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-rw-r--r--arch/x86/kernel/step.c64
-rw-r--r--arch/x86/kernel/traps_32.c6
-rw-r--r--arch/x86/kernel/traps_64.c6
-rw-r--r--include/asm-x86/ptrace.h7
4 files changed, 80 insertions, 3 deletions
diff --git a/arch/x86/kernel/step.c b/arch/x86/kernel/step.c
index 243bff650ca5..cf4b9dac4a05 100644
--- a/arch/x86/kernel/step.c
+++ b/arch/x86/kernel/step.c
@@ -107,7 +107,10 @@ static int is_setting_trap_flag(struct task_struct *child, struct pt_regs *regs)
107 return 0; 107 return 0;
108} 108}
109 109
110void user_enable_single_step(struct task_struct *child) 110/*
111 * Enable single-stepping. Return nonzero if user mode is not using TF itself.
112 */
113static int enable_single_step(struct task_struct *child)
111{ 114{
112 struct pt_regs *regs = task_pt_regs(child); 115 struct pt_regs *regs = task_pt_regs(child);
113 116
@@ -122,7 +125,7 @@ void user_enable_single_step(struct task_struct *child)
122 * If TF was already set, don't do anything else 125 * If TF was already set, don't do anything else
123 */ 126 */
124 if (regs->eflags & X86_EFLAGS_TF) 127 if (regs->eflags & X86_EFLAGS_TF)
125 return; 128 return 0;
126 129
127 /* Set TF on the kernel stack.. */ 130 /* Set TF on the kernel stack.. */
128 regs->eflags |= X86_EFLAGS_TF; 131 regs->eflags |= X86_EFLAGS_TF;
@@ -133,13 +136,68 @@ void user_enable_single_step(struct task_struct *child)
133 * won't clear it by hand later. 136 * won't clear it by hand later.
134 */ 137 */
135 if (is_setting_trap_flag(child, regs)) 138 if (is_setting_trap_flag(child, regs))
136 return; 139 return 0;
137 140
138 set_tsk_thread_flag(child, TIF_FORCED_TF); 141 set_tsk_thread_flag(child, TIF_FORCED_TF);
142
143 return 1;
144}
145
146/*
147 * Install this value in MSR_IA32_DEBUGCTLMSR whenever child is running.
148 */
149static void write_debugctlmsr(struct task_struct *child, unsigned long val)
150{
151 child->thread.debugctlmsr = val;
152
153 if (child != current)
154 return;
155
156#ifdef CONFIG_X86_64
157 wrmsrl(MSR_IA32_DEBUGCTLMSR, val);
158#else
159 wrmsr(MSR_IA32_DEBUGCTLMSR, val, 0);
160#endif
161}
162
163/*
164 * Enable single or block step.
165 */
166static void enable_step(struct task_struct *child, bool block)
167{
168 /*
169 * Make sure block stepping (BTF) is not enabled unless it should be.
170 * Note that we don't try to worry about any is_setting_trap_flag()
171 * instructions after the first when using block stepping.
172 * So noone should try to use debugger block stepping in a program
173 * that uses user-mode single stepping itself.
174 */
175 if (enable_single_step(child) && block) {
176 set_tsk_thread_flag(child, TIF_DEBUGCTLMSR);
177 write_debugctlmsr(child, DEBUGCTLMSR_BTF);
178 } else if (test_and_clear_tsk_thread_flag(child, TIF_DEBUGCTLMSR)) {
179 write_debugctlmsr(child, 0);
180 }
181}
182
183void user_enable_single_step(struct task_struct *child)
184{
185 enable_step(child, 0);
186}
187
188void user_enable_block_step(struct task_struct *child)
189{
190 enable_step(child, 1);
139} 191}
140 192
141void user_disable_single_step(struct task_struct *child) 193void user_disable_single_step(struct task_struct *child)
142{ 194{
195 /*
196 * Make sure block stepping (BTF) is disabled.
197 */
198 if (test_and_clear_tsk_thread_flag(child, TIF_DEBUGCTLMSR))
199 write_debugctlmsr(child, 0);
200
143 /* Always clear TIF_SINGLESTEP... */ 201 /* Always clear TIF_SINGLESTEP... */
144 clear_tsk_thread_flag(child, TIF_SINGLESTEP); 202 clear_tsk_thread_flag(child, TIF_SINGLESTEP);
145 203
diff --git a/arch/x86/kernel/traps_32.c b/arch/x86/kernel/traps_32.c
index 02d1e1e58e81..9b0bbd508cd5 100644
--- a/arch/x86/kernel/traps_32.c
+++ b/arch/x86/kernel/traps_32.c
@@ -837,6 +837,12 @@ fastcall void __kprobes do_debug(struct pt_regs * regs, long error_code)
837 837
838 get_debugreg(condition, 6); 838 get_debugreg(condition, 6);
839 839
840 /*
841 * The processor cleared BTF, so don't mark that we need it set.
842 */
843 clear_tsk_thread_flag(tsk, TIF_DEBUGCTLMSR);
844 tsk->thread.debugctlmsr = 0;
845
840 if (notify_die(DIE_DEBUG, "debug", regs, condition, error_code, 846 if (notify_die(DIE_DEBUG, "debug", regs, condition, error_code,
841 SIGTRAP) == NOTIFY_STOP) 847 SIGTRAP) == NOTIFY_STOP)
842 return; 848 return;
diff --git a/arch/x86/kernel/traps_64.c b/arch/x86/kernel/traps_64.c
index 874aca397b02..610a64d6bdf0 100644
--- a/arch/x86/kernel/traps_64.c
+++ b/arch/x86/kernel/traps_64.c
@@ -850,6 +850,12 @@ asmlinkage void __kprobes do_debug(struct pt_regs * regs,
850 850
851 get_debugreg(condition, 6); 851 get_debugreg(condition, 6);
852 852
853 /*
854 * The processor cleared BTF, so don't mark that we need it set.
855 */
856 clear_tsk_thread_flag(tsk, TIF_DEBUGCTLMSR);
857 tsk->thread.debugctlmsr = 0;
858
853 if (notify_die(DIE_DEBUG, "debug", regs, condition, error_code, 859 if (notify_die(DIE_DEBUG, "debug", regs, condition, error_code,
854 SIGTRAP) == NOTIFY_STOP) 860 SIGTRAP) == NOTIFY_STOP)
855 return; 861 return;
diff --git a/include/asm-x86/ptrace.h b/include/asm-x86/ptrace.h
index d223decd7b01..04204f359298 100644
--- a/include/asm-x86/ptrace.h
+++ b/include/asm-x86/ptrace.h
@@ -150,6 +150,13 @@ enum {
150extern void user_enable_single_step(struct task_struct *); 150extern void user_enable_single_step(struct task_struct *);
151extern void user_disable_single_step(struct task_struct *); 151extern void user_disable_single_step(struct task_struct *);
152 152
153extern void user_enable_block_step(struct task_struct *);
154#ifdef CONFIG_X86_DEBUGCTLMSR
155#define arch_has_block_step() (1)
156#else
157#define arch_has_block_step() (boot_cpu_data.x86 >= 6)
158#endif
159
153struct user_desc; 160struct user_desc;
154extern int do_get_thread_area(struct task_struct *p, int idx, 161extern int do_get_thread_area(struct task_struct *p, int idx,
155 struct user_desc __user *info); 162 struct user_desc __user *info);