620 lines
14 KiB
C
620 lines
14 KiB
C
/*
|
|
* Code for replacing ftrace calls with jumps.
|
|
*
|
|
* Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
|
|
*
|
|
* Thanks goes out to P.A. Semi, Inc for supplying me with a PPC64 box.
|
|
*
|
|
* Added function graph tracer code, taken from x86 that was written
|
|
* by Frederic Weisbecker, and ported to PPC by Steven Rostedt.
|
|
*
|
|
*/
|
|
|
|
#define pr_fmt(fmt) "ftrace-powerpc: " fmt
|
|
|
|
#include <linux/spinlock.h>
|
|
#include <linux/hardirq.h>
|
|
#include <linux/uaccess.h>
|
|
#include <linux/module.h>
|
|
#include <linux/ftrace.h>
|
|
#include <linux/percpu.h>
|
|
#include <linux/init.h>
|
|
#include <linux/list.h>
|
|
|
|
#include <asm/cacheflush.h>
|
|
#include <asm/code-patching.h>
|
|
#include <asm/ftrace.h>
|
|
#include <asm/syscall.h>
|
|
|
|
|
|
#ifdef CONFIG_DYNAMIC_FTRACE
|
|
static unsigned int
|
|
ftrace_call_replace(unsigned long ip, unsigned long addr, int link)
|
|
{
|
|
unsigned int op;
|
|
|
|
addr = ppc_function_entry((void *)addr);
|
|
|
|
/* if (link) set op to 'bl' else 'b' */
|
|
op = create_branch((unsigned int *)ip, addr, link ? 1 : 0);
|
|
|
|
return op;
|
|
}
|
|
|
|
static int
|
|
ftrace_modify_code(unsigned long ip, unsigned int old, unsigned int new)
|
|
{
|
|
unsigned int replaced;
|
|
|
|
/*
|
|
* Note:
|
|
* We are paranoid about modifying text, as if a bug was to happen, it
|
|
* could cause us to read or write to someplace that could cause harm.
|
|
* Carefully read and modify the code with probe_kernel_*(), and make
|
|
* sure what we read is what we expected it to be before modifying it.
|
|
*/
|
|
|
|
/* read the text we want to modify */
|
|
if (probe_kernel_read(&replaced, (void *)ip, MCOUNT_INSN_SIZE))
|
|
return -EFAULT;
|
|
|
|
/* Make sure it is what we expect it to be */
|
|
if (replaced != old) {
|
|
pr_err("%p: replaced (%#x) != old (%#x)",
|
|
(void *)ip, replaced, old);
|
|
return -EINVAL;
|
|
}
|
|
|
|
/* replace the text with the new text */
|
|
if (patch_instruction((unsigned int *)ip, new))
|
|
return -EPERM;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Helper functions that are the same for both PPC64 and PPC32.
|
|
*/
|
|
static int test_24bit_addr(unsigned long ip, unsigned long addr)
|
|
{
|
|
addr = ppc_function_entry((void *)addr);
|
|
|
|
/* use the create_branch to verify that this offset can be branched */
|
|
return create_branch((unsigned int *)ip, addr, 0);
|
|
}
|
|
|
|
#ifdef CONFIG_MODULES
|
|
|
|
static int is_bl_op(unsigned int op)
|
|
{
|
|
return (op & 0xfc000003) == 0x48000001;
|
|
}
|
|
|
|
static unsigned long find_bl_target(unsigned long ip, unsigned int op)
|
|
{
|
|
static int offset;
|
|
|
|
offset = (op & 0x03fffffc);
|
|
/* make it signed */
|
|
if (offset & 0x02000000)
|
|
offset |= 0xfe000000;
|
|
|
|
return ip + (long)offset;
|
|
}
|
|
|
|
#ifdef CONFIG_PPC64
|
|
static int
|
|
__ftrace_make_nop(struct module *mod,
|
|
struct dyn_ftrace *rec, unsigned long addr)
|
|
{
|
|
unsigned long entry, ptr, tramp;
|
|
unsigned long ip = rec->ip;
|
|
unsigned int op, pop;
|
|
|
|
/* read where this goes */
|
|
if (probe_kernel_read(&op, (void *)ip, sizeof(int))) {
|
|
pr_err("Fetching opcode failed.\n");
|
|
return -EFAULT;
|
|
}
|
|
|
|
/* Make sure that that this is still a 24bit jump */
|
|
if (!is_bl_op(op)) {
|
|
pr_err("Not expected bl: opcode is %x\n", op);
|
|
return -EINVAL;
|
|
}
|
|
|
|
/* lets find where the pointer goes */
|
|
tramp = find_bl_target(ip, op);
|
|
|
|
pr_devel("ip:%lx jumps to %lx", ip, tramp);
|
|
|
|
if (module_trampoline_target(mod, tramp, &ptr)) {
|
|
pr_err("Failed to get trampoline target\n");
|
|
return -EFAULT;
|
|
}
|
|
|
|
pr_devel("trampoline target %lx", ptr);
|
|
|
|
entry = ppc_global_function_entry((void *)addr);
|
|
/* This should match what was called */
|
|
if (ptr != entry) {
|
|
pr_err("addr %lx does not match expected %lx\n", ptr, entry);
|
|
return -EINVAL;
|
|
}
|
|
|
|
#ifdef CC_USING_MPROFILE_KERNEL
|
|
/* When using -mkernel_profile there is no load to jump over */
|
|
pop = PPC_INST_NOP;
|
|
|
|
if (probe_kernel_read(&op, (void *)(ip - 4), 4)) {
|
|
pr_err("Fetching instruction at %lx failed.\n", ip - 4);
|
|
return -EFAULT;
|
|
}
|
|
|
|
/* We expect either a mflr r0, or a std r0, LRSAVE(r1) */
|
|
if (op != PPC_INST_MFLR && op != PPC_INST_STD_LR) {
|
|
pr_err("Unexpected instruction %08x around bl _mcount\n", op);
|
|
return -EINVAL;
|
|
}
|
|
#else
|
|
/*
|
|
* Our original call site looks like:
|
|
*
|
|
* bl <tramp>
|
|
* ld r2,XX(r1)
|
|
*
|
|
* Milton Miller pointed out that we can not simply nop the branch.
|
|
* If a task was preempted when calling a trace function, the nops
|
|
* will remove the way to restore the TOC in r2 and the r2 TOC will
|
|
* get corrupted.
|
|
*
|
|
* Use a b +8 to jump over the load.
|
|
*/
|
|
|
|
pop = PPC_INST_BRANCH | 8; /* b +8 */
|
|
|
|
/*
|
|
* Check what is in the next instruction. We can see ld r2,40(r1), but
|
|
* on first pass after boot we will see mflr r0.
|
|
*/
|
|
if (probe_kernel_read(&op, (void *)(ip+4), MCOUNT_INSN_SIZE)) {
|
|
pr_err("Fetching op failed.\n");
|
|
return -EFAULT;
|
|
}
|
|
|
|
if (op != PPC_INST_LD_TOC) {
|
|
pr_err("Expected %08x found %08x\n", PPC_INST_LD_TOC, op);
|
|
return -EINVAL;
|
|
}
|
|
#endif /* CC_USING_MPROFILE_KERNEL */
|
|
|
|
if (patch_instruction((unsigned int *)ip, pop)) {
|
|
pr_err("Patching NOP failed.\n");
|
|
return -EPERM;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
#else /* !PPC64 */
|
|
static int
|
|
__ftrace_make_nop(struct module *mod,
|
|
struct dyn_ftrace *rec, unsigned long addr)
|
|
{
|
|
unsigned int op;
|
|
unsigned int jmp[4];
|
|
unsigned long ip = rec->ip;
|
|
unsigned long tramp;
|
|
|
|
if (probe_kernel_read(&op, (void *)ip, MCOUNT_INSN_SIZE))
|
|
return -EFAULT;
|
|
|
|
/* Make sure that that this is still a 24bit jump */
|
|
if (!is_bl_op(op)) {
|
|
pr_err("Not expected bl: opcode is %x\n", op);
|
|
return -EINVAL;
|
|
}
|
|
|
|
/* lets find where the pointer goes */
|
|
tramp = find_bl_target(ip, op);
|
|
|
|
/*
|
|
* On PPC32 the trampoline looks like:
|
|
* 0x3d, 0x80, 0x00, 0x00 lis r12,sym@ha
|
|
* 0x39, 0x8c, 0x00, 0x00 addi r12,r12,sym@l
|
|
* 0x7d, 0x89, 0x03, 0xa6 mtctr r12
|
|
* 0x4e, 0x80, 0x04, 0x20 bctr
|
|
*/
|
|
|
|
pr_devel("ip:%lx jumps to %lx", ip, tramp);
|
|
|
|
/* Find where the trampoline jumps to */
|
|
if (probe_kernel_read(jmp, (void *)tramp, sizeof(jmp))) {
|
|
pr_err("Failed to read %lx\n", tramp);
|
|
return -EFAULT;
|
|
}
|
|
|
|
pr_devel(" %08x %08x ", jmp[0], jmp[1]);
|
|
|
|
/* verify that this is what we expect it to be */
|
|
if (((jmp[0] & 0xffff0000) != 0x3d800000) ||
|
|
((jmp[1] & 0xffff0000) != 0x398c0000) ||
|
|
(jmp[2] != 0x7d8903a6) ||
|
|
(jmp[3] != 0x4e800420)) {
|
|
pr_err("Not a trampoline\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
tramp = (jmp[1] & 0xffff) |
|
|
((jmp[0] & 0xffff) << 16);
|
|
if (tramp & 0x8000)
|
|
tramp -= 0x10000;
|
|
|
|
pr_devel(" %lx ", tramp);
|
|
|
|
if (tramp != addr) {
|
|
pr_err("Trampoline location %08lx does not match addr\n",
|
|
tramp);
|
|
return -EINVAL;
|
|
}
|
|
|
|
op = PPC_INST_NOP;
|
|
|
|
if (patch_instruction((unsigned int *)ip, op))
|
|
return -EPERM;
|
|
|
|
return 0;
|
|
}
|
|
#endif /* PPC64 */
|
|
#endif /* CONFIG_MODULES */
|
|
|
|
int ftrace_make_nop(struct module *mod,
|
|
struct dyn_ftrace *rec, unsigned long addr)
|
|
{
|
|
unsigned long ip = rec->ip;
|
|
unsigned int old, new;
|
|
|
|
/*
|
|
* If the calling address is more that 24 bits away,
|
|
* then we had to use a trampoline to make the call.
|
|
* Otherwise just update the call site.
|
|
*/
|
|
if (test_24bit_addr(ip, addr)) {
|
|
/* within range */
|
|
old = ftrace_call_replace(ip, addr, 1);
|
|
new = PPC_INST_NOP;
|
|
return ftrace_modify_code(ip, old, new);
|
|
}
|
|
|
|
#ifdef CONFIG_MODULES
|
|
/*
|
|
* Out of range jumps are called from modules.
|
|
* We should either already have a pointer to the module
|
|
* or it has been passed in.
|
|
*/
|
|
if (!rec->arch.mod) {
|
|
if (!mod) {
|
|
pr_err("No module loaded addr=%lx\n", addr);
|
|
return -EFAULT;
|
|
}
|
|
rec->arch.mod = mod;
|
|
} else if (mod) {
|
|
if (mod != rec->arch.mod) {
|
|
pr_err("Record mod %p not equal to passed in mod %p\n",
|
|
rec->arch.mod, mod);
|
|
return -EINVAL;
|
|
}
|
|
/* nothing to do if mod == rec->arch.mod */
|
|
} else
|
|
mod = rec->arch.mod;
|
|
|
|
return __ftrace_make_nop(mod, rec, addr);
|
|
#else
|
|
/* We should not get here without modules */
|
|
return -EINVAL;
|
|
#endif /* CONFIG_MODULES */
|
|
}
|
|
|
|
#ifdef CONFIG_MODULES
|
|
#ifdef CONFIG_PPC64
|
|
/*
|
|
* Examine the existing instructions for __ftrace_make_call.
|
|
* They should effectively be a NOP, and follow formal constraints,
|
|
* depending on the ABI. Return false if they don't.
|
|
*/
|
|
#ifndef CC_USING_MPROFILE_KERNEL
|
|
static int
|
|
expected_nop_sequence(void *ip, unsigned int op0, unsigned int op1)
|
|
{
|
|
/*
|
|
* We expect to see:
|
|
*
|
|
* b +8
|
|
* ld r2,XX(r1)
|
|
*
|
|
* The load offset is different depending on the ABI. For simplicity
|
|
* just mask it out when doing the compare.
|
|
*/
|
|
if ((op0 != 0x48000008) || ((op1 & 0xffff0000) != 0xe8410000))
|
|
return 0;
|
|
return 1;
|
|
}
|
|
#else
|
|
static int
|
|
expected_nop_sequence(void *ip, unsigned int op0, unsigned int op1)
|
|
{
|
|
/* look for patched "NOP" on ppc64 with -mprofile-kernel */
|
|
if (op0 != PPC_INST_NOP)
|
|
return 0;
|
|
return 1;
|
|
}
|
|
#endif
|
|
|
|
static int
|
|
__ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
|
|
{
|
|
unsigned int op[2];
|
|
void *ip = (void *)rec->ip;
|
|
|
|
/* read where this goes */
|
|
if (probe_kernel_read(op, ip, sizeof(op)))
|
|
return -EFAULT;
|
|
|
|
if (!expected_nop_sequence(ip, op[0], op[1])) {
|
|
pr_err("Unexpected call sequence at %p: %x %x\n",
|
|
ip, op[0], op[1]);
|
|
return -EINVAL;
|
|
}
|
|
|
|
/* If we never set up a trampoline to ftrace_caller, then bail */
|
|
if (!rec->arch.mod->arch.tramp) {
|
|
pr_err("No ftrace trampoline\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
/* Ensure branch is within 24 bits */
|
|
if (!create_branch(ip, rec->arch.mod->arch.tramp, BRANCH_SET_LINK)) {
|
|
pr_err("Branch out of range\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (patch_branch(ip, rec->arch.mod->arch.tramp, BRANCH_SET_LINK)) {
|
|
pr_err("REL24 out of range!\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
|
|
int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
|
|
unsigned long addr)
|
|
{
|
|
return ftrace_make_call(rec, addr);
|
|
}
|
|
#endif
|
|
|
|
#else /* !CONFIG_PPC64: */
|
|
static int
|
|
__ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
|
|
{
|
|
unsigned int op;
|
|
unsigned long ip = rec->ip;
|
|
|
|
/* read where this goes */
|
|
if (probe_kernel_read(&op, (void *)ip, MCOUNT_INSN_SIZE))
|
|
return -EFAULT;
|
|
|
|
/* It should be pointing to a nop */
|
|
if (op != PPC_INST_NOP) {
|
|
pr_err("Expected NOP but have %x\n", op);
|
|
return -EINVAL;
|
|
}
|
|
|
|
/* If we never set up a trampoline to ftrace_caller, then bail */
|
|
if (!rec->arch.mod->arch.tramp) {
|
|
pr_err("No ftrace trampoline\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
/* create the branch to the trampoline */
|
|
op = create_branch((unsigned int *)ip,
|
|
rec->arch.mod->arch.tramp, BRANCH_SET_LINK);
|
|
if (!op) {
|
|
pr_err("REL24 out of range!\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
pr_devel("write to %lx\n", rec->ip);
|
|
|
|
if (patch_instruction((unsigned int *)ip, op))
|
|
return -EPERM;
|
|
|
|
return 0;
|
|
}
|
|
#endif /* CONFIG_PPC64 */
|
|
#endif /* CONFIG_MODULES */
|
|
|
|
int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
|
|
{
|
|
unsigned long ip = rec->ip;
|
|
unsigned int old, new;
|
|
|
|
/*
|
|
* If the calling address is more that 24 bits away,
|
|
* then we had to use a trampoline to make the call.
|
|
* Otherwise just update the call site.
|
|
*/
|
|
if (test_24bit_addr(ip, addr)) {
|
|
/* within range */
|
|
old = PPC_INST_NOP;
|
|
new = ftrace_call_replace(ip, addr, 1);
|
|
return ftrace_modify_code(ip, old, new);
|
|
}
|
|
|
|
#ifdef CONFIG_MODULES
|
|
/*
|
|
* Out of range jumps are called from modules.
|
|
* Being that we are converting from nop, it had better
|
|
* already have a module defined.
|
|
*/
|
|
if (!rec->arch.mod) {
|
|
pr_err("No module loaded\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
return __ftrace_make_call(rec, addr);
|
|
#else
|
|
/* We should not get here without modules */
|
|
return -EINVAL;
|
|
#endif /* CONFIG_MODULES */
|
|
}
|
|
|
|
int ftrace_update_ftrace_func(ftrace_func_t func)
|
|
{
|
|
unsigned long ip = (unsigned long)(&ftrace_call);
|
|
unsigned int old, new;
|
|
int ret;
|
|
|
|
old = *(unsigned int *)&ftrace_call;
|
|
new = ftrace_call_replace(ip, (unsigned long)func, 1);
|
|
ret = ftrace_modify_code(ip, old, new);
|
|
|
|
return ret;
|
|
}
|
|
|
|
static int __ftrace_replace_code(struct dyn_ftrace *rec, int enable)
|
|
{
|
|
unsigned long ftrace_addr = (unsigned long)FTRACE_ADDR;
|
|
int ret;
|
|
|
|
ret = ftrace_update_record(rec, enable);
|
|
|
|
switch (ret) {
|
|
case FTRACE_UPDATE_IGNORE:
|
|
return 0;
|
|
case FTRACE_UPDATE_MAKE_CALL:
|
|
return ftrace_make_call(rec, ftrace_addr);
|
|
case FTRACE_UPDATE_MAKE_NOP:
|
|
return ftrace_make_nop(NULL, rec, ftrace_addr);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
void ftrace_replace_code(int enable)
|
|
{
|
|
struct ftrace_rec_iter *iter;
|
|
struct dyn_ftrace *rec;
|
|
int ret;
|
|
|
|
for (iter = ftrace_rec_iter_start(); iter;
|
|
iter = ftrace_rec_iter_next(iter)) {
|
|
rec = ftrace_rec_iter_record(iter);
|
|
ret = __ftrace_replace_code(rec, enable);
|
|
if (ret) {
|
|
ftrace_bug(ret, rec);
|
|
return;
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Use the default ftrace_modify_all_code, but without
|
|
* stop_machine().
|
|
*/
|
|
void arch_ftrace_update_code(int command)
|
|
{
|
|
ftrace_modify_all_code(command);
|
|
}
|
|
|
|
int __init ftrace_dyn_arch_init(void)
|
|
{
|
|
return 0;
|
|
}
|
|
#endif /* CONFIG_DYNAMIC_FTRACE */
|
|
|
|
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
|
|
|
|
#ifdef CONFIG_DYNAMIC_FTRACE
|
|
extern void ftrace_graph_call(void);
|
|
extern void ftrace_graph_stub(void);
|
|
|
|
int ftrace_enable_ftrace_graph_caller(void)
|
|
{
|
|
unsigned long ip = (unsigned long)(&ftrace_graph_call);
|
|
unsigned long addr = (unsigned long)(&ftrace_graph_caller);
|
|
unsigned long stub = (unsigned long)(&ftrace_graph_stub);
|
|
unsigned int old, new;
|
|
|
|
old = ftrace_call_replace(ip, stub, 0);
|
|
new = ftrace_call_replace(ip, addr, 0);
|
|
|
|
return ftrace_modify_code(ip, old, new);
|
|
}
|
|
|
|
int ftrace_disable_ftrace_graph_caller(void)
|
|
{
|
|
unsigned long ip = (unsigned long)(&ftrace_graph_call);
|
|
unsigned long addr = (unsigned long)(&ftrace_graph_caller);
|
|
unsigned long stub = (unsigned long)(&ftrace_graph_stub);
|
|
unsigned int old, new;
|
|
|
|
old = ftrace_call_replace(ip, addr, 0);
|
|
new = ftrace_call_replace(ip, stub, 0);
|
|
|
|
return ftrace_modify_code(ip, old, new);
|
|
}
|
|
#endif /* CONFIG_DYNAMIC_FTRACE */
|
|
|
|
/*
|
|
* Hook the return address and push it in the stack of return addrs
|
|
* in current thread info. Return the address we want to divert to.
|
|
*/
|
|
unsigned long prepare_ftrace_return(unsigned long parent, unsigned long ip)
|
|
{
|
|
struct ftrace_graph_ent trace;
|
|
unsigned long return_hooker;
|
|
|
|
if (unlikely(ftrace_graph_is_dead()))
|
|
goto out;
|
|
|
|
if (unlikely(atomic_read(¤t->tracing_graph_pause)))
|
|
goto out;
|
|
|
|
return_hooker = ppc_function_entry(return_to_handler);
|
|
|
|
trace.func = ip;
|
|
trace.depth = current->curr_ret_stack + 1;
|
|
|
|
/* Only trace if the calling function expects to */
|
|
if (!ftrace_graph_entry(&trace))
|
|
goto out;
|
|
|
|
if (ftrace_push_return_trace(parent, ip, &trace.depth, 0,
|
|
NULL) == -EBUSY)
|
|
goto out;
|
|
|
|
parent = return_hooker;
|
|
out:
|
|
return parent;
|
|
}
|
|
#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 */
|
|
|
|
#ifdef PPC64_ELF_ABI_v1
|
|
char *arch_ftrace_match_adjust(char *str, const char *search)
|
|
{
|
|
if (str[0] == '.' && search[0] != '.')
|
|
return str + 1;
|
|
else
|
|
return str;
|
|
}
|
|
#endif /* PPC64_ELF_ABI_v1 */
|