--- /dev/null
+/*
+ * 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: 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 (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 int op;
+ unsigned long entry, ptr;
+ unsigned long ip = rec->ip;
+ void *tramp;
+
+ /* 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)) {
+ pr_err("Not expected bl: opcode is %x\n", op);
+ return -EINVAL;
+ }
+
+ /* lets find where the pointer goes */
+ tramp = (void *)find_bl_target(ip, op);
+
+ pr_devel("ip:%lx jumps to %p", ip, tramp);
+
+ if (!is_module_trampoline(tramp)) {
+ pr_err("Not a trampoline\n");
+ return -EINVAL;
+ }
+
+ 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;
+ }
+
+ /*
+ * 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.
+ */
+ op = 0x48000008; /* b +8 */
+
+ if (patch_instruction((unsigned int *)ip, op))
+ 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
+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;
+
+ /*
+ * 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 ((op[0] != 0x48000008) || ((op[1] & 0xffff0000) != 0xe8410000)) {
+ pr_err("Unexpected call sequence: %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) {
+ 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;
+}
+#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) {
+ 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;
+ }
+ }
+}
+
+void arch_ftrace_update_code(int command)
+{
+ if (command & FTRACE_UPDATE_CALLS)
+ ftrace_replace_code(1);
+ else if (command & FTRACE_DISABLE_CALLS)
+ ftrace_replace_code(0);
+
+ if (command & FTRACE_UPDATE_TRACE_FUNC)
+ ftrace_update_ftrace_func(ftrace_trace_function);
+
+ if (command & FTRACE_START_FUNC_RET)
+ ftrace_enable_ftrace_graph_caller();
+ else if (command & FTRACE_STOP_FUNC_RET)
+ ftrace_disable_ftrace_graph_caller();
+}
+
+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) == -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 */
Code Review / kvmfornfv.git / blobdiff