace_make_nop(struct module *mod,
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struct dyn_ftrace *rec, unsigned long addr)
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{
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unsigned int op;
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unsigned long ptr;
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unsigned long ip = rec->ip;
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void *tramp;
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/* read where this goes */
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if (probe_kernel_read(&op, (void *)ip, sizeof(int)))
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return -EFAULT;
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/* Make sure that that this is still a 24bit jump */
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if (!is_bl_op(op)) {
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printk(KERN_ERR "Not expected bl: opcode is %x\n", op);
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return -EINVAL;
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}
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/* lets find where the pointer goes */
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tramp = (void *)find_bl_target(ip, op);
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pr_devel("ip:%lx jumps to %p", ip, tramp);
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if (!is_module_trampoline(tramp)) {
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printk(KERN_ERR "Not a trampoline\n");
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return -EINVAL;
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}
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if (module_trampoline_target(mod, tramp, &ptr)) {
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printk(KERN_ERR "Failed to get trampoline target\n");
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return -EFAULT;
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}
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pr_devel("trampoline target %lx", ptr);
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/* This should match what was called */
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if (ptr != ppc_function_entry((void *)addr)) {
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printk(KERN_ERR "addr %lx does not match expected %lx\n",
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ptr, ppc_function_entry((void *)addr));
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return -EINVAL;
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}
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/*
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* Our original call site looks like:
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*
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* bl <tramp>
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* ld r2,XX(r1)
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*
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* Milton Miller pointed out that we can not simply nop the branch.
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* If a task was preempted when calling a trace function, the nops
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* will remove the way to restore the TOC in r2 and the r2 TOC will
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* get corrupted.
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*
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* Use a b +8 to jump over the load.
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*/
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op = 0x48000008; /* b +8 */
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if (patch_instruction((unsigned int *)ip, op))
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return -EPERM;
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return 0;
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}
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#else /* !PPC64 */
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static int
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__ftrace_make_nop(struct module *mod,
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struct dyn_ftrace *rec, unsigned long addr)
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{
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unsigned int op;
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unsigned int jmp[4];
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unsigned long ip = rec->ip;
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unsigned long tramp;
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if (probe_kernel_read(&op, (void *)ip, MCOUNT_INSN_SIZE))
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return -EFAULT;
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/* Make sure that that this is still a 24bit jump */
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if (!is_bl_op(op)) {
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printk(KERN_ERR "Not expected bl: opcode is %x\n", op);
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return -EINVAL;
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}
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/* lets find where the pointer goes */
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tramp = find_bl_target(ip, op);
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/*
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* On PPC32 the trampoline looks like:
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* 0x3d, 0x80, 0x00, 0x00 lis r12,sym@ha
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* 0x39, 0x8c, 0x00, 0x00 addi r12,r12,sym@l
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* 0x7d, 0x89, 0x03, 0xa6 mtctr r12
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* 0x4e, 0x80, 0x04, 0x20 bctr
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*/
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pr_devel("ip:%lx jumps to %lx", ip, tramp);
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/* Find where the trampoline jumps to */
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if (probe_kernel_read(jmp, (void *)tramp, sizeof(jmp))) {
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printk(KERN_ERR "Failed to read %lx\n", tramp);
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return -EFAULT;
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}
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pr_devel(" %08x %08x ", jmp[0], jmp[1]);
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/* verify that this is what we expect it to be */
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if (((jmp[0] & 0xffff0000) != 0x3d800000) ||
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((jmp[1] & 0xffff0000) != 0x398c0000) ||
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(jmp[2] != 0x7d8903a6) ||
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(jmp[3] != 0x4e800420)) {
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printk(KERN_ERR "Not a trampoline\n");
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return -EINVAL;
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}
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tramp = (jmp[1] & 0xffff) |
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((jmp[0] & 0xffff) << 16);
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if (tramp & 0x8000)
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tramp -= 0x10000;
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pr_devel(" %lx ", tramp);
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if (tramp != addr) {
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printk(KERN_ERR
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"Trampoline location %08lx does not match addr\n",
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tramp);
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return -EINVAL;
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}
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op = PPC_INST_NOP;
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if (patch_instruction((unsigned int *)ip, op))
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return -EPERM;
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return 0;
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}
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#endif /* PPC64 */
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#endif /* CONFIG_MODULES */
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int ftrace_make_nop(struct module *mod,
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struct dyn_ftrace *rec, unsigned long addr)
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{
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unsigned long ip = rec->ip;
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unsigned int old, new;
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/*
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* If the calling address is more that 24 bits away,
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* then we had to use a trampoline to make the call.
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* Otherwise just update the call site.
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*/
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if (test_24bit_addr(ip, addr)) {
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/* within range */
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old = ftrace_call_replace(ip, addr, 1);
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new = PPC_INST_NOP;
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return ftrace_modify_code(ip, old, new);
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}
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#ifdef CONFIG_MODULES
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/*
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* Out of range jumps are called from modules.
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* We should either already have a pointer to the module
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* or it has been passed in.
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*/
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if (!rec->arch.mod) {
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if (!mod) {
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printk(KERN_ERR "No module loaded addr=%lx\n",
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addr);
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return -EFAULT;
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}
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rec->arch.mod = mod;
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} else if (mod) {
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if (mod != rec->arch.mod) {
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printk(KERN_ERR
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"Record mod %p not equal to passed in mod %p\n",
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rec->arch.mod, mod);
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return -EINVAL;
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}
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/* nothing to do if mod == rec->arch.mod */
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} else
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mod = rec->arch.mod;
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return __ftrace_make_nop(mod, rec, addr);
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#else
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/* We should not get here without modules */
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return -EINVAL;
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#endif /* CONFIG_MODULES */
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}
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#ifdef CONFIG_MODULES
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#ifdef CONFIG_PPC64
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static int
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__ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
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{
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unsigned int op[2];
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void *ip = (void *)rec->ip;
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/* read where this goes */
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if (probe_kernel_read(op, ip, sizeof(op)))
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return -EFAULT;
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/*
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* We expect to see:
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*
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* b +8
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* ld r2,XX(r1)
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*
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* The load offset is different depending on the ABI. For simplicity
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* just mask it out when doing the compare.
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*/
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if ((op[0] != 0x48000008) || ((op[1] & 0xffff00000) != 0xe8410000)) {
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printk(KERN_ERR "Unexpected call sequence: %x %x\n",
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op[0], op[1]);
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return -EINVAL;
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}
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/* If we never set up a trampoline to ftrace_caller, then bail */
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if (!rec->arch.mod->arch.tramp) {
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printk(KERN_ERR "No ftrace trampoline\n");
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return -EINVAL;
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}
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/* Ensure branch is within 24 bits */
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if (create_branch(ip, rec->arch.mod->arch.tramp, BRANCH_SET_LINK)) {
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printk(KERN_ERR "Branch out of range");
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return -EINVAL;
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}
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if (patch_branch(ip, rec->arch.mod->arch.tramp, BRANCH_SET_LINK)) {
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printk(KERN_ERR "REL24 out of range!\n");
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return -EINVAL;
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}
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return 0;
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}
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#else
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static int
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__ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
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{
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unsigned int op;
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unsigned long ip = rec->ip;
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/* read where this goes */
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if (probe_kernel_read(&op, (void *)ip, MCOUNT_INSN_SIZE))
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return -EFAULT;
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/* It should be pointing to a nop */
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if (op != PPC_INST_NOP) {
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printk(KERN_ERR "Expected NOP but have %x\n", op);
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return -EINVAL;
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}
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/* If we never set up a trampoline to ftrace_caller, then bail */
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if (!rec->arch.mod->arch.tramp) {
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printk(KERN_ERR "No ftrace trampoline\n");
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return -EINVAL;
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}
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/* create the branch to the trampoline */
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op = create_branch((unsigned int *)ip,
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rec->arch.mod->arch.tramp, BRANCH_SET_LINK);
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if (!op) {
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printk(KERN_ERR "REL24 out of range!\n");
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return -EINVAL;
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}
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pr_devel("write to %lx\n", rec->ip);
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if (patch_instruction((unsigned int *)ip, op))
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return -EPERM;
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return 0;
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}
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#endif /* CONFIG_PPC64 */
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#endif /* CONFIG_MODULES */
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int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
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{
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unsigned long ip = rec->ip;
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unsigned int old, new;
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/*
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* If the calling address is more that 24 bits away,
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* then we had to use a trampoline to make the call.
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* Otherwise just update the call site.
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*/
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if (test_24bit_addr(ip, addr)) {
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/* within range */
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old = PPC_INST_NOP;
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new = ftrace_call_replace(ip, addr, 1);
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return ftrace_modify_code(ip, old, new);
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}
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#ifdef CONFIG_MODULES
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/*
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* Out of range jumps are called from modules.
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* Being that we are converting from nop, it had better
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* already have a module defined.
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*/
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if (!rec->arch.mod) {
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printk(KERN_ERR "No module loaded\n");
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return -EINVAL;
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}
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return __ftrace_make_call(rec, addr);
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#else
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/* We should not get here without modules */
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return -EINVAL;
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#endif /* CONFIG_MODULES */
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}
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int ftrace_update_ftrace_func(ftrace_func_t func)
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{
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unsigned long ip = (unsigned long)(&ftrace_call);
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unsigned int old, new;
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int ret;
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old = *(unsigned int *)&ftrace_call;
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new = ftrace_call_replace(ip, (unsigned long)func, 1);
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ret = ftrace_modify_code(ip, old, new);
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return ret;
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}
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static int __ftrace_replace_code(struct dyn_ftrace *rec, int enable)
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{
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unsigned long ftrace_addr = (unsigned long)FTRACE_ADDR;
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int ret;
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ret = ftrace_update_record(rec, enable);
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switch (ret) {
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case FTRACE_UPDATE_IGNORE:
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return 0;
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case FTRACE_UPDATE_MAKE_CALL:
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return ftrace_make_call(rec, ftrace_addr);
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case FTRACE_UPDATE_MAKE_NOP:
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return ftrace_make_nop(NULL, rec, ftrace_addr);
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}
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return 0;
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}
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void ftrace_replace_code(int enable)
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{
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struct ftrace_rec_iter *iter;
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struct dyn_ftrace *rec;
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int ret;
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for (iter = ftrace_rec_iter_start(); iter;
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iter = ftrace_rec_iter_next(iter)) {
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rec = ftrace_rec_iter_record(iter);
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ret = __ftrace_replace_code(rec, enable);
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if (ret) {
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ftrace_bug(ret, rec->ip);
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return;
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}
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}
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}
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void arch_ftrace_update_code(int command)
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{
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if (command & FTRACE_UPDATE_CALLS)
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ftrace_replace_code(1);
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else if (command & FTRACE_DISABLE_CALLS)
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ftrace_replace_code(0);
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if (command & FTRACE_UPDATE_TRACE_FUNC)
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ftrace_update_ftrace_func(ftrace_trace_function);
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if (command & FTRACE_START_FUNC_RET)
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ftrace_enable_ftrace_graph_caller();
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else if (command & FTRACE_STOP_FUNC_RET)
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ftrace_disable_ftrace_graph_caller();
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}
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int __init ftrace_dyn_arch_init(void)
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{
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return 0;
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}
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#endif /* CONFIG_DYNAMIC_FTRACE */
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER
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#ifdef CONFIG_DYNAMIC_FTRACE
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extern void ftrace_graph_call(void);
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extern void ftrace_graph_stub(void);
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int ftrace_enable_ftrace_graph_caller(void)
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{
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unsigned long ip = (unsigned long)(&ftrace_graph_call);
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unsigned long addr = (unsigned long)(&ftrace_graph_caller);
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unsigned long stub = (unsigned long)(&ftrace_graph_stub);
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unsigned int old, new;
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old = ftrace_call_replace(ip, stub, 0);
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new = ftrace_call_replace(ip, addr, 0);
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return ftrace_modify_code(ip, old, new);
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}
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int ftrace_disable_ftrace_graph_caller(void)
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{
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unsigned long ip = (unsigned long)(&ftrace_graph_call);
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unsigned long addr = (unsigned long)(&ftrace_graph_caller);
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unsigned long stub = (unsigned long)(&ftrace_graph_stub);
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unsigned int old, new;
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old = ftrace_call_replace(ip, addr, 0);
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new = ftrace_call_replace(ip, stub, 0);
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return ftrace_modify_code(ip, old, new);
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}
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#endif /* CONFIG_DYNAMIC_FTRACE */
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#ifdef CONFIG_PPC64
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extern void mod_return_to_handler(void);
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#endif
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/*
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* Hook the return address and push it in the stack of return addrs
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* in current thread info.
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*/
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void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr)
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{
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unsigned long old;
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int faulted;
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struct ftrace_graph_ent trace;
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unsigned long return_hooker = (unsigned long)&return_to_handler;
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if (unlikely(atomic_read(¤t->tracing_graph_pause)))
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return;
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#ifdef CONFIG_PPC64
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/* non core kernel code needs to save and restore the TOC */
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if (REGION_ID(self_addr) != KERNEL_REGION_ID)
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return_hooker = (unsigned long)&mod_return_to_handler;
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#endif
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return_hooker = ppc_function_entry((void *)return_hooker);
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/*
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* Protect against fault, even if it shouldn't
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* happen. This tool is too much intrusive to
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* ignore such a protection.
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*/
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asm volatile(
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"1: " PPC_LL "%[old], 0(%[parent])\n"
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"2: " PPC_STL "%[return_hooker], 0(%[parent])\n"
|
|
" li %[faulted], 0\n"
|
|
"3:\n"
|
|
|
|
".section .fixup, \"ax\"\n"
|
|
"4: li %[faulted], 1\n"
|
|
" b 3b\n"
|
|
".previous\n"
|
|
|
|
".section __ex_table,\"a\"\n"
|
|
PPC_LONG_ALIGN "\n"
|
|
PPC_LONG "1b,4b\n"
|
|
PPC_LONG "2b,4b\n"
|
|
".previous"
|
|
|
|
: [old] "=&r" (old), [faulted] "=r" (faulted)
|
|
: [parent] "r" (parent), [return_hooker] "r" (return_hooker)
|
|
: "memory"
|
|
);
|
|
|
|
if (unlikely(faulted)) {
|
|
ftrace_graph_stop();
|
|
WARN_ON(1);
|
|
return;
|
|
}
|
|
|
|
trace.func = self_addr;
|
|
trace.depth = current->curr_ret_stack + 1;
|
|
|
|
/* Only trace if the calling function expects to */
|
|
if (!ftrace_graph_entry(&trace)) {
|
|
*parent = old;
|
|
return;
|
|
}
|
|
|
|
if (ftrace_push_return_trace(old, self_addr, &trace.depth, 0) == -EBUSY)
|
|
*parent = old;
|
|
}
|
|
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
|
|
|
|
#if defined(CONFIG_FTRACE_SYSCALLS) && defined(CONFIG_PPC64)
|
|
unsigned long __init arch_syscall_addr(int nr)
|
|
{
|
|
return sys_call_table[nr*2];
|
|
}
|
|
#endif /* CONFIG_FTRACE_SYSCALLS && CONFIG_PPC64 */
|