MIPS: Add uprobes support.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/kernel/uprobes.c b/arch/mips/kernel/uprobes.c
new file mode 100644
index 0000000..8452d93
--- /dev/null
+++ b/arch/mips/kernel/uprobes.c
@@ -0,0 +1,341 @@
+#include <linux/highmem.h>
+#include <linux/kdebug.h>
+#include <linux/types.h>
+#include <linux/notifier.h>
+#include <linux/sched.h>
+#include <linux/uprobes.h>
+
+#include <asm/branch.h>
+#include <asm/cpu-features.h>
+#include <asm/ptrace.h>
+#include <asm/inst.h>
+
+static inline int insn_has_delay_slot(const union mips_instruction insn)
+{
+ switch (insn.i_format.opcode) {
+ /*
+ * jr and jalr are in r_format format.
+ */
+ case spec_op:
+ switch (insn.r_format.func) {
+ case jalr_op:
+ case jr_op:
+ return 1;
+ }
+ break;
+
+ /*
+ * This group contains:
+ * bltz_op, bgez_op, bltzl_op, bgezl_op,
+ * bltzal_op, bgezal_op, bltzall_op, bgezall_op.
+ */
+ case bcond_op:
+ switch (insn.i_format.rt) {
+ case bltz_op:
+ case bltzl_op:
+ case bgez_op:
+ case bgezl_op:
+ case bltzal_op:
+ case bltzall_op:
+ case bgezal_op:
+ case bgezall_op:
+ case bposge32_op:
+ return 1;
+ }
+ break;
+
+ /*
+ * These are unconditional and in j_format.
+ */
+ case jal_op:
+ case j_op:
+ case beq_op:
+ case beql_op:
+ case bne_op:
+ case bnel_op:
+ case blez_op: /* not really i_format */
+ case blezl_op:
+ case bgtz_op:
+ case bgtzl_op:
+ return 1;
+
+ /*
+ * And now the FPA/cp1 branch instructions.
+ */
+ case cop1_op:
+#ifdef CONFIG_CPU_CAVIUM_OCTEON
+ case lwc2_op: /* This is bbit0 on Octeon */
+ case ldc2_op: /* This is bbit032 on Octeon */
+ case swc2_op: /* This is bbit1 on Octeon */
+ case sdc2_op: /* This is bbit132 on Octeon */
+#endif
+ return 1;
+ }
+
+ return 0;
+}
+
+/**
+ * arch_uprobe_analyze_insn - instruction analysis including validity and fixups.
+ * @mm: the probed address space.
+ * @arch_uprobe: the probepoint information.
+ * @addr: virtual address at which to install the probepoint
+ * Return 0 on success or a -ve number on error.
+ */
+int arch_uprobe_analyze_insn(struct arch_uprobe *aup,
+ struct mm_struct *mm, unsigned long addr)
+{
+ union mips_instruction inst;
+
+ /*
+ * For the time being this also blocks attempts to use uprobes with
+ * MIPS16 and microMIPS.
+ */
+ if (addr & 0x03)
+ return -EINVAL;
+
+ inst.word = aup->insn[0];
+ aup->ixol[0] = aup->insn[insn_has_delay_slot(inst)];
+ aup->ixol[1] = UPROBE_BRK_UPROBE_XOL; /* NOP */
+
+ return 0;
+}
+
+/**
+ * is_trap_insn - check if the instruction is a trap variant
+ * @insn: instruction to be checked.
+ * Returns true if @insn is a trap variant.
+ *
+ * This definition overrides the weak definition in kernel/events/uprobes.c.
+ * and is needed for the case where an architecture has multiple trap
+ * instructions (like PowerPC or MIPS). We treat BREAK just like the more
+ * modern conditional trap instructions.
+ */
+bool is_trap_insn(uprobe_opcode_t *insn)
+{
+ union mips_instruction inst;
+
+ inst.word = *insn;
+
+ switch (inst.i_format.opcode) {
+ case spec_op:
+ switch (inst.r_format.func) {
+ case break_op:
+ case teq_op:
+ case tge_op:
+ case tgeu_op:
+ case tlt_op:
+ case tltu_op:
+ case tne_op:
+ return 1;
+ }
+ break;
+
+ case bcond_op: /* Yes, really ... */
+ switch (inst.u_format.rt) {
+ case teqi_op:
+ case tgei_op:
+ case tgeiu_op:
+ case tlti_op:
+ case tltiu_op:
+ case tnei_op:
+ return 1;
+ }
+ break;
+ }
+
+ return 0;
+}
+
+#define UPROBE_TRAP_NR ULONG_MAX
+
+/*
+ * arch_uprobe_pre_xol - prepare to execute out of line.
+ * @auprobe: the probepoint information.
+ * @regs: reflects the saved user state of current task.
+ */
+int arch_uprobe_pre_xol(struct arch_uprobe *aup, struct pt_regs *regs)
+{
+ struct uprobe_task *utask = current->utask;
+ union mips_instruction insn;
+
+ /*
+ * Now find the EPC where to resume after the breakpoint has been
+ * dealt with. This may require emulation of a branch.
+ */
+ aup->resume_epc = regs->cp0_epc + 4;
+ if (insn_has_delay_slot((union mips_instruction) aup->insn[0])) {
+ unsigned long epc;
+
+ epc = regs->cp0_epc;
+ __compute_return_epc_for_insn(regs, insn);
+ aup->resume_epc = regs->cp0_epc;
+ }
+
+ utask->autask.saved_trap_nr = current->thread.trap_nr;
+ current->thread.trap_nr = UPROBE_TRAP_NR;
+ regs->cp0_epc = current->utask->xol_vaddr;
+
+ return 0;
+}
+
+int arch_uprobe_post_xol(struct arch_uprobe *aup, struct pt_regs *regs)
+{
+ struct uprobe_task *utask = current->utask;
+
+ current->thread.trap_nr = utask->autask.saved_trap_nr;
+ regs->cp0_epc = aup->resume_epc;
+
+ return 0;
+}
+
+/*
+ * If xol insn itself traps and generates a signal(Say,
+ * SIGILL/SIGSEGV/etc), then detect the case where a singlestepped
+ * instruction jumps back to its own address. It is assumed that anything
+ * like do_page_fault/do_trap/etc sets thread.trap_nr != -1.
+ *
+ * arch_uprobe_pre_xol/arch_uprobe_post_xol save/restore thread.trap_nr,
+ * arch_uprobe_xol_was_trapped() simply checks that ->trap_nr is not equal to
+ * UPROBE_TRAP_NR == -1 set by arch_uprobe_pre_xol().
+ */
+bool arch_uprobe_xol_was_trapped(struct task_struct *tsk)
+{
+ if (tsk->thread.trap_nr != UPROBE_TRAP_NR)
+ return true;
+
+ return false;
+}
+
+int arch_uprobe_exception_notify(struct notifier_block *self,
+ unsigned long val, void *data)
+{
+ struct die_args *args = data;
+ struct pt_regs *regs = args->regs;
+
+ /* regs == NULL is a kernel bug */
+ if (WARN_ON(!regs))
+ return NOTIFY_DONE;
+
+ /* We are only interested in userspace traps */
+ if (!user_mode(regs))
+ return NOTIFY_DONE;
+
+ switch (val) {
+ case DIE_BREAK:
+ if (uprobe_pre_sstep_notifier(regs))
+ return NOTIFY_STOP;
+ break;
+ case DIE_UPROBE_XOL:
+ if (uprobe_post_sstep_notifier(regs))
+ return NOTIFY_STOP;
+ default:
+ break;
+ }
+
+ return 0;
+}
+
+/*
+ * This function gets called when XOL instruction either gets trapped or
+ * the thread has a fatal signal. Reset the instruction pointer to its
+ * probed address for the potential restart or for post mortem analysis.
+ */
+void arch_uprobe_abort_xol(struct arch_uprobe *aup,
+ struct pt_regs *regs)
+{
+ struct uprobe_task *utask = current->utask;
+
+ instruction_pointer_set(regs, utask->vaddr);
+}
+
+unsigned long arch_uretprobe_hijack_return_addr(
+ unsigned long trampoline_vaddr, struct pt_regs *regs)
+{
+ unsigned long ra;
+
+ ra = regs->regs[31];
+
+ /* Replace the return address with the trampoline address */
+ regs->regs[31] = ra;
+
+ return ra;
+}
+
+/**
+ * set_swbp - store breakpoint at a given address.
+ * @auprobe: arch specific probepoint information.
+ * @mm: the probed process address space.
+ * @vaddr: the virtual address to insert the opcode.
+ *
+ * For mm @mm, store the breakpoint instruction at @vaddr.
+ * Return 0 (success) or a negative errno.
+ *
+ * This version overrides the weak version in kernel/events/uprobes.c.
+ * It is required to handle MIPS16 and microMIPS.
+ */
+int __weak set_swbp(struct arch_uprobe *auprobe, struct mm_struct *mm,
+ unsigned long vaddr)
+{
+ return uprobe_write_opcode(mm, vaddr, UPROBE_SWBP_INSN);
+}
+
+/**
+ * set_orig_insn - Restore the original instruction.
+ * @mm: the probed process address space.
+ * @auprobe: arch specific probepoint information.
+ * @vaddr: the virtual address to insert the opcode.
+ *
+ * For mm @mm, restore the original opcode (opcode) at @vaddr.
+ * Return 0 (success) or a negative errno.
+ *
+ * This overrides the weak version in kernel/events/uprobes.c.
+ */
+int set_orig_insn(struct arch_uprobe *auprobe, struct mm_struct *mm,
+ unsigned long vaddr)
+{
+ return uprobe_write_opcode(mm, vaddr,
+ *(uprobe_opcode_t *)&auprobe->orig_inst[0].word);
+}
+
+void __weak arch_uprobe_copy_ixol(struct page *page, unsigned long vaddr,
+ void *src, unsigned long len)
+{
+ void *kaddr;
+
+ /* Initialize the slot */
+ kaddr = kmap_atomic(page);
+ memcpy(kaddr + (vaddr & ~PAGE_MASK), src, len);
+ kunmap_atomic(kaddr);
+
+ /*
+ * The MIPS version of flush_icache_range will operate safely on
+ * user space addresses and more importantly, it doesn't require a
+ * VMA argument.
+ */
+ flush_icache_range(vaddr, vaddr + len);
+}
+
+/**
+ * uprobe_get_swbp_addr - compute address of swbp given post-swbp regs
+ * @regs: Reflects the saved state of the task after it has hit a breakpoint
+ * instruction.
+ * Return the address of the breakpoint instruction.
+ *
+ * This overrides the weak version in kernel/events/uprobes.c.
+ */
+unsigned long uprobe_get_swbp_addr(struct pt_regs *regs)
+{
+ return instruction_pointer(regs);
+}
+
+/*
+ * See if the instruction can be emulated.
+ * Returns true if instruction was emulated, false otherwise.
+ *
+ * For now we always emulate so this function just returns 0.
+ */
+bool arch_uprobe_skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs)
+{
+ return 0;
+}