02424d8966
This patch implements the raw syscall tracepoints on PowerPC and exports
them for ftrace syscalls to use.
To minimise reworking existing code, I slightly re-ordered the thread
info flags such that the new TIF_SYSCALL_TRACEPOINT bit would still fit
within the 16 bits of the andi. instruction's UI field. The instructions
in question are in /arch/powerpc/kernel/entry_{32,64}.S to and the
_TIF_SYSCALL_T_OR_A with the thread flags to see if system call tracing
is enabled.
In the case of 64bit PowerPC, arch_syscall_addr and
arch_syscall_match_sym_name are overridden to allow ftrace syscalls to
work given the unusual system call table structure and symbol names that
start with a period.
Signed-off-by: Ian Munsie <imunsie@au1.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
610 lines
14 KiB
C
610 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.
|
|
*
|
|
*/
|
|
|
|
#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(¤t->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;
|
|
}
|
|
|
|
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 */
|