#ifdef CONFIG_DYNAMIC_FTRACE
+
+/*
+ * We generally only have a single long_branch tramp and at most 2 or 3 plt
+ * tramps generated. But, we don't use the plt tramps currently. We also allot
+ * 2 tramps after .text and .init.text. So, we only end up with around 3 usable
+ * tramps in total. Set aside 8 just to be sure.
+ */
+#define NUM_FTRACE_TRAMPS 8
+static unsigned long ftrace_tramps[NUM_FTRACE_TRAMPS];
+
static unsigned int
ftrace_call_replace(unsigned long ip, unsigned long addr, int link)
{
return create_branch((unsigned int *)ip, addr, 0);
}
-#ifdef CONFIG_MODULES
-
static int is_bl_op(unsigned int op)
{
return (op & 0xfc000003) == 0x48000001;
}
+static int is_b_op(unsigned int op)
+{
+ return (op & 0xfc000003) == 0x48000000;
+}
+
static unsigned long find_bl_target(unsigned long ip, unsigned int op)
{
static int offset;
return ip + (long)offset;
}
+#ifdef CONFIG_MODULES
#ifdef CONFIG_PPC64
static int
__ftrace_make_nop(struct module *mod,
#endif /* PPC64 */
#endif /* CONFIG_MODULES */
+static unsigned long find_ftrace_tramp(unsigned long ip)
+{
+ int i;
+
+ /*
+ * We have the compiler generated long_branch tramps at the end
+ * and we prefer those
+ */
+ for (i = NUM_FTRACE_TRAMPS - 1; i >= 0; i--)
+ if (!ftrace_tramps[i])
+ continue;
+ else if (create_branch((void *)ip, ftrace_tramps[i], 0))
+ return ftrace_tramps[i];
+
+ return 0;
+}
+
+static int 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 0;
+ }
+
+ return -1;
+}
+
+/*
+ * If this is a compiler generated long_branch trampoline (essentially, a
+ * trampoline that has a branch to _mcount()), we re-write the branch to
+ * instead go to ftrace_[regs_]caller() and note down the location of this
+ * trampoline.
+ */
+static int setup_mcount_compiler_tramp(unsigned long tramp)
+{
+ int i, op;
+ unsigned long ptr;
+ static unsigned long ftrace_plt_tramps[NUM_FTRACE_TRAMPS];
+
+ /* Is this a known long jump tramp? */
+ for (i = 0; i < NUM_FTRACE_TRAMPS; i++)
+ if (!ftrace_tramps[i])
+ break;
+ else if (ftrace_tramps[i] == tramp)
+ return 0;
+
+ /* Is this a known plt tramp? */
+ for (i = 0; i < NUM_FTRACE_TRAMPS; i++)
+ if (!ftrace_plt_tramps[i])
+ break;
+ else if (ftrace_plt_tramps[i] == tramp)
+ return -1;
+
+ /* New trampoline -- read where this goes */
+ if (probe_kernel_read(&op, (void *)tramp, sizeof(int))) {
+ pr_debug("Fetching opcode failed.\n");
+ return -1;
+ }
+
+ /* Is this a 24 bit branch? */
+ if (!is_b_op(op)) {
+ pr_debug("Trampoline is not a long branch tramp.\n");
+ return -1;
+ }
+
+ /* lets find where the pointer goes */
+ ptr = find_bl_target(tramp, op);
+
+ if (ptr != ppc_global_function_entry((void *)_mcount)) {
+ pr_debug("Trampoline target %p is not _mcount\n", (void *)ptr);
+ return -1;
+ }
+
+ /* Let's re-write the tramp to go to ftrace_[regs_]caller */
+#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
+ ptr = ppc_global_function_entry((void *)ftrace_regs_caller);
+#else
+ ptr = ppc_global_function_entry((void *)ftrace_caller);
+#endif
+ if (!create_branch((void *)tramp, ptr, 0)) {
+ pr_debug("%ps is not reachable from existing mcount tramp\n",
+ (void *)ptr);
+ return -1;
+ }
+
+ if (patch_branch((unsigned int *)tramp, ptr, 0)) {
+ pr_debug("REL24 out of range!\n");
+ return -1;
+ }
+
+ if (add_ftrace_tramp(tramp)) {
+ pr_debug("No tramp locations left\n");
+ return -1;
+ }
+
+ return 0;
+}
+
+static int __ftrace_make_nop_kernel(struct dyn_ftrace *rec, unsigned long addr)
+{
+ unsigned long tramp, ip = rec->ip;
+ unsigned int op;
+
+ /* Read where this goes */
+ if (probe_kernel_read(&op, (void *)ip, sizeof(int))) {
+ pr_err("Fetching opcode failed.\n");
+ 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;
+ }
+
+ /* Let's find where the pointer goes */
+ tramp = find_bl_target(ip, op);
+
+ pr_devel("ip:%lx jumps to %lx", ip, tramp);
+
+ if (setup_mcount_compiler_tramp(tramp)) {
+ /* Are other trampolines reachable? */
+ if (!find_ftrace_tramp(ip)) {
+ pr_err("No ftrace trampolines reachable from %ps\n",
+ (void *)ip);
+ return -EINVAL;
+ }
+ }
+
+ if (patch_instruction((unsigned int *)ip, PPC_INST_NOP)) {
+ pr_err("Patching NOP failed.\n");
+ return -EPERM;
+ }
+
+ return 0;
+}
+
int ftrace_make_nop(struct module *mod,
struct dyn_ftrace *rec, unsigned long addr)
{
old = ftrace_call_replace(ip, addr, 1);
new = PPC_INST_NOP;
return ftrace_modify_code(ip, old, new);
- }
+ } else if (core_kernel_text(ip))
+ return __ftrace_make_nop_kernel(rec, addr);
#ifdef CONFIG_MODULES
/*
#endif /* CONFIG_PPC64 */
#endif /* CONFIG_MODULES */
+static int __ftrace_make_call_kernel(struct dyn_ftrace *rec, unsigned long addr)
+{
+ unsigned int op;
+ void *ip = (void *)rec->ip;
+ unsigned long tramp, entry, ptr;
+
+ /* Make sure we're being asked to patch branch to a known ftrace addr */
+ entry = ppc_global_function_entry((void *)ftrace_caller);
+ ptr = ppc_global_function_entry((void *)addr);
+
+ if (ptr != entry) {
+#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
+ entry = ppc_global_function_entry((void *)ftrace_regs_caller);
+ if (ptr != entry) {
+#endif
+ pr_err("Unknown ftrace addr to patch: %ps\n", (void *)ptr);
+ return -EINVAL;
+#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
+ }
+#endif
+ }
+
+ /* Make sure we have a nop */
+ if (probe_kernel_read(&op, ip, sizeof(op))) {
+ pr_err("Unable to read ftrace location %p\n", ip);
+ return -EFAULT;
+ }
+
+ if (op != PPC_INST_NOP) {
+ pr_err("Unexpected call sequence at %p: %x\n", ip, op);
+ return -EINVAL;
+ }
+
+ tramp = find_ftrace_tramp((unsigned long)ip);
+ if (!tramp) {
+ pr_err("No ftrace trampolines reachable from %ps\n", ip);
+ return -EINVAL;
+ }
+
+ if (patch_branch(ip, tramp, BRANCH_SET_LINK)) {
+ pr_err("Error patching branch to ftrace tramp!\n");
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
{
unsigned long ip = rec->ip;
old = PPC_INST_NOP;
new = ftrace_call_replace(ip, addr, 1);
return ftrace_modify_code(ip, old, new);
- }
+ } else if (core_kernel_text(ip))
+ return __ftrace_make_call_kernel(rec, addr);
#ifdef CONFIG_MODULES
/*
old = ftrace_call_replace(ip, old_addr, 1);
new = ftrace_call_replace(ip, addr, 1);
return ftrace_modify_code(ip, old, new);
+ } else if (core_kernel_text(ip)) {
+ /*
+ * We always patch out of range locations to go to the regs
+ * variant, so there is nothing to do here
+ */
+ return 0;
}
#ifdef CONFIG_MODULES
ftrace_modify_all_code(command);
}
+#ifdef CONFIG_PPC64
+#define PACATOC offsetof(struct paca_struct, kernel_toc)
+
+#define PPC_LO(v) ((v) & 0xffff)
+#define PPC_HI(v) (((v) >> 16) & 0xffff)
+#define PPC_HA(v) PPC_HI ((v) + 0x8000)
+
+extern unsigned int ftrace_tramp_text[], ftrace_tramp_init[];
+
+int __init ftrace_dyn_arch_init(void)
+{
+ int i;
+ unsigned int *tramp[] = { ftrace_tramp_text, ftrace_tramp_init };
+ u32 stub_insns[] = {
+ 0xe98d0000 | PACATOC, /* ld r12,PACATOC(r13) */
+ 0x3d8c0000, /* addis r12,r12,<high> */
+ 0x398c0000, /* addi r12,r12,<low> */
+ 0x7d8903a6, /* mtctr r12 */
+ 0x4e800420, /* bctr */
+ };
+#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
+ unsigned long addr = ppc_global_function_entry((void *)ftrace_regs_caller);
+#else
+ unsigned long addr = ppc_global_function_entry((void *)ftrace_caller);
+#endif
+ long reladdr = addr - kernel_toc_addr();
+
+ if (reladdr > 0x7FFFFFFF || reladdr < -(0x80000000L)) {
+ 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]);
+ }
+
+ return 0;
+}
+#else
int __init ftrace_dyn_arch_init(void)
{
return 0;
}
+#endif
#endif /* CONFIG_DYNAMIC_FTRACE */
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
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