Adding upstream version 6.1.76.upstream/6.1.76

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 304 insertions, 0 deletions

diff --git a/arch/powerpc/kernel/optprobes.c b/arch/powerpc/kernel/optprobes.c
new file mode 100644
index 000000000..3b1c2236c
--- /dev/null
+++ b/arch/powerpc/kernel/optprobes.c
@@ -0,0 +1,304 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Code for Kernel probes Jump optimization.
+ *
+ * Copyright 2017, Anju T, IBM Corp.
+ */
+
+#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>
+#include <asm/inst.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)
+
+static bool insn_page_in_use;
+
+void *alloc_optinsn_page(void)
+{
+	if (insn_page_in_use)
+		return NULL;
+	insn_page_in_use = true;
+	return &optinsn_slot;
+}
+
+void free_optinsn_page(void *page)
+{
+	insn_page_in_use = false;
+}
+
+/*
+ * 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;
+	unsigned long addr = (unsigned long)p->addr;
+
+	/*
+	 * 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 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(addr))
+		return 0;
+
+	memset(&regs, 0, sizeof(struct pt_regs));
+	regs.nip = 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(ppc_inst_read(p->ainsn.insn)) &&
+	    analyse_instr(&op, &regs, ppc_inst_read(p->ainsn.insn)) == 1) {
+		emulate_update_regs(&regs, &op);
+		nip = regs.nip;
+	}
+
+	return nip;
+}
+
+static void optimized_callback(struct optimized_kprobe *op,
+			       struct pt_regs *regs)
+{
+	/* This is possible if op is under delayed unoptimizing */
+	if (kprobe_disabled(&op->kp))
+		return;
+
+	preempt_disable();
+
+	if (kprobe_running()) {
+		kprobes_inc_nmissed_count(&op->kp);
+	} else {
+		__this_cpu_write(current_kprobe, &op->kp);
+		regs_set_return_ip(regs, (unsigned long)op->kp.addr);
+		get_kprobe_ctlblk()->kprobe_status = KPROBE_HIT_ACTIVE;
+		opt_pre_handler(&op->kp, regs);
+		__this_cpu_write(current_kprobe, NULL);
+	}
+
+	preempt_enable_no_resched();
+}
+NOKPROBE_SYMBOL(optimized_callback);
+
+void arch_remove_optimized_kprobe(struct optimized_kprobe *op)
+{
+	if (op->optinsn.insn) {
+		free_optinsn_slot(op->optinsn.insn, 1);
+		op->optinsn.insn = NULL;
+	}
+}
+
+static void patch_imm32_load_insns(unsigned long val, int reg, kprobe_opcode_t *addr)
+{
+	patch_instruction(addr++, ppc_inst(PPC_RAW_LIS(reg, PPC_HI(val))));
+	patch_instruction(addr, ppc_inst(PPC_RAW_ORI(reg, reg, PPC_LO(val))));
+}
+
+/*
+ * Generate instructions to load provided immediate 64-bit value
+ * to register 'reg' and patch these instructions at 'addr'.
+ */
+static void patch_imm64_load_insns(unsigned long long val, int reg, kprobe_opcode_t *addr)
+{
+	patch_instruction(addr++, ppc_inst(PPC_RAW_LIS(reg, PPC_HIGHEST(val))));
+	patch_instruction(addr++, ppc_inst(PPC_RAW_ORI(reg, reg, PPC_HIGHER(val))));
+	patch_instruction(addr++, ppc_inst(PPC_RAW_SLDI(reg, reg, 32)));
+	patch_instruction(addr++, ppc_inst(PPC_RAW_ORIS(reg, reg, PPC_HI(val))));
+	patch_instruction(addr, ppc_inst(PPC_RAW_ORI(reg, reg, PPC_LO(val))));
+}
+
+static void patch_imm_load_insns(unsigned long val, int reg, kprobe_opcode_t *addr)
+{
+	if (IS_ENABLED(CONFIG_PPC64))
+		patch_imm64_load_insns(val, reg, addr);
+	else
+		patch_imm32_load_insns(val, reg, addr);
+}
+
+int arch_prepare_optimized_kprobe(struct optimized_kprobe *op, struct kprobe *p)
+{
+	ppc_inst_t branch_op_callback, branch_emulate_step, temp;
+	unsigned long op_callback_addr, emulate_step_addr;
+	kprobe_opcode_t *buff;
+	long b_offset;
+	unsigned long nip, size;
+	int rc, i;
+
+	nip = can_optimize(p);
+	if (!nip)
+		return -EILSEQ;
+
+	/* Allocate instruction slot for detour buffer */
+	buff = get_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) - nip;
+	if (!is_offset_in_branch_range(b_offset))
+		goto error;
+
+	/* Setup template */
+	/* We can optimize this via patch_instruction_window later */
+	size = (TMPL_END_IDX * sizeof(kprobe_opcode_t)) / sizeof(int);
+	pr_devel("Copying template to %p, size %lu\n", buff, size);
+	for (i = 0; i < size; i++) {
+		rc = patch_instruction(buff + i, ppc_inst(*(optprobe_template_entry + i)));
+		if (rc < 0)
+			goto error;
+	}
+
+	/*
+	 * Fixup the template with instructions to:
+	 * 1. load the address of the actual probepoint
+	 */
+	patch_imm_load_insns((unsigned long)op, 3, buff + TMPL_OP_IDX);
+
+	/*
+	 * 2. branch to optimized_callback() and emulate_step()
+	 */
+	op_callback_addr = ppc_kallsyms_lookup_name("optimized_callback");
+	emulate_step_addr = ppc_kallsyms_lookup_name("emulate_step");
+	if (!op_callback_addr || !emulate_step_addr) {
+		WARN(1, "Unable to lookup optimized_callback()/emulate_step()\n");
+		goto error;
+	}
+
+	rc = create_branch(&branch_op_callback, buff + TMPL_CALL_HDLR_IDX,
+			   op_callback_addr, BRANCH_SET_LINK);
+
+	rc |= create_branch(&branch_emulate_step, buff + TMPL_EMULATE_IDX,
+			    emulate_step_addr, BRANCH_SET_LINK);
+
+	if (rc)
+		goto error;
+
+	patch_instruction(buff + TMPL_CALL_HDLR_IDX, branch_op_callback);
+	patch_instruction(buff + TMPL_EMULATE_IDX, branch_emulate_step);
+
+	/*
+	 * 3. load instruction to be emulated into relevant register, and
+	 */
+	temp = ppc_inst_read(p->ainsn.insn);
+	patch_imm_load_insns(ppc_inst_as_ulong(temp), 4, buff + TMPL_INSN_IDX);
+
+	/*
+	 * 4. branch back from trampoline
+	 */
+	patch_branch(buff + TMPL_RET_IDX, nip, 0);
+
+	flush_icache_range((unsigned long)buff, (unsigned long)(&buff[TMPL_END_IDX]));
+
+	op->optinsn.insn = buff;
+
+	return 0;
+
+error:
+	free_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)
+{
+	ppc_inst_t instr;
+	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);
+		create_branch(&instr, op->kp.addr, (unsigned long)op->optinsn.insn, 0);
+		patch_instruction(op->kp.addr, instr);
+		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, kprobe_opcode_t *addr)
+{
+	return (op->kp.addr <= addr &&
+		op->kp.addr + (RELATIVEJUMP_SIZE / sizeof(kprobe_opcode_t)) > addr);
+}