// SPDX-License-Identifier: GPL-2.0
/*
* Code for replacing ftrace calls with jumps.
*
* Copyright (C) 2007-2008 Steven Rostedt <[email protected]>
*
* 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>
#include <asm/inst.h>
#include <asm/sections.h>
#define NUM_FTRACE_TRAMPS 2
static unsigned long ftrace_tramps[NUM_FTRACE_TRAMPS];
unsigned long ftrace_call_adjust(unsigned long addr)
{
if (addr >= (unsigned long)__exittext_begin && addr < (unsigned long)__exittext_end)
return 0;
if (IS_ENABLED(CONFIG_ARCH_USING_PATCHABLE_FUNCTION_ENTRY))
addr += MCOUNT_INSN_SIZE;
return addr;
}
static ppc_inst_t ftrace_create_branch_inst(unsigned long ip, unsigned long addr, int link)
{
ppc_inst_t op;
WARN_ON(!is_offset_in_branch_range(addr - ip));
create_branch(&op, (u32 *)ip, addr, link ? BRANCH_SET_LINK : 0);
return op;
}
static inline int ftrace_read_inst(unsigned long ip, ppc_inst_t *op)
{
if (copy_inst_from_kernel_nofault(op, (void *)ip)) {
pr_err("0x%lx: fetching instruction failed\n", ip);
return -EFAULT;
}
return 0;
}
static inline int ftrace_validate_inst(unsigned long ip, ppc_inst_t inst)
{
ppc_inst_t op;
int ret;
ret = ftrace_read_inst(ip, &op);
if (!ret && !ppc_inst_equal(op, inst)) {
pr_err("0x%lx: expected (%08lx) != found (%08lx)\n",
ip, ppc_inst_as_ulong(inst), ppc_inst_as_ulong(op));
ret = -EINVAL;
}
return ret;
}
static inline int ftrace_modify_code(unsigned long ip, ppc_inst_t old, ppc_inst_t new)
{
int ret = ftrace_validate_inst(ip, old);
if (!ret)
ret = patch_instruction((u32 *)ip, new);
return ret;
}
static int is_bl_op(ppc_inst_t op)
{
return (ppc_inst_val(op) & ~PPC_LI_MASK) == PPC_RAW_BL(0);
}
static unsigned long find_ftrace_tramp(unsigned long ip)
{
int i;
for (i = 0; i < NUM_FTRACE_TRAMPS; i++)
if (!ftrace_tramps[i])
continue;
else if (is_offset_in_branch_range(ftrace_tramps[i] - ip))
return ftrace_tramps[i];
return 0;
}
static int ftrace_get_call_inst(struct dyn_ftrace *rec, unsigned long addr, ppc_inst_t *call_inst)
{
unsigned long ip = rec->ip;
unsigned long stub;
if (is_offset_in_branch_range(addr - ip)) {
/* Within range */
stub = addr;
#ifdef CONFIG_MODULES
} else if (rec->arch.mod) {
/* Module code would be going to one of the module stubs */
stub = (addr == (unsigned long)ftrace_caller ? rec->arch.mod->arch.tramp :
rec->arch.mod->arch.tramp_regs);
#endif
} else if (core_kernel_text(ip)) {
/* We would be branching to one of our ftrace stubs */
stub = find_ftrace_tramp(ip);
if (!stub) {
pr_err("0x%lx: No ftrace stubs reachable\n", ip);
return -EINVAL;
}
} else {
return -EINVAL;
}
*call_inst = ftrace_create_branch_inst(ip, stub, 1);
return 0;
}
#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, unsigned long addr)
{
/* This should never be called since we override ftrace_replace_code() */
WARN_ON(1);
return -EINVAL;
}
#endif
int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
{
ppc_inst_t old, new;
int ret;
/* This can only ever be called during module load */
if (WARN_ON(!IS_ENABLED(CONFIG_MODULES) || core_kernel_text(rec->ip)))
return -EINVAL;
old = ppc_inst(PPC_RAW_NOP());
ret = ftrace_get_call_inst(rec, addr, &new);
if (ret)
return ret;
return ftrace_modify_code(rec->ip, old, new);
}
int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, unsigned long addr)
{
/*
* This should never be called since we override ftrace_replace_code(),
* as well as ftrace_init_nop()
*/
WARN_ON(1);
return -EINVAL;
}
void ftrace_replace_code(int enable)
{
ppc_inst_t old, new, call_inst, new_call_inst;
ppc_inst_t nop_inst = ppc_inst(PPC_RAW_NOP());
unsigned long ip, new_addr, addr;
struct ftrace_rec_iter *iter;
struct dyn_ftrace *rec;
int ret = 0, update;
for_ftrace_rec_iter(iter) {
rec = ftrace_rec_iter_record(iter);
ip = rec->ip;
if (rec->flags & FTRACE_FL_DISABLED && !(rec->flags & FTRACE_FL_ENABLED))
continue;
addr = ftrace_get_addr_curr(rec);
new_addr = ftrace_get_addr_new(rec);
update = ftrace_update_record(rec, enable);
switch (update) {
case FTRACE_UPDATE_IGNORE:
default:
continue;
case FTRACE_UPDATE_MODIFY_CALL:
ret = ftrace_get_call_inst(rec, new_addr, &new_call_inst);
ret |= ftrace_get_call_inst(rec, addr, &call_inst);
old = call_inst;
new = new_call_inst;
break;
case FTRACE_UPDATE_MAKE_NOP:
ret = ftrace_get_call_inst(rec, addr, &call_inst);
old = call_inst;
new = nop_inst;
break;
case FTRACE_UPDATE_MAKE_CALL:
ret = ftrace_get_call_inst(rec, new_addr, &call_inst);
old = nop_inst;
new = call_inst;
break;
}
if (!ret)
ret = ftrace_modify_code(ip, old, new);
if (ret)
goto out;
}
out:
if (ret)
ftrace_bug(ret, rec);
return;
}
int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec)
{
unsigned long addr, ip = rec->ip;
ppc_inst_t old, new;
int ret = 0;
/* Verify instructions surrounding the ftrace location */
if (IS_ENABLED(CONFIG_ARCH_USING_PATCHABLE_FUNCTION_ENTRY)) {
/* Expect nops */
ret = ftrace_validate_inst(ip - 4, ppc_inst(PPC_RAW_NOP()));
if (!ret)
ret = ftrace_validate_inst(ip, ppc_inst(PPC_RAW_NOP()));
} else if (IS_ENABLED(CONFIG_PPC32)) {
/* Expected sequence: 'mflr r0', 'stw r0,4(r1)', 'bl _mcount' */
ret = ftrace_validate_inst(ip - 8, ppc_inst(PPC_RAW_MFLR(_R0)));
if (!ret)
ret = ftrace_validate_inst(ip - 4, ppc_inst(PPC_RAW_STW(_R0, _R1, 4)));
} else if (IS_ENABLED(CONFIG_MPROFILE_KERNEL)) {
/* Expected sequence: 'mflr r0', ['std r0,16(r1)'], 'bl _mcount' */
ret = ftrace_read_inst(ip - 4, &old);
if (!ret && !ppc_inst_equal(old, ppc_inst(PPC_RAW_MFLR(_R0)))) {
ret = ftrace_validate_inst(ip - 8, ppc_inst(PPC_RAW_MFLR(_R0)));
ret |= ftrace_validate_inst(ip - 4, ppc_inst(PPC_RAW_STD(_R0, _R1, 16)));
}
} else {
return -EINVAL;
}
if (ret)
return ret;
if (!core_kernel_text(ip)) {
if (!mod) {
pr_err("0x%lx: No module provided for non-kernel address\n", ip);
return -EFAULT;
}
rec->arch.mod = mod;
}
/* Nop-out the ftrace location */
new = ppc_inst(PPC_RAW_NOP());
addr = MCOUNT_ADDR;
if (IS_ENABLED(CONFIG_ARCH_USING_PATCHABLE_FUNCTION_ENTRY)) {
/* we instead patch-in the 'mflr r0' */
old = ppc_inst(PPC_RAW_NOP());
new = ppc_inst(PPC_RAW_MFLR(_R0));
ret = ftrace_modify_code(ip - 4, old, new);
} else if (is_offset_in_branch_range(addr - ip)) {
/* Within range */
old = ftrace_create_branch_inst(ip, addr, 1);
ret = ftrace_modify_code(ip, old, new);
} else if (core_kernel_text(ip) || (IS_ENABLED(CONFIG_MODULES) && mod)) {
/*
* We would be branching to a linker-generated stub, or to the module _mcount
* stub. Let's just confirm we have a 'bl' here.
*/
ret = ftrace_read_inst(ip, &old);
if (ret)
return ret;
if (!is_bl_op(old)) {
pr_err("0x%lx: expected (bl) != found (%08lx)\n", ip, ppc_inst_as_ulong(old));
return -EINVAL;
}
ret = patch_instruction((u32 *)ip, new);
} else {
return -EINVAL;
}
return ret;
}
int ftrace_update_ftrace_func(ftrace_func_t func)
{
unsigned long ip = (unsigned long)(&ftrace_call);
ppc_inst_t old, new;
int ret;
old = ppc_inst_read((u32 *)&ftrace_call);
new = ftrace_create_branch_inst(ip, ppc_function_entry(func), 1);
ret = ftrace_modify_code(ip, old, new);
/* Also update the regs callback function */
if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS) && !ret) {
ip = (unsigned long)(&ftrace_regs_call);
old = ppc_inst_read((u32 *)&ftrace_regs_call);
new = ftrace_create_branch_inst(ip, ppc_function_entry(func), 1);
ret = ftrace_modify_code(ip, old, new);
}
return ret;
}
/*
* Use the default ftrace_modify_all_code, but without
* stop_machine().
*/
void arch_ftrace_update_code(int command)
{
ftrace_modify_all_code(command);
}
void ftrace_free_init_tramp(void)
{
int i;
for (i = 0; i < NUM_FTRACE_TRAMPS && ftrace_tramps[i]; i++)
if (ftrace_tramps[i] == (unsigned long)ftrace_tramp_init) {
ftrace_tramps[i] = 0;
return;
}
}
static void __init add_ftrace_tramp(unsigned long tramp)
{
int i;
for (i = 0; i < NUM_FTRACE_TRAMPS; i++)
if (!ftrace_tramps[i]) {
ftrace_tramps[i] = tramp;
return;
}
}
int __init ftrace_dyn_arch_init(void)
{
unsigned int *tramp[] = { ftrace_tramp_text, ftrace_tramp_init };
unsigned long addr = FTRACE_REGS_ADDR;
long reladdr;
int i;
u32 stub_insns[] = {
#ifdef CONFIG_PPC_KERNEL_PCREL
/* pla r12,addr */
PPC_PREFIX_MLS | __PPC_PRFX_R(1),
PPC_INST_PADDI | ___PPC_RT(_R12),
PPC_RAW_MTCTR(_R12),
PPC_RAW_BCTR()
#elif defined(CONFIG_PPC64)
PPC_RAW_LD(_R12, _R13, offsetof(struct paca_struct, kernel_toc)),
PPC_RAW_ADDIS(_R12, _R12, 0),
PPC_RAW_ADDI(_R12, _R12, 0),
PPC_RAW_MTCTR(_R12),
PPC_RAW_BCTR()
#else
PPC_RAW_LIS(_R12, 0),
PPC_RAW_ADDI(_R12, _R12, 0),
PPC_RAW_MTCTR(_R12),
PPC_RAW_BCTR()
#endif
};
if (IS_ENABLED(CONFIG_PPC_KERNEL_PCREL)) {
for (i = 0; i < 2; i++) {
reladdr = addr - (unsigned long)tramp[i];
if (reladdr >= (long)SZ_8G || reladdr < -(long)SZ_8G) {
pr_err("Address of %ps out of range of pcrel address.\n",
(void *)addr);
return -1;
}
memcpy(tramp[i], stub_insns, sizeof(stub_insns));
tramp[i][0] |= IMM_H18(reladdr);
tramp[i][1] |= IMM_L(reladdr);
add_ftrace_tramp((unsigned long)tramp[i]);
}
} else if (IS_ENABLED(CONFIG_PPC64)) {
reladdr = addr - kernel_toc_addr();
if (reladdr >= (long)SZ_2G || reladdr < -(long long)SZ_2G) {
pr_err("Address of %ps out of range of kernel_toc.\n",
(void *)addr);
return -1;
}
for (i = 0; i < 2; i++) {
memcpy(tramp[i], stub_insns, sizeof(stub_insns));
tramp[i][1] |= PPC_HA(reladdr);
tramp[i][2] |= PPC_LO(reladdr);
add_ftrace_tramp((unsigned long)tramp[i]);
}
} else {
for (i = 0; i < 2; i++) {
memcpy(tramp[i], stub_insns, sizeof(stub_insns));
tramp[i][0] |= PPC_HA(addr);
tramp[i][1] |= PPC_LO(addr);
add_ftrace_tramp((unsigned long)tramp[i]);
}
}
return 0;
}
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
struct ftrace_ops *op, struct ftrace_regs *fregs)
{
unsigned long sp = fregs->regs.gpr[1];
int bit;
if (unlikely(ftrace_graph_is_dead()))
goto out;
if (unlikely(atomic_read(¤t->tracing_graph_pause)))
goto out;
bit = ftrace_test_recursion_trylock(ip, parent_ip);
if (bit < 0)
goto out;
if (!function_graph_enter(parent_ip, ip, 0, (unsigned long *)sp))
parent_ip = ppc_function_entry(return_to_handler);
ftrace_test_recursion_unlock(bit);
out:
fregs->regs.link = parent_ip;
}
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
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