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