--- /dev/null
+/*
+ * Copyright 2010 Tilera Corporation. All Rights Reserved.
+ *
+ * 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, version 2.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
+ * NON INFRINGEMENT. See the GNU General Public License for
+ * more details.
+ *
+ * A code-rewriter that enables instruction single-stepping.
+ */
+
+#include <linux/smp.h>
+#include <linux/ptrace.h>
+#include <linux/slab.h>
+#include <linux/thread_info.h>
+#include <linux/uaccess.h>
+#include <linux/mman.h>
+#include <linux/types.h>
+#include <linux/err.h>
+#include <linux/prctl.h>
+#include <linux/context_tracking.h>
+#include <asm/cacheflush.h>
+#include <asm/traps.h>
+#include <asm/uaccess.h>
+#include <asm/unaligned.h>
+#include <arch/abi.h>
+#include <arch/spr_def.h>
+#include <arch/opcode.h>
+
+
+#ifndef __tilegx__ /* Hardware support for single step unavailable. */
+
+#define signExtend17(val) sign_extend((val), 17)
+#define TILE_X1_MASK (0xffffffffULL << 31)
+
+enum mem_op {
+ MEMOP_NONE,
+ MEMOP_LOAD,
+ MEMOP_STORE,
+ MEMOP_LOAD_POSTINCR,
+ MEMOP_STORE_POSTINCR
+};
+
+static inline tilepro_bundle_bits set_BrOff_X1(tilepro_bundle_bits n,
+ s32 offset)
+{
+ tilepro_bundle_bits result;
+
+ /* mask out the old offset */
+ tilepro_bundle_bits mask = create_BrOff_X1(-1);
+ result = n & (~mask);
+
+ /* or in the new offset */
+ result |= create_BrOff_X1(offset);
+
+ return result;
+}
+
+static inline tilepro_bundle_bits move_X1(tilepro_bundle_bits n, int dest,
+ int src)
+{
+ tilepro_bundle_bits result;
+ tilepro_bundle_bits op;
+
+ result = n & (~TILE_X1_MASK);
+
+ op = create_Opcode_X1(SPECIAL_0_OPCODE_X1) |
+ create_RRROpcodeExtension_X1(OR_SPECIAL_0_OPCODE_X1) |
+ create_Dest_X1(dest) |
+ create_SrcB_X1(TREG_ZERO) |
+ create_SrcA_X1(src) ;
+
+ result |= op;
+ return result;
+}
+
+static inline tilepro_bundle_bits nop_X1(tilepro_bundle_bits n)
+{
+ return move_X1(n, TREG_ZERO, TREG_ZERO);
+}
+
+static inline tilepro_bundle_bits addi_X1(
+ tilepro_bundle_bits n, int dest, int src, int imm)
+{
+ n &= ~TILE_X1_MASK;
+
+ n |= (create_SrcA_X1(src) |
+ create_Dest_X1(dest) |
+ create_Imm8_X1(imm) |
+ create_S_X1(0) |
+ create_Opcode_X1(IMM_0_OPCODE_X1) |
+ create_ImmOpcodeExtension_X1(ADDI_IMM_0_OPCODE_X1));
+
+ return n;
+}
+
+static tilepro_bundle_bits rewrite_load_store_unaligned(
+ struct single_step_state *state,
+ tilepro_bundle_bits bundle,
+ struct pt_regs *regs,
+ enum mem_op mem_op,
+ int size, int sign_ext)
+{
+ unsigned char __user *addr;
+ int val_reg, addr_reg, err, val;
+ int align_ctl;
+
+ align_ctl = unaligned_fixup;
+ switch (task_thread_info(current)->align_ctl) {
+ case PR_UNALIGN_NOPRINT:
+ align_ctl = 1;
+ break;
+ case PR_UNALIGN_SIGBUS:
+ align_ctl = 0;
+ break;
+ }
+
+ /* Get address and value registers */
+ if (bundle & TILEPRO_BUNDLE_Y_ENCODING_MASK) {
+ addr_reg = get_SrcA_Y2(bundle);
+ val_reg = get_SrcBDest_Y2(bundle);
+ } else if (mem_op == MEMOP_LOAD || mem_op == MEMOP_LOAD_POSTINCR) {
+ addr_reg = get_SrcA_X1(bundle);
+ val_reg = get_Dest_X1(bundle);
+ } else {
+ addr_reg = get_SrcA_X1(bundle);
+ val_reg = get_SrcB_X1(bundle);
+ }
+
+ /*
+ * If registers are not GPRs, don't try to handle it.
+ *
+ * FIXME: we could handle non-GPR loads by getting the real value
+ * from memory, writing it to the single step buffer, using a
+ * temp_reg to hold a pointer to that memory, then executing that
+ * instruction and resetting temp_reg. For non-GPR stores, it's a
+ * little trickier; we could use the single step buffer for that
+ * too, but we'd have to add some more state bits so that we could
+ * call back in here to copy that value to the real target. For
+ * now, we just handle the simple case.
+ */
+ if ((val_reg >= PTREGS_NR_GPRS &&
+ (val_reg != TREG_ZERO ||
+ mem_op == MEMOP_LOAD ||
+ mem_op == MEMOP_LOAD_POSTINCR)) ||
+ addr_reg >= PTREGS_NR_GPRS)
+ return bundle;
+
+ /* If it's aligned, don't handle it specially */
+ addr = (void __user *)regs->regs[addr_reg];
+ if (((unsigned long)addr % size) == 0)
+ return bundle;
+
+ /*
+ * Return SIGBUS with the unaligned address, if requested.
+ * Note that we return SIGBUS even for completely invalid addresses
+ * as long as they are in fact unaligned; this matches what the
+ * tilepro hardware would be doing, if it could provide us with the
+ * actual bad address in an SPR, which it doesn't.
+ */
+ if (align_ctl == 0) {
+ siginfo_t info = {
+ .si_signo = SIGBUS,
+ .si_code = BUS_ADRALN,
+ .si_addr = addr
+ };
+ trace_unhandled_signal("unaligned trap", regs,
+ (unsigned long)addr, SIGBUS);
+ force_sig_info(info.si_signo, &info, current);
+ return (tilepro_bundle_bits) 0;
+ }
+
+ /* Handle unaligned load/store */
+ if (mem_op == MEMOP_LOAD || mem_op == MEMOP_LOAD_POSTINCR) {
+ unsigned short val_16;
+ switch (size) {
+ case 2:
+ err = copy_from_user(&val_16, addr, sizeof(val_16));
+ val = sign_ext ? ((short)val_16) : val_16;
+ break;
+ case 4:
+ err = copy_from_user(&val, addr, sizeof(val));
+ break;
+ default:
+ BUG();
+ }
+ if (err == 0) {
+ state->update_reg = val_reg;
+ state->update_value = val;
+ state->update = 1;
+ }
+ } else {
+ unsigned short val_16;
+ val = (val_reg == TREG_ZERO) ? 0 : regs->regs[val_reg];
+ switch (size) {
+ case 2:
+ val_16 = val;
+ err = copy_to_user(addr, &val_16, sizeof(val_16));
+ break;
+ case 4:
+ err = copy_to_user(addr, &val, sizeof(val));
+ break;
+ default:
+ BUG();
+ }
+ }
+
+ if (err) {
+ siginfo_t info = {
+ .si_signo = SIGBUS,
+ .si_code = BUS_ADRALN,
+ .si_addr = addr
+ };
+ trace_unhandled_signal("bad address for unaligned fixup", regs,
+ (unsigned long)addr, SIGBUS);
+ force_sig_info(info.si_signo, &info, current);
+ return (tilepro_bundle_bits) 0;
+ }
+
+ if (unaligned_printk || unaligned_fixup_count == 0) {
+ pr_info("Process %d/%s: PC %#lx: Fixup of unaligned %s at %#lx\n",
+ current->pid, current->comm, regs->pc,
+ mem_op == MEMOP_LOAD || mem_op == MEMOP_LOAD_POSTINCR ?
+ "load" : "store",
+ (unsigned long)addr);
+ if (!unaligned_printk) {
+#define P pr_info
+P("\n");
+P("Unaligned fixups in the kernel will slow your application considerably.\n");
+P("To find them, write a \"1\" to /proc/sys/tile/unaligned_fixup/printk,\n");
+P("which requests the kernel show all unaligned fixups, or write a \"0\"\n");
+P("to /proc/sys/tile/unaligned_fixup/enabled, in which case each unaligned\n");
+P("access will become a SIGBUS you can debug. No further warnings will be\n");
+P("shown so as to avoid additional slowdown, but you can track the number\n");
+P("of fixups performed via /proc/sys/tile/unaligned_fixup/count.\n");
+P("Use the tile-addr2line command (see \"info addr2line\") to decode PCs.\n");
+P("\n");
+#undef P
+ }
+ }
+ ++unaligned_fixup_count;
+
+ if (bundle & TILEPRO_BUNDLE_Y_ENCODING_MASK) {
+ /* Convert the Y2 instruction to a prefetch. */
+ bundle &= ~(create_SrcBDest_Y2(-1) |
+ create_Opcode_Y2(-1));
+ bundle |= (create_SrcBDest_Y2(TREG_ZERO) |
+ create_Opcode_Y2(LW_OPCODE_Y2));
+ /* Replace the load postincr with an addi */
+ } else if (mem_op == MEMOP_LOAD_POSTINCR) {
+ bundle = addi_X1(bundle, addr_reg, addr_reg,
+ get_Imm8_X1(bundle));
+ /* Replace the store postincr with an addi */
+ } else if (mem_op == MEMOP_STORE_POSTINCR) {
+ bundle = addi_X1(bundle, addr_reg, addr_reg,
+ get_Dest_Imm8_X1(bundle));
+ } else {
+ /* Convert the X1 instruction to a nop. */
+ bundle &= ~(create_Opcode_X1(-1) |
+ create_UnShOpcodeExtension_X1(-1) |
+ create_UnOpcodeExtension_X1(-1));
+ bundle |= (create_Opcode_X1(SHUN_0_OPCODE_X1) |
+ create_UnShOpcodeExtension_X1(
+ UN_0_SHUN_0_OPCODE_X1) |
+ create_UnOpcodeExtension_X1(
+ NOP_UN_0_SHUN_0_OPCODE_X1));
+ }
+
+ return bundle;
+}
+
+/*
+ * Called after execve() has started the new image. This allows us
+ * to reset the info state. Note that the the mmap'ed memory, if there
+ * was any, has already been unmapped by the exec.
+ */
+void single_step_execve(void)
+{
+ struct thread_info *ti = current_thread_info();
+ kfree(ti->step_state);
+ ti->step_state = NULL;
+}
+
+/*
+ * single_step_once() - entry point when single stepping has been triggered.
+ * @regs: The machine register state
+ *
+ * When we arrive at this routine via a trampoline, the single step
+ * engine copies the executing bundle to the single step buffer.
+ * If the instruction is a condition branch, then the target is
+ * reset to one past the next instruction. If the instruction
+ * sets the lr, then that is noted. If the instruction is a jump
+ * or call, then the new target pc is preserved and the current
+ * bundle instruction set to null.
+ *
+ * The necessary post-single-step rewriting information is stored in
+ * single_step_state-> We use data segment values because the
+ * stack will be rewound when we run the rewritten single-stepped
+ * instruction.
+ */
+void single_step_once(struct pt_regs *regs)
+{
+ extern tilepro_bundle_bits __single_step_ill_insn;
+ extern tilepro_bundle_bits __single_step_j_insn;
+ extern tilepro_bundle_bits __single_step_addli_insn;
+ extern tilepro_bundle_bits __single_step_auli_insn;
+ struct thread_info *info = (void *)current_thread_info();
+ struct single_step_state *state = info->step_state;
+ int is_single_step = test_ti_thread_flag(info, TIF_SINGLESTEP);
+ tilepro_bundle_bits __user *buffer, *pc;
+ tilepro_bundle_bits bundle;
+ int temp_reg;
+ int target_reg = TREG_LR;
+ int err;
+ enum mem_op mem_op = MEMOP_NONE;
+ int size = 0, sign_ext = 0; /* happy compiler */
+ int align_ctl;
+
+ align_ctl = unaligned_fixup;
+ switch (task_thread_info(current)->align_ctl) {
+ case PR_UNALIGN_NOPRINT:
+ align_ctl = 1;
+ break;
+ case PR_UNALIGN_SIGBUS:
+ align_ctl = 0;
+ break;
+ }
+
+ asm(
+" .pushsection .rodata.single_step\n"
+" .align 8\n"
+" .globl __single_step_ill_insn\n"
+"__single_step_ill_insn:\n"
+" ill\n"
+" .globl __single_step_addli_insn\n"
+"__single_step_addli_insn:\n"
+" { nop; addli r0, zero, 0 }\n"
+" .globl __single_step_auli_insn\n"
+"__single_step_auli_insn:\n"
+" { nop; auli r0, r0, 0 }\n"
+" .globl __single_step_j_insn\n"
+"__single_step_j_insn:\n"
+" j .\n"
+" .popsection\n"
+ );
+
+ /*
+ * Enable interrupts here to allow touching userspace and the like.
+ * The callers expect this: do_trap() already has interrupts
+ * enabled, and do_work_pending() handles functions that enable
+ * interrupts internally.
+ */
+ local_irq_enable();
+
+ if (state == NULL) {
+ /* allocate a page of writable, executable memory */
+ state = kmalloc(sizeof(struct single_step_state), GFP_KERNEL);
+ if (state == NULL) {
+ pr_err("Out of kernel memory trying to single-step\n");
+ return;
+ }
+
+ /* allocate a cache line of writable, executable memory */
+ buffer = (void __user *) vm_mmap(NULL, 0, 64,
+ PROT_EXEC | PROT_READ | PROT_WRITE,
+ MAP_PRIVATE | MAP_ANONYMOUS,
+ 0);
+
+ if (IS_ERR((void __force *)buffer)) {
+ kfree(state);
+ pr_err("Out of kernel pages trying to single-step\n");
+ return;
+ }
+
+ state->buffer = buffer;
+ state->is_enabled = 0;
+
+ info->step_state = state;
+
+ /* Validate our stored instruction patterns */
+ BUG_ON(get_Opcode_X1(__single_step_addli_insn) !=
+ ADDLI_OPCODE_X1);
+ BUG_ON(get_Opcode_X1(__single_step_auli_insn) !=
+ AULI_OPCODE_X1);
+ BUG_ON(get_SrcA_X1(__single_step_addli_insn) != TREG_ZERO);
+ BUG_ON(get_Dest_X1(__single_step_addli_insn) != 0);
+ BUG_ON(get_JOffLong_X1(__single_step_j_insn) != 0);
+ }
+
+ /*
+ * If we are returning from a syscall, we still haven't hit the
+ * "ill" for the swint1 instruction. So back the PC up to be
+ * pointing at the swint1, but we'll actually return directly
+ * back to the "ill" so we come back in via SIGILL as if we
+ * had "executed" the swint1 without ever being in kernel space.
+ */
+ if (regs->faultnum == INT_SWINT_1)
+ regs->pc -= 8;
+
+ pc = (tilepro_bundle_bits __user *)(regs->pc);
+ if (get_user(bundle, pc) != 0) {
+ pr_err("Couldn't read instruction at %p trying to step\n", pc);
+ return;
+ }
+
+ /* We'll follow the instruction with 2 ill op bundles */
+ state->orig_pc = (unsigned long)pc;
+ state->next_pc = (unsigned long)(pc + 1);
+ state->branch_next_pc = 0;
+ state->update = 0;
+
+ if (!(bundle & TILEPRO_BUNDLE_Y_ENCODING_MASK)) {
+ /* two wide, check for control flow */
+ int opcode = get_Opcode_X1(bundle);
+
+ switch (opcode) {
+ /* branches */
+ case BRANCH_OPCODE_X1:
+ {
+ s32 offset = signExtend17(get_BrOff_X1(bundle));
+
+ /*
+ * For branches, we use a rewriting trick to let the
+ * hardware evaluate whether the branch is taken or
+ * untaken. We record the target offset and then
+ * rewrite the branch instruction to target 1 insn
+ * ahead if the branch is taken. We then follow the
+ * rewritten branch with two bundles, each containing
+ * an "ill" instruction. The supervisor examines the
+ * pc after the single step code is executed, and if
+ * the pc is the first ill instruction, then the
+ * branch (if any) was not taken. If the pc is the
+ * second ill instruction, then the branch was
+ * taken. The new pc is computed for these cases, and
+ * inserted into the registers for the thread. If
+ * the pc is the start of the single step code, then
+ * an exception or interrupt was taken before the
+ * code started processing, and the same "original"
+ * pc is restored. This change, different from the
+ * original implementation, has the advantage of
+ * executing a single user instruction.
+ */
+ state->branch_next_pc = (unsigned long)(pc + offset);
+
+ /* rewrite branch offset to go forward one bundle */
+ bundle = set_BrOff_X1(bundle, 2);
+ }
+ break;
+
+ /* jumps */
+ case JALB_OPCODE_X1:
+ case JALF_OPCODE_X1:
+ state->update = 1;
+ state->next_pc =
+ (unsigned long) (pc + get_JOffLong_X1(bundle));
+ break;
+
+ case JB_OPCODE_X1:
+ case JF_OPCODE_X1:
+ state->next_pc =
+ (unsigned long) (pc + get_JOffLong_X1(bundle));
+ bundle = nop_X1(bundle);
+ break;
+
+ case SPECIAL_0_OPCODE_X1:
+ switch (get_RRROpcodeExtension_X1(bundle)) {
+ /* jump-register */
+ case JALRP_SPECIAL_0_OPCODE_X1:
+ case JALR_SPECIAL_0_OPCODE_X1:
+ state->update = 1;
+ state->next_pc =
+ regs->regs[get_SrcA_X1(bundle)];
+ break;
+
+ case JRP_SPECIAL_0_OPCODE_X1:
+ case JR_SPECIAL_0_OPCODE_X1:
+ state->next_pc =
+ regs->regs[get_SrcA_X1(bundle)];
+ bundle = nop_X1(bundle);
+ break;
+
+ case LNK_SPECIAL_0_OPCODE_X1:
+ state->update = 1;
+ target_reg = get_Dest_X1(bundle);
+ break;
+
+ /* stores */
+ case SH_SPECIAL_0_OPCODE_X1:
+ mem_op = MEMOP_STORE;
+ size = 2;
+ break;
+
+ case SW_SPECIAL_0_OPCODE_X1:
+ mem_op = MEMOP_STORE;
+ size = 4;
+ break;
+ }
+ break;
+
+ /* loads and iret */
+ case SHUN_0_OPCODE_X1:
+ if (get_UnShOpcodeExtension_X1(bundle) ==
+ UN_0_SHUN_0_OPCODE_X1) {
+ switch (get_UnOpcodeExtension_X1(bundle)) {
+ case LH_UN_0_SHUN_0_OPCODE_X1:
+ mem_op = MEMOP_LOAD;
+ size = 2;
+ sign_ext = 1;
+ break;
+
+ case LH_U_UN_0_SHUN_0_OPCODE_X1:
+ mem_op = MEMOP_LOAD;
+ size = 2;
+ sign_ext = 0;
+ break;
+
+ case LW_UN_0_SHUN_0_OPCODE_X1:
+ mem_op = MEMOP_LOAD;
+ size = 4;
+ break;
+
+ case IRET_UN_0_SHUN_0_OPCODE_X1:
+ {
+ unsigned long ex0_0 = __insn_mfspr(
+ SPR_EX_CONTEXT_0_0);
+ unsigned long ex0_1 = __insn_mfspr(
+ SPR_EX_CONTEXT_0_1);
+ /*
+ * Special-case it if we're iret'ing
+ * to PL0 again. Otherwise just let
+ * it run and it will generate SIGILL.
+ */
+ if (EX1_PL(ex0_1) == USER_PL) {
+ state->next_pc = ex0_0;
+ regs->ex1 = ex0_1;
+ bundle = nop_X1(bundle);
+ }
+ }
+ }
+ }
+ break;
+
+ /* postincrement operations */
+ case IMM_0_OPCODE_X1:
+ switch (get_ImmOpcodeExtension_X1(bundle)) {
+ case LWADD_IMM_0_OPCODE_X1:
+ mem_op = MEMOP_LOAD_POSTINCR;
+ size = 4;
+ break;
+
+ case LHADD_IMM_0_OPCODE_X1:
+ mem_op = MEMOP_LOAD_POSTINCR;
+ size = 2;
+ sign_ext = 1;
+ break;
+
+ case LHADD_U_IMM_0_OPCODE_X1:
+ mem_op = MEMOP_LOAD_POSTINCR;
+ size = 2;
+ sign_ext = 0;
+ break;
+
+ case SWADD_IMM_0_OPCODE_X1:
+ mem_op = MEMOP_STORE_POSTINCR;
+ size = 4;
+ break;
+
+ case SHADD_IMM_0_OPCODE_X1:
+ mem_op = MEMOP_STORE_POSTINCR;
+ size = 2;
+ break;
+
+ default:
+ break;
+ }
+ break;
+ }
+
+ if (state->update) {
+ /*
+ * Get an available register. We start with a
+ * bitmask with 1's for available registers.
+ * We truncate to the low 32 registers since
+ * we are guaranteed to have set bits in the
+ * low 32 bits, then use ctz to pick the first.
+ */
+ u32 mask = (u32) ~((1ULL << get_Dest_X0(bundle)) |
+ (1ULL << get_SrcA_X0(bundle)) |
+ (1ULL << get_SrcB_X0(bundle)) |
+ (1ULL << target_reg));
+ temp_reg = __builtin_ctz(mask);
+ state->update_reg = temp_reg;
+ state->update_value = regs->regs[temp_reg];
+ regs->regs[temp_reg] = (unsigned long) (pc+1);
+ regs->flags |= PT_FLAGS_RESTORE_REGS;
+ bundle = move_X1(bundle, target_reg, temp_reg);
+ }
+ } else {
+ int opcode = get_Opcode_Y2(bundle);
+
+ switch (opcode) {
+ /* loads */
+ case LH_OPCODE_Y2:
+ mem_op = MEMOP_LOAD;
+ size = 2;
+ sign_ext = 1;
+ break;
+
+ case LH_U_OPCODE_Y2:
+ mem_op = MEMOP_LOAD;
+ size = 2;
+ sign_ext = 0;
+ break;
+
+ case LW_OPCODE_Y2:
+ mem_op = MEMOP_LOAD;
+ size = 4;
+ break;
+
+ /* stores */
+ case SH_OPCODE_Y2:
+ mem_op = MEMOP_STORE;
+ size = 2;
+ break;
+
+ case SW_OPCODE_Y2:
+ mem_op = MEMOP_STORE;
+ size = 4;
+ break;
+ }
+ }
+
+ /*
+ * Check if we need to rewrite an unaligned load/store.
+ * Returning zero is a special value meaning we generated a signal.
+ */
+ if (mem_op != MEMOP_NONE && align_ctl >= 0) {
+ bundle = rewrite_load_store_unaligned(state, bundle, regs,
+ mem_op, size, sign_ext);
+ if (bundle == 0)
+ return;
+ }
+
+ /* write the bundle to our execution area */
+ buffer = state->buffer;
+ err = __put_user(bundle, buffer++);
+
+ /*
+ * If we're really single-stepping, we take an INT_ILL after.
+ * If we're just handling an unaligned access, we can just
+ * jump directly back to where we were in user code.
+ */
+ if (is_single_step) {
+ err |= __put_user(__single_step_ill_insn, buffer++);
+ err |= __put_user(__single_step_ill_insn, buffer++);
+ } else {
+ long delta;
+
+ if (state->update) {
+ /* We have some state to update; do it inline */
+ int ha16;
+ bundle = __single_step_addli_insn;
+ bundle |= create_Dest_X1(state->update_reg);
+ bundle |= create_Imm16_X1(state->update_value);
+ err |= __put_user(bundle, buffer++);
+ bundle = __single_step_auli_insn;
+ bundle |= create_Dest_X1(state->update_reg);
+ bundle |= create_SrcA_X1(state->update_reg);
+ ha16 = (state->update_value + 0x8000) >> 16;
+ bundle |= create_Imm16_X1(ha16);
+ err |= __put_user(bundle, buffer++);
+ state->update = 0;
+ }
+
+ /* End with a jump back to the next instruction */
+ delta = ((regs->pc + TILEPRO_BUNDLE_SIZE_IN_BYTES) -
+ (unsigned long)buffer) >>
+ TILEPRO_LOG2_BUNDLE_ALIGNMENT_IN_BYTES;
+ bundle = __single_step_j_insn;
+ bundle |= create_JOffLong_X1(delta);
+ err |= __put_user(bundle, buffer++);
+ }
+
+ if (err) {
+ pr_err("Fault when writing to single-step buffer\n");
+ return;
+ }
+
+ /*
+ * Flush the buffer.
+ * We do a local flush only, since this is a thread-specific buffer.
+ */
+ __flush_icache_range((unsigned long)state->buffer,
+ (unsigned long)buffer);
+
+ /* Indicate enabled */
+ state->is_enabled = is_single_step;
+ regs->pc = (unsigned long)state->buffer;
+
+ /* Fault immediately if we are coming back from a syscall. */
+ if (regs->faultnum == INT_SWINT_1)
+ regs->pc += 8;
+}
+
+#else
+
+static DEFINE_PER_CPU(unsigned long, ss_saved_pc);
+
+
+/*
+ * Called directly on the occasion of an interrupt.
+ *
+ * If the process doesn't have single step set, then we use this as an
+ * opportunity to turn single step off.
+ *
+ * It has been mentioned that we could conditionally turn off single stepping
+ * on each entry into the kernel and rely on single_step_once to turn it
+ * on for the processes that matter (as we already do), but this
+ * implementation is somewhat more efficient in that we muck with registers
+ * once on a bum interrupt rather than on every entry into the kernel.
+ *
+ * If SINGLE_STEP_CONTROL_K has CANCELED set, then an interrupt occurred,
+ * so we have to run through this process again before we can say that an
+ * instruction has executed.
+ *
+ * swint will set CANCELED, but it's a legitimate instruction. Fortunately
+ * it changes the PC. If it hasn't changed, then we know that the interrupt
+ * wasn't generated by swint and we'll need to run this process again before
+ * we can say an instruction has executed.
+ *
+ * If either CANCELED == 0 or the PC's changed, we send out SIGTRAPs and get
+ * on with our lives.
+ */
+
+void gx_singlestep_handle(struct pt_regs *regs, int fault_num)
+{
+ enum ctx_state prev_state = exception_enter();
+ unsigned long *ss_pc = this_cpu_ptr(&ss_saved_pc);
+ struct thread_info *info = (void *)current_thread_info();
+ int is_single_step = test_ti_thread_flag(info, TIF_SINGLESTEP);
+ unsigned long control = __insn_mfspr(SPR_SINGLE_STEP_CONTROL_K);
+
+ if (is_single_step == 0) {
+ __insn_mtspr(SPR_SINGLE_STEP_EN_K_K, 0);
+
+ } else if ((*ss_pc != regs->pc) ||
+ (!(control & SPR_SINGLE_STEP_CONTROL_1__CANCELED_MASK))) {
+
+ control |= SPR_SINGLE_STEP_CONTROL_1__CANCELED_MASK;
+ control |= SPR_SINGLE_STEP_CONTROL_1__INHIBIT_MASK;
+ __insn_mtspr(SPR_SINGLE_STEP_CONTROL_K, control);
+ send_sigtrap(current, regs);
+ }
+ exception_exit(prev_state);
+}
+
+
+/*
+ * Called from need_singlestep. Set up the control registers and the enable
+ * register, then return back.
+ */
+
+void single_step_once(struct pt_regs *regs)
+{
+ unsigned long *ss_pc = this_cpu_ptr(&ss_saved_pc);
+ unsigned long control = __insn_mfspr(SPR_SINGLE_STEP_CONTROL_K);
+
+ *ss_pc = regs->pc;
+ control |= SPR_SINGLE_STEP_CONTROL_1__CANCELED_MASK;
+ control |= SPR_SINGLE_STEP_CONTROL_1__INHIBIT_MASK;
+ __insn_mtspr(SPR_SINGLE_STEP_CONTROL_K, control);
+ __insn_mtspr(SPR_SINGLE_STEP_EN_K_K, 1 << USER_PL);
+}
+
+void single_step_execve(void)
+{
+ /* Nothing */
+}
+
+#endif /* !__tilegx__ */
Code Review / kvmfornfv.git / blobdiff