diff options
| -rw-r--r-- | arch/x86/kernel/step.c | 64 | ||||
| -rw-r--r-- | arch/x86/kernel/traps_32.c | 6 | ||||
| -rw-r--r-- | arch/x86/kernel/traps_64.c | 6 | ||||
| -rw-r--r-- | include/asm-x86/ptrace.h | 7 |
4 files changed, 80 insertions, 3 deletions
diff --git a/arch/x86/kernel/step.c b/arch/x86/kernel/step.c index 243bff650ca..cf4b9dac4a0 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) return 0; } -void user_enable_single_step(struct task_struct *child) +/* + * Enable single-stepping. Return nonzero if user mode is not using TF itself. + */ +static int enable_single_step(struct task_struct *child) { struct pt_regs *regs = task_pt_regs(child); @@ -122,7 +125,7 @@ void user_enable_single_step(struct task_struct *child) * If TF was already set, don't do anything else */ if (regs->eflags & X86_EFLAGS_TF) - return; + return 0; /* Set TF on the kernel stack.. */ regs->eflags |= X86_EFLAGS_TF; @@ -133,13 +136,68 @@ void user_enable_single_step(struct task_struct *child) * won't clear it by hand later. */ if (is_setting_trap_flag(child, regs)) - return; + return 0; set_tsk_thread_flag(child, TIF_FORCED_TF); + + return 1; +} + +/* + * Install this value in MSR_IA32_DEBUGCTLMSR whenever child is running. + */ +static void write_debugctlmsr(struct task_struct *child, unsigned long val) +{ + child->thread.debugctlmsr = val; + + if (child != current) + return; + +#ifdef CONFIG_X86_64 + wrmsrl(MSR_IA32_DEBUGCTLMSR, val); +#else + wrmsr(MSR_IA32_DEBUGCTLMSR, val, 0); +#endif +} + +/* + * Enable single or block step. + */ +static void enable_step(struct task_struct *child, bool block) +{ + /* + * Make sure block stepping (BTF) is not enabled unless it should be. + * Note that we don't try to worry about any is_setting_trap_flag() + * instructions after the first when using block stepping. + * So noone should try to use debugger block stepping in a program + * that uses user-mode single stepping itself. + */ + if (enable_single_step(child) && block) { + set_tsk_thread_flag(child, TIF_DEBUGCTLMSR); + write_debugctlmsr(child, DEBUGCTLMSR_BTF); + } else if (test_and_clear_tsk_thread_flag(child, TIF_DEBUGCTLMSR)) { + write_debugctlmsr(child, 0); + } +} + +void user_enable_single_step(struct task_struct *child) +{ + enable_step(child, 0); +} + +void user_enable_block_step(struct task_struct *child) +{ + enable_step(child, 1); } void user_disable_single_step(struct task_struct *child) { + /* + * Make sure block stepping (BTF) is disabled. + */ + if (test_and_clear_tsk_thread_flag(child, TIF_DEBUGCTLMSR)) + write_debugctlmsr(child, 0); + /* Always clear TIF_SINGLESTEP... */ clear_tsk_thread_flag(child, TIF_SINGLESTEP); diff --git a/arch/x86/kernel/traps_32.c b/arch/x86/kernel/traps_32.c index 02d1e1e58e8..9b0bbd508cd 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) get_debugreg(condition, 6); + /* + * The processor cleared BTF, so don't mark that we need it set. + */ + clear_tsk_thread_flag(tsk, TIF_DEBUGCTLMSR); + tsk->thread.debugctlmsr = 0; + if (notify_die(DIE_DEBUG, "debug", regs, condition, error_code, SIGTRAP) == NOTIFY_STOP) return; diff --git a/arch/x86/kernel/traps_64.c b/arch/x86/kernel/traps_64.c index 874aca397b0..610a64d6bdf 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, get_debugreg(condition, 6); + /* + * The processor cleared BTF, so don't mark that we need it set. + */ + clear_tsk_thread_flag(tsk, TIF_DEBUGCTLMSR); + tsk->thread.debugctlmsr = 0; + if (notify_die(DIE_DEBUG, "debug", regs, condition, error_code, SIGTRAP) == NOTIFY_STOP) return; diff --git a/include/asm-x86/ptrace.h b/include/asm-x86/ptrace.h index d223decd7b0..04204f35929 100644 --- a/include/asm-x86/ptrace.h +++ b/include/asm-x86/ptrace.h @@ -150,6 +150,13 @@ enum { extern void user_enable_single_step(struct task_struct *); extern void user_disable_single_step(struct task_struct *); +extern void user_enable_block_step(struct task_struct *); +#ifdef CONFIG_X86_DEBUGCTLMSR +#define arch_has_block_step() (1) +#else +#define arch_has_block_step() (boot_cpu_data.x86 >= 6) +#endif + struct user_desc; extern int do_get_thread_area(struct task_struct *p, int idx, struct user_desc __user *info); |