1 files changed, 432 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/trace/ftrace.c b/arch/powerpc/kernel/trace/ftrace.c
new file mode 100644
index 000000000..82010629c
--- /dev/null
+++ b/arch/powerpc/kernel/trace/ftrace.c
@@ -0,0 +1,432 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * 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>
+#include <asm/inst.h>
+
+#define	NUM_FTRACE_TRAMPS	2
+static unsigned long ftrace_tramps[NUM_FTRACE_TRAMPS];
+
+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(&current->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 */