OpenCloudOS-Kernel/arch/powerpc/kernel/ftrace.c

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/*
* 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.
*
*/
#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: Due to modules and __init, code can
* disappear and change, we need to protect against faulting
* as well as code changing. We do this by using the
* probe_kernel_* functions.
*
* No real locking needed, this code is run through
* kstop_machine, or before SMP starts.
*/
/* 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)
return -EINVAL;
/* replace the text with the new text */
if (probe_kernel_write((void *)ip, &new, MCOUNT_INSN_SIZE))
return -EPERM;
flush_icache_range(ip, ip + 8);
return 0;
}
/*
* Helper functions that are the same for both PPC64 and PPC32.
*/
static int test_24bit_addr(unsigned long ip, unsigned long 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 int op;
unsigned int jmp[5];
unsigned long ptr;
unsigned long ip = rec->ip;
unsigned long tramp;
int offset;
/* read where this goes */
if (probe_kernel_read(&op, (void *)ip, sizeof(int)))
return -EFAULT;
/* Make sure that that this is still a 24bit jump */
if (!is_bl_op(op)) {
printk(KERN_ERR "Not expected bl: opcode is %x\n", op);
return -EINVAL;
}
/* lets find where the pointer goes */
tramp = find_bl_target(ip, op);
/*
* On PPC64 the trampoline looks like:
* 0x3d, 0x82, 0x00, 0x00, addis r12,r2, <high>
* 0x39, 0x8c, 0x00, 0x00, addi r12,r12, <low>
* Where the bytes 2,3,6 and 7 make up the 32bit offset
* to the TOC that holds the pointer.
* to jump to.
* 0xf8, 0x41, 0x00, 0x28, std r2,40(r1)
* 0xe9, 0x6c, 0x00, 0x20, ld r11,32(r12)
* The actually address is 32 bytes from the offset
* into the TOC.
* 0xe8, 0x4c, 0x00, 0x28, ld r2,40(r12)
*/
pr_devel("ip:%lx jumps to %lx r2: %lx", ip, tramp, mod->arch.toc);
/* Find where the trampoline jumps to */
if (probe_kernel_read(jmp, (void *)tramp, sizeof(jmp))) {
printk(KERN_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) != 0x3d820000) ||
((jmp[1] & 0xffff0000) != 0x398c0000) ||
(jmp[2] != 0xf8410028) ||
(jmp[3] != 0xe96c0020) ||
(jmp[4] != 0xe84c0028)) {
printk(KERN_ERR "Not a trampoline\n");
return -EINVAL;
}
/* The bottom half is signed extended */
offset = ((unsigned)((unsigned short)jmp[0]) << 16) +
(int)((short)jmp[1]);
pr_devel(" %x ", offset);
/* get the address this jumps too */
tramp = mod->arch.toc + offset + 32;
pr_devel("toc: %lx", tramp);
if (probe_kernel_read(jmp, (void *)tramp, 8)) {
printk(KERN_ERR "Failed to read %lx\n", tramp);
return -EFAULT;
}
pr_devel(" %08x %08x\n", jmp[0], jmp[1]);
ptr = ((unsigned long)jmp[0] << 32) + jmp[1];
/* This should match what was called */
if (ptr != ppc_function_entry((void *)addr)) {
printk(KERN_ERR "addr does not match %lx\n", ptr);
return -EINVAL;
}
/*
* We want to nop the line, but the next line is
* 0xe8, 0x41, 0x00, 0x28 ld r2,40(r1)
* This needs to be turned to a nop too.
*/
if (probe_kernel_read(&op, (void *)(ip+4), MCOUNT_INSN_SIZE))
return -EFAULT;
if (op != 0xe8410028) {
printk(KERN_ERR "Next line is not ld! (%08x)\n", op);
return -EINVAL;
}
/*
* Milton Miller pointed out that we can not blindly do nops.
* 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.
*/
/*
* Replace:
* bl <tramp> <==== will be replaced with "b 1f"
* ld r2,40(r1)
* 1:
*/
op = 0x48000008; /* b +8 */
if (probe_kernel_write((void *)ip, &op, MCOUNT_INSN_SIZE))
return -EPERM;
flush_icache_range(ip, ip + 8);
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)) {
printk(KERN_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, 0x60, 0x00, 0x00 lis r11,sym@ha
* 0x39, 0x6b, 0x00, 0x00 addi r11,r11,sym@l
* 0x7d, 0x69, 0x03, 0xa6 mtctr r11
* 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))) {
printk(KERN_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) != 0x3d600000) ||
((jmp[1] & 0xffff0000) != 0x396b0000) ||
(jmp[2] != 0x7d6903a6) ||
(jmp[3] != 0x4e800420)) {
printk(KERN_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) {
printk(KERN_ERR
"Trampoline location %08lx does not match addr\n",
tramp);
return -EINVAL;
}
op = PPC_INST_NOP;
if (probe_kernel_write((void *)ip, &op, MCOUNT_INSN_SIZE))
return -EPERM;
flush_icache_range(ip, ip + 8);
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) {
printk(KERN_ERR "No module loaded addr=%lx\n",
addr);
return -EFAULT;
}
rec->arch.mod = mod;
} else if (mod) {
if (mod != rec->arch.mod) {
printk(KERN_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
static int
__ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
{
unsigned int op[2];
unsigned long ip = rec->ip;
/* read where this goes */
if (probe_kernel_read(op, (void *)ip, MCOUNT_INSN_SIZE * 2))
return -EFAULT;
/*
* It should be pointing to two nops or
* b +8; ld r2,40(r1)
*/
if (((op[0] != 0x48000008) || (op[1] != 0xe8410028)) &&
((op[0] != PPC_INST_NOP) || (op[1] != PPC_INST_NOP))) {
printk(KERN_ERR "Expected NOPs but have %x %x\n", op[0], op[1]);
return -EINVAL;
}
/* If we never set up a trampoline to ftrace_caller, then bail */
if (!rec->arch.mod->arch.tramp) {
printk(KERN_ERR "No ftrace trampoline\n");
return -EINVAL;
}
/* create the branch to the trampoline */
op[0] = create_branch((unsigned int *)ip,
rec->arch.mod->arch.tramp, BRANCH_SET_LINK);
if (!op[0]) {
printk(KERN_ERR "REL24 out of range!\n");
return -EINVAL;
}
/* ld r2,40(r1) */
op[1] = 0xe8410028;
pr_devel("write to %lx\n", rec->ip);
if (probe_kernel_write((void *)ip, op, MCOUNT_INSN_SIZE * 2))
return -EPERM;
flush_icache_range(ip, ip + 8);
return 0;
}
#else
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) {
printk(KERN_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) {
printk(KERN_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) {
printk(KERN_ERR "REL24 out of range!\n");
return -EINVAL;
}
pr_devel("write to %lx\n", rec->ip);
if (probe_kernel_write((void *)ip, &op, MCOUNT_INSN_SIZE))
return -EPERM;
flush_icache_range(ip, ip + 8);
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) {
printk(KERN_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;
}
int __init ftrace_dyn_arch_init(void *data)
{
/* caller expects data to be zero */
unsigned long *p = data;
*p = 0;
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 */
#ifdef CONFIG_PPC64
extern void mod_return_to_handler(void);
#endif
/*
* Hook the return address and push it in the stack of return addrs
* in current thread info.
*/
void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr)
{
unsigned long old;
int faulted;
struct ftrace_graph_ent trace;
unsigned long return_hooker = (unsigned long)&return_to_handler;
if (unlikely(atomic_read(&current->tracing_graph_pause)))
return;
#ifdef CONFIG_PPC64
/* non core kernel code needs to save and restore the TOC */
if (REGION_ID(self_addr) != KERNEL_REGION_ID)
return_hooker = (unsigned long)&mod_return_to_handler;
#endif
return_hooker = ppc_function_entry((void *)return_hooker);
/*
* Protect against fault, even if it shouldn't
* happen. This tool is too much intrusive to
* ignore such a protection.
*/
asm volatile(
"1: " PPC_LL "%[old], 0(%[parent])\n"
"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;
}
function-graph: add stack frame test In case gcc does something funny with the stack frames, or the return from function code, we would like to detect that. An arch may implement passing of a variable that is unique to the function and can be saved on entering a function and can be tested when exiting the function. Usually the frame pointer can be used for this purpose. This patch also implements this for x86. Where it passes in the stack frame of the parent function, and will test that frame on exit. There was a case in x86_32 with optimize for size (-Os) where, for a few functions, gcc would align the stack frame and place a copy of the return address into it. The function graph tracer modified the copy and not the actual return address. On return from the funtion, it did not go to the tracer hook, but returned to the parent. This broke the function graph tracer, because the return of the parent (where gcc did not do this funky manipulation) returned to the location that the child function was suppose to. This caused strange kernel crashes. This test detected the problem and pointed out where the issue was. This modifies the parameters of one of the functions that the arch specific code calls, so it includes changes to arch code to accommodate the new prototype. Note, I notice that the parsic arch implements its own push_return_trace. This is now a generic function and the ftrace_push_return_trace should be used instead. This patch does not touch that code. Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Helge Deller <deller@gmx.de> Cc: Kyle McMartin <kyle@mcmartin.ca> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2009-06-19 00:45:08 +08:00
if (ftrace_push_return_trace(old, self_addr, &trace.depth, 0) == -EBUSY) {
*parent = old;
return;
}
trace.func = self_addr;
/* Only trace if the calling function expects to */
if (!ftrace_graph_entry(&trace)) {
current->curr_ret_stack--;
*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 */