2 * User-space Probes (UProbes) for sparc
4 * Copyright (C) 2013 Oracle Inc.
6 * This program is free software: you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation, either version 2 of the License, or
9 * (at your option) any later version.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
16 * You should have received a copy of the GNU General Public License
17 * along with this program. If not, see <http://www.gnu.org/licenses/>.
20 * Jose E. Marchesi <jose.marchesi@oracle.com>
21 * Eric Saint Etienne <eric.saint.etienne@oracle.com>
24 #include <linux/kernel.h>
25 #include <linux/highmem.h>
26 #include <linux/uprobes.h>
27 #include <linux/uaccess.h>
28 #include <linux/sched.h> /* For struct task_struct */
29 #include <linux/kdebug.h>
31 #include <asm/cacheflush.h>
33 /* Compute the address of the breakpoint instruction and return it.
35 * Note that uprobe_get_swbp_addr is defined as a weak symbol in
36 * kernel/events/uprobe.c.
38 unsigned long uprobe_get_swbp_addr(struct pt_regs *regs)
40 return instruction_pointer(regs);
43 static void copy_to_page(struct page *page, unsigned long vaddr,
44 const void *src, int len)
46 void *kaddr = kmap_atomic(page);
48 memcpy(kaddr + (vaddr & ~PAGE_MASK), src, len);
52 /* Fill in the xol area with the probed instruction followed by the
53 * single-step trap. Some fixups in the copied instruction are
54 * performed at this point.
56 * Note that uprobe_xol_copy is defined as a weak symbol in
57 * kernel/events/uprobe.c.
59 void arch_uprobe_copy_ixol(struct page *page, unsigned long vaddr,
60 void *src, unsigned long len)
62 const u32 stp_insn = UPROBE_STP_INSN;
63 u32 insn = *(u32 *) src;
65 /* Branches annulling their delay slot must be fixed to not do
66 * so. Clearing the annul bit on these instructions we can be
67 * sure the single-step breakpoint in the XOL slot will be
71 u32 op = (insn >> 30) & 0x3;
72 u32 op2 = (insn >> 22) & 0x7;
75 (op2 == 1 || op2 == 2 || op2 == 3 || op2 == 5 || op2 == 6) &&
76 (insn & ANNUL_BIT) == ANNUL_BIT)
79 copy_to_page(page, vaddr, &insn, len);
80 copy_to_page(page, vaddr+len, &stp_insn, 4);
84 /* Instruction analysis/validity.
86 * This function returns 0 on success or a -ve number on error.
88 int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe,
89 struct mm_struct *mm, unsigned long addr)
91 /* Any unsupported instruction? Then return -EINVAL */
95 /* If INSN is a relative control transfer instruction, return the
96 * corrected branch destination value.
98 * Note that regs->tpc and regs->tnpc still hold the values of the
99 * program counters at the time of the single-step trap due to the
100 * execution of the UPROBE_STP_INSN at utask->xol_vaddr + 4.
103 static unsigned long relbranch_fixup(u32 insn, struct uprobe_task *utask,
104 struct pt_regs *regs)
106 /* Branch not taken, no mods necessary. */
107 if (regs->tnpc == regs->tpc + 0x4UL)
108 return utask->autask.saved_tnpc + 0x4UL;
110 /* The three cases are call, branch w/prediction,
111 * and traditional branch.
113 if ((insn & 0xc0000000) == 0x40000000 ||
114 (insn & 0xc1c00000) == 0x00400000 ||
115 (insn & 0xc1c00000) == 0x00800000) {
116 unsigned long real_pc = (unsigned long) utask->vaddr;
117 unsigned long ixol_addr = utask->xol_vaddr;
119 /* The instruction did all the work for us
120 * already, just apply the offset to the correct
121 * instruction location.
123 return (real_pc + (regs->tnpc - ixol_addr));
126 /* It is jmpl or some other absolute PC modification instruction,
132 /* If INSN is an instruction which writes its PC location
133 * into a destination register, fix that up.
135 static int retpc_fixup(struct pt_regs *regs, u32 insn,
136 unsigned long real_pc)
138 unsigned long *slot = NULL;
141 /* Simplest case is 'call', which always uses %o7 */
142 if ((insn & 0xc0000000) == 0x40000000)
143 slot = ®s->u_regs[UREG_I7];
145 /* 'jmpl' encodes the register inside of the opcode */
146 if ((insn & 0xc1f80000) == 0x81c00000) {
147 unsigned long rd = ((insn >> 25) & 0x1f);
150 slot = ®s->u_regs[rd];
152 unsigned long fp = regs->u_regs[UREG_FP];
153 /* Hard case, it goes onto the stack. */
157 if (test_thread_64bit_stack(fp)) {
158 unsigned long __user *uslot =
159 (unsigned long __user *) (fp + STACK_BIAS) + rd;
160 rc = __put_user(real_pc, uslot);
162 unsigned int __user *uslot = (unsigned int
164 rc = __put_user((u32) real_pc, uslot);
173 /* Single-stepping can be avoided for certain instructions: NOPs and
174 * instructions that can be emulated. This function determines
175 * whether the instruction where the uprobe is installed falls in one
176 * of these cases and emulates it.
178 * This function returns true if the single-stepping can be skipped,
181 bool arch_uprobe_skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs)
183 /* We currently only emulate NOP instructions.
186 if (auprobe->ixol == (1 << 24)) {
195 /* Prepare to execute out of line. At this point
196 * current->utask->xol_vaddr points to an allocated XOL slot properly
197 * initialized with the original instruction and the single-stepping
200 * This function returns 0 on success, any other number on error.
202 int arch_uprobe_pre_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
204 struct uprobe_task *utask = current->utask;
205 struct arch_uprobe_task *autask = ¤t->utask->autask;
207 /* Save the current program counters so they can be restored
210 autask->saved_tpc = regs->tpc;
211 autask->saved_tnpc = regs->tnpc;
213 /* Adjust PC and NPC so the first instruction in the XOL slot
214 * will be executed by the user task.
216 instruction_pointer_set(regs, utask->xol_vaddr);
221 /* Prepare to resume execution after the single-step. Called after
222 * single-stepping. To avoid the SMP problems that can occur when we
223 * temporarily put back the original opcode to single-step, we
224 * single-stepped a copy of the instruction.
226 * This function returns 0 on success, any other number on error.
228 int arch_uprobe_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
230 struct uprobe_task *utask = current->utask;
231 struct arch_uprobe_task *autask = &utask->autask;
232 u32 insn = auprobe->ixol;
235 if (utask->state == UTASK_SSTEP_ACK) {
236 regs->tnpc = relbranch_fixup(insn, utask, regs);
237 regs->tpc = autask->saved_tnpc;
238 rc = retpc_fixup(regs, insn, (unsigned long) utask->vaddr);
240 regs->tnpc = utask->vaddr+4;
241 regs->tpc = autask->saved_tnpc+4;
246 /* Handler for uprobe traps. This is called from the traps table and
247 * triggers the proper die notification.
249 asmlinkage void uprobe_trap(struct pt_regs *regs,
250 unsigned long trap_level)
252 BUG_ON(trap_level != 0x173 && trap_level != 0x174);
254 /* We are only interested in user-mode code. Uprobe traps
255 * shall not be present in kernel code.
257 if (!user_mode(regs)) {
259 bad_trap(regs, trap_level);
263 /* trap_level == 0x173 --> ta 0x73
264 * trap_level == 0x174 --> ta 0x74
266 if (notify_die((trap_level == 0x173) ? DIE_BPT : DIE_SSTEP,
267 (trap_level == 0x173) ? "bpt" : "sstep",
268 regs, 0, trap_level, SIGTRAP) != NOTIFY_STOP)
269 bad_trap(regs, trap_level);
272 /* Callback routine for handling die notifications.
274 int arch_uprobe_exception_notify(struct notifier_block *self,
275 unsigned long val, void *data)
277 int ret = NOTIFY_DONE;
278 struct die_args *args = (struct die_args *)data;
280 /* We are only interested in userspace traps */
281 if (args->regs && !user_mode(args->regs))
286 if (uprobe_pre_sstep_notifier(args->regs))
291 if (uprobe_post_sstep_notifier(args->regs))
301 /* This function gets called when a XOL instruction either gets
302 * trapped or the thread has a fatal signal, so reset the instruction
303 * pointer to its probed address.
305 void arch_uprobe_abort_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
307 struct uprobe_task *utask = current->utask;
309 instruction_pointer_set(regs, utask->vaddr);
312 /* If xol insn itself traps and generates a signal(Say,
313 * SIGILL/SIGSEGV/etc), then detect the case where a singlestepped
314 * instruction jumps back to its own address.
316 bool arch_uprobe_xol_was_trapped(struct task_struct *t)
322 arch_uretprobe_hijack_return_addr(unsigned long trampoline_vaddr,
323 struct pt_regs *regs)
325 unsigned long orig_ret_vaddr = regs->u_regs[UREG_I7];
327 regs->u_regs[UREG_I7] = trampoline_vaddr-8;
329 return orig_ret_vaddr + 8;