Merge tag 'powerpc-4.11-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux

Pull powerpc updates from Michael Ellerman:
 "Highlights include:

   - Support for direct mapped LPC on POWER9, giving Linux direct access
     to devices that may be on there such as a UART.

   - Memory hotplug support for the Power9 Radix MMU.

   - Add new AUX vectors describing the processor's cache geometry, to
     be used by glibc.

   - The ability for a guest to ask the hypervisor to resize the guest's
     hash table, and in addition support for doing so automatically when
     memory is hotplugged into/out-of the guest. This allows the hash
     table to be sized based on the current memory usage of the guest,
     rather than the maximum possible memory usage.

   - Implementation of optprobes (kprobe optimisation) for powerpc.

  In addition there's the topic branch shared with the KVM tree, which
  includes support for guests to use the Radix MMU on Power9.

  Thanks to:
    Alistair Popple, Andrew Donnellan, Aneesh Kumar K.V, Anju T, Anton
    Blanchard, Benjamin Herrenschmidt, Chris Packham, Daniel Axtens,
    Daniel Borkmann, David Gibson, Finn Thain, Gautham R. Shenoy, Gavin
    Shan, Greg Kurz, Joel Stanley, John Allen, Madhavan Srinivasan,
    Mahesh Salgaonkar, Markus Elfring, Michael Neuling, Nathan Fontenot,
    Naveen N. Rao, Nicholas Piggin, Paul Mackerras, Ravi Bangoria, Reza
    Arbab, Shailendra Singh, Vaibhav Jain, Wei Yongjun"

* tag 'powerpc-4.11-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (129 commits)
  powerpc/mm/radix: Skip ptesync in pte update helpers
  powerpc/mm/radix: Use ptep_get_and_clear_full when clearing pte for full mm
  powerpc/mm/radix: Update pte update sequence for pte clear case
  powerpc/mm: Update PROTFAULT handling in the page fault path
  powerpc/xmon: Fix data-breakpoint
  powerpc/mm: Fix build break with BOOK3S_64=n and MEMORY_HOTPLUG=y
  powerpc/mm: Fix build break when CMA=n && SPAPR_TCE_IOMMU=y
  powerpc/mm: Fix build break with RADIX=y & HUGETLBFS=n
  powerpc/pseries: Fix typo in parameter description
  powerpc/kprobes: Remove kprobe_exceptions_notify()
  kprobes: Introduce weak variant of kprobe_exceptions_notify()
  powerpc/ftrace: Fix confusing help text for DISABLE_MPROFILE_KERNEL
  powerpc/powernv: Fix opal_exit tracepoint opcode
  powerpc: Add a prototype for mcount() so it can be versioned
  powerpc: Drop GPL from of_node_to_nid() export to match other arches
  powerpc/kprobes: Optimize kprobe in kretprobe_trampoline()
  powerpc/kprobes: Implement Optprobes
  powerpc/kprobes: Fixes for kprobe_lookup_name() on BE
  powerpc: Add helper to check if offset is within relative branch range
  powerpc/bpf: Introduce __PPC_SH64()
  ...

1 files changed, 347 insertions, 0 deletions

diff --git a/arch/powerpc/kernel/optprobes.c b/arch/powerpc/kernel/optprobes.c
new file mode 100644
index 000000000000..2282bf4e63cd
--- /dev/null
+++ b/arch/powerpc/kernel/optprobes.c
@@ -0,0 +1,347 @@
+/*
+ * Code for Kernel probes Jump optimization.
+ *
+ * Copyright 2017, Anju T, IBM Corp.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/kprobes.h>
+#include <linux/jump_label.h>
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/list.h>
+#include <asm/kprobes.h>
+#include <asm/ptrace.h>
+#include <asm/cacheflush.h>
+#include <asm/code-patching.h>
+#include <asm/sstep.h>
+#include <asm/ppc-opcode.h>
+
+#define TMPL_CALL_HDLR_IDX	\
+	(optprobe_template_call_handler - optprobe_template_entry)
+#define TMPL_EMULATE_IDX	\
+	(optprobe_template_call_emulate - optprobe_template_entry)
+#define TMPL_RET_IDX		\
+	(optprobe_template_ret - optprobe_template_entry)
+#define TMPL_OP_IDX		\
+	(optprobe_template_op_address - optprobe_template_entry)
+#define TMPL_INSN_IDX		\
+	(optprobe_template_insn - optprobe_template_entry)
+#define TMPL_END_IDX		\
+	(optprobe_template_end - optprobe_template_entry)
+
+DEFINE_INSN_CACHE_OPS(ppc_optinsn);
+
+static bool insn_page_in_use;
+
+static void *__ppc_alloc_insn_page(void)
+{
+	if (insn_page_in_use)
+		return NULL;
+	insn_page_in_use = true;
+	return &optinsn_slot;
+}
+
+static void __ppc_free_insn_page(void *page __maybe_unused)
+{
+	insn_page_in_use = false;
+}
+
+struct kprobe_insn_cache kprobe_ppc_optinsn_slots = {
+	.mutex = __MUTEX_INITIALIZER(kprobe_ppc_optinsn_slots.mutex),
+	.pages = LIST_HEAD_INIT(kprobe_ppc_optinsn_slots.pages),
+	/* insn_size initialized later */
+	.alloc = __ppc_alloc_insn_page,
+	.free = __ppc_free_insn_page,
+	.nr_garbage = 0,
+};
+
+/*
+ * Check if we can optimize this probe. Returns NIP post-emulation if this can
+ * be optimized and 0 otherwise.
+ */
+static unsigned long can_optimize(struct kprobe *p)
+{
+	struct pt_regs regs;
+	struct instruction_op op;
+	unsigned long nip = 0;
+
+	/*
+	 * kprobe placed for kretprobe during boot time
+	 * has a 'nop' instruction, which can be emulated.
+	 * So further checks can be skipped.
+	 */
+	if (p->addr == (kprobe_opcode_t *)&kretprobe_trampoline)
+		return (unsigned long)p->addr + sizeof(kprobe_opcode_t);
+
+	/*
+	 * We only support optimizing kernel addresses, but not
+	 * module addresses.
+	 *
+	 * FIXME: Optimize kprobes placed in module addresses.
+	 */
+	if (!is_kernel_addr((unsigned long)p->addr))
+		return 0;
+
+	memset(&regs, 0, sizeof(struct pt_regs));
+	regs.nip = (unsigned long)p->addr;
+	regs.trap = 0x0;
+	regs.msr = MSR_KERNEL;
+
+	/*
+	 * Kprobe placed in conditional branch instructions are
+	 * not optimized, as we can't predict the nip prior with
+	 * dummy pt_regs and can not ensure that the return branch
+	 * from detour buffer falls in the range of address (i.e 32MB).
+	 * A branch back from trampoline is set up in the detour buffer
+	 * to the nip returned by the analyse_instr() here.
+	 *
+	 * Ensure that the instruction is not a conditional branch,
+	 * and that can be emulated.
+	 */
+	if (!is_conditional_branch(*p->ainsn.insn) &&
+			analyse_instr(&op, &regs, *p->ainsn.insn))
+		nip = regs.nip;
+
+	return nip;
+}
+
+static void optimized_callback(struct optimized_kprobe *op,
+			       struct pt_regs *regs)
+{
+	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+	unsigned long flags;
+
+	/* This is possible if op is under delayed unoptimizing */
+	if (kprobe_disabled(&op->kp))
+		return;
+
+	local_irq_save(flags);
+	hard_irq_disable();
+
+	if (kprobe_running()) {
+		kprobes_inc_nmissed_count(&op->kp);
+	} else {
+		__this_cpu_write(current_kprobe, &op->kp);
+		regs->nip = (unsigned long)op->kp.addr;
+		kcb->kprobe_status = KPROBE_HIT_ACTIVE;
+		opt_pre_handler(&op->kp, regs);
+		__this_cpu_write(current_kprobe, NULL);
+	}
+
+	/*
+	 * No need for an explicit __hard_irq_enable() here.
+	 * local_irq_restore() will re-enable interrupts,
+	 * if they were hard disabled.
+	 */
+	local_irq_restore(flags);
+}
+NOKPROBE_SYMBOL(optimized_callback);
+
+void arch_remove_optimized_kprobe(struct optimized_kprobe *op)
+{
+	if (op->optinsn.insn) {
+		free_ppc_optinsn_slot(op->optinsn.insn, 1);
+		op->optinsn.insn = NULL;
+	}
+}
+
+/*
+ * emulate_step() requires insn to be emulated as
+ * second parameter. Load register 'r4' with the
+ * instruction.
+ */
+void patch_imm32_load_insns(unsigned int val, kprobe_opcode_t *addr)
+{
+	/* addis r4,0,(insn)@h */
+	*addr++ = PPC_INST_ADDIS | ___PPC_RT(4) |
+		  ((val >> 16) & 0xffff);
+
+	/* ori r4,r4,(insn)@l */
+	*addr = PPC_INST_ORI | ___PPC_RA(4) | ___PPC_RS(4) |
+		(val & 0xffff);
+}
+
+/*
+ * Generate instructions to load provided immediate 64-bit value
+ * to register 'r3' and patch these instructions at 'addr'.
+ */
+void patch_imm64_load_insns(unsigned long val, kprobe_opcode_t *addr)
+{
+	/* lis r3,(op)@highest */
+	*addr++ = PPC_INST_ADDIS | ___PPC_RT(3) |
+		  ((val >> 48) & 0xffff);
+
+	/* ori r3,r3,(op)@higher */
+	*addr++ = PPC_INST_ORI | ___PPC_RA(3) | ___PPC_RS(3) |
+		  ((val >> 32) & 0xffff);
+
+	/* rldicr r3,r3,32,31 */
+	*addr++ = PPC_INST_RLDICR | ___PPC_RA(3) | ___PPC_RS(3) |
+		  __PPC_SH64(32) | __PPC_ME64(31);
+
+	/* oris r3,r3,(op)@h */
+	*addr++ = PPC_INST_ORIS | ___PPC_RA(3) | ___PPC_RS(3) |
+		  ((val >> 16) & 0xffff);
+
+	/* ori r3,r3,(op)@l */
+	*addr = PPC_INST_ORI | ___PPC_RA(3) | ___PPC_RS(3) |
+		(val & 0xffff);
+}
+
+int arch_prepare_optimized_kprobe(struct optimized_kprobe *op, struct kprobe *p)
+{
+	kprobe_opcode_t *buff, branch_op_callback, branch_emulate_step;
+	kprobe_opcode_t *op_callback_addr, *emulate_step_addr;
+	long b_offset;
+	unsigned long nip;
+
+	kprobe_ppc_optinsn_slots.insn_size = MAX_OPTINSN_SIZE;
+
+	nip = can_optimize(p);
+	if (!nip)
+		return -EILSEQ;
+
+	/* Allocate instruction slot for detour buffer */
+	buff = get_ppc_optinsn_slot();
+	if (!buff)
+		return -ENOMEM;
+
+	/*
+	 * OPTPROBE uses 'b' instruction to branch to optinsn.insn.
+	 *
+	 * The target address has to be relatively nearby, to permit use
+	 * of branch instruction in powerpc, because the address is specified
+	 * in an immediate field in the instruction opcode itself, ie 24 bits
+	 * in the opcode specify the address. Therefore the address should
+	 * be within 32MB on either side of the current instruction.
+	 */
+	b_offset = (unsigned long)buff - (unsigned long)p->addr;
+	if (!is_offset_in_branch_range(b_offset))
+		goto error;
+
+	/* Check if the return address is also within 32MB range */
+	b_offset = (unsigned long)(buff + TMPL_RET_IDX) -
+			(unsigned long)nip;
+	if (!is_offset_in_branch_range(b_offset))
+		goto error;
+
+	/* Setup template */
+	memcpy(buff, optprobe_template_entry,
+			TMPL_END_IDX * sizeof(kprobe_opcode_t));
+
+	/*
+	 * Fixup the template with instructions to:
+	 * 1. load the address of the actual probepoint
+	 */
+	patch_imm64_load_insns((unsigned long)op, buff + TMPL_OP_IDX);
+
+	/*
+	 * 2. branch to optimized_callback() and emulate_step()
+	 */
+	kprobe_lookup_name("optimized_callback", op_callback_addr);
+	kprobe_lookup_name("emulate_step", emulate_step_addr);
+	if (!op_callback_addr || !emulate_step_addr) {
+		WARN(1, "kprobe_lookup_name() failed\n");
+		goto error;
+	}
+
+	branch_op_callback = create_branch((unsigned int *)buff + TMPL_CALL_HDLR_IDX,
+				(unsigned long)op_callback_addr,
+				BRANCH_SET_LINK);
+
+	branch_emulate_step = create_branch((unsigned int *)buff + TMPL_EMULATE_IDX,
+				(unsigned long)emulate_step_addr,
+				BRANCH_SET_LINK);
+
+	if (!branch_op_callback || !branch_emulate_step)
+		goto error;
+
+	buff[TMPL_CALL_HDLR_IDX] = branch_op_callback;
+	buff[TMPL_EMULATE_IDX] = branch_emulate_step;
+
+	/*
+	 * 3. load instruction to be emulated into relevant register, and
+	 */
+	patch_imm32_load_insns(*p->ainsn.insn, buff + TMPL_INSN_IDX);
+
+	/*
+	 * 4. branch back from trampoline
+	 */
+	buff[TMPL_RET_IDX] = create_branch((unsigned int *)buff + TMPL_RET_IDX,
+				(unsigned long)nip, 0);
+
+	flush_icache_range((unsigned long)buff,
+			   (unsigned long)(&buff[TMPL_END_IDX]));
+
+	op->optinsn.insn = buff;
+
+	return 0;
+
+error:
+	free_ppc_optinsn_slot(buff, 0);
+	return -ERANGE;
+
+}
+
+int arch_prepared_optinsn(struct arch_optimized_insn *optinsn)
+{
+	return optinsn->insn != NULL;
+}
+
+/*
+ * On powerpc, Optprobes always replaces one instruction (4 bytes
+ * aligned and 4 bytes long). It is impossible to encounter another
+ * kprobe in this address range. So always return 0.
+ */
+int arch_check_optimized_kprobe(struct optimized_kprobe *op)
+{
+	return 0;
+}
+
+void arch_optimize_kprobes(struct list_head *oplist)
+{
+	struct optimized_kprobe *op;
+	struct optimized_kprobe *tmp;
+
+	list_for_each_entry_safe(op, tmp, oplist, list) {
+		/*
+		 * Backup instructions which will be replaced
+		 * by jump address
+		 */
+		memcpy(op->optinsn.copied_insn, op->kp.addr,
+					       RELATIVEJUMP_SIZE);
+		patch_instruction(op->kp.addr,
+			create_branch((unsigned int *)op->kp.addr,
+				      (unsigned long)op->optinsn.insn, 0));
+		list_del_init(&op->list);
+	}
+}
+
+void arch_unoptimize_kprobe(struct optimized_kprobe *op)
+{
+	arch_arm_kprobe(&op->kp);
+}
+
+void arch_unoptimize_kprobes(struct list_head *oplist,
+			     struct list_head *done_list)
+{
+	struct optimized_kprobe *op;
+	struct optimized_kprobe *tmp;
+
+	list_for_each_entry_safe(op, tmp, oplist, list) {
+		arch_unoptimize_kprobe(op);
+		list_move(&op->list, done_list);
+	}
+}
+
+int arch_within_optimized_kprobe(struct optimized_kprobe *op,
+				 unsigned long addr)
+{
+	return ((unsigned long)op->kp.addr <= addr &&
+		(unsigned long)op->kp.addr + RELATIVEJUMP_SIZE > addr);
+}