From 5b0e508415a83989fe704b4718a1a214bc333ca7 Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Mon, 10 Mar 2008 13:11:17 +0000 Subject: x86: prevent unconditional writes to DebugCtl MSR Otherwise, enabling (or better, subsequent disabling) of single stepping would cause a kernel oops on CPUs not having this MSR. The patch could have been added a conditional to the MSR write in user_disable_single_step(), but centralizing the updates seems safer and (looking forward) better manageable. Signed-off-by: Jan Beulich Cc: Markus Metzger Signed-off-by: Ingo Molnar --- arch/x86/kernel/kprobes.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'arch/x86/kernel/kprobes.c') diff --git a/arch/x86/kernel/kprobes.c b/arch/x86/kernel/kprobes.c index 34a591283f5d..1e3de7db9ad5 100644 --- a/arch/x86/kernel/kprobes.c +++ b/arch/x86/kernel/kprobes.c @@ -410,13 +410,13 @@ static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs, static void __kprobes clear_btf(void) { if (test_thread_flag(TIF_DEBUGCTLMSR)) - wrmsrl(MSR_IA32_DEBUGCTLMSR, 0); + update_debugctlmsr(0); } static void __kprobes restore_btf(void) { if (test_thread_flag(TIF_DEBUGCTLMSR)) - wrmsrl(MSR_IA32_DEBUGCTLMSR, current->thread.debugctlmsr); + update_debugctlmsr(current->thread.debugctlmsr); } static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs) -- cgit v1.2.3-59-g8ed1b From acb5b8a2dd0f901463d075382ea548935e679f4e Mon Sep 17 00:00:00 2001 From: Yakov Lerner Date: Sun, 16 Mar 2008 03:21:21 -0500 Subject: x86, kprobes: correct post-eip value in post_hander() I was trying to get the address of instruction to be executed next after the kprobed instruction. But regs->eip in post_handler() contains value which is useless to the user. It's pre-corrected value. This value is difficult to use without access to resume_execution(), which is not exported anyway. I moved the invocation of post_handler() to *after* resume_execution(). Now regs->eip contains meaningful value in post_handler(). I do not think this change breaks any backward-compatibility. To make meaning of the old value, post_handler() would need access to resume_execution() which is not exported. I have difficulty to believe that previous, uncorrected, regs->eip can be meaningfully used in post_handler(). Signed-off-by: Yakov Lerner Acked-by: Ananth N Mavinakayanahalli Acked-by: Masami Hiramatsu Signed-off-by: Ingo Molnar --- arch/x86/kernel/kprobes.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'arch/x86/kernel/kprobes.c') diff --git a/arch/x86/kernel/kprobes.c b/arch/x86/kernel/kprobes.c index 1e3de7db9ad5..cc8ae90103ff 100644 --- a/arch/x86/kernel/kprobes.c +++ b/arch/x86/kernel/kprobes.c @@ -858,15 +858,15 @@ static int __kprobes post_kprobe_handler(struct pt_regs *regs) if (!cur) return 0; + resume_execution(cur, regs, kcb); + regs->flags |= kcb->kprobe_saved_flags; + trace_hardirqs_fixup_flags(regs->flags); + if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) { kcb->kprobe_status = KPROBE_HIT_SSDONE; cur->post_handler(cur, regs, 0); } - resume_execution(cur, regs, kcb); - regs->flags |= kcb->kprobe_saved_flags; - trace_hardirqs_fixup_flags(regs->flags); - /* Restore back the original saved kprobes variables and continue. */ if (kcb->kprobe_status == KPROBE_REENTER) { restore_previous_kprobe(kcb); -- cgit v1.2.3-59-g8ed1b From a5c15d419d4b68535222b51f9054dd08d5e67470 Mon Sep 17 00:00:00 2001 From: "gorcunov@gmail.com" Date: Fri, 28 Mar 2008 17:56:56 +0300 Subject: x86: replace most VM86 flags with flags from processor-flags.h Signed-off-by: Cyrill Gorcunov Signed-off-by: Ingo Molnar --- arch/x86/kernel/kprobes.c | 2 +- arch/x86/kernel/signal_32.c | 4 ++-- arch/x86/kernel/vm86_32.c | 34 +++++++++++++++++----------------- include/asm-x86/vm86.h | 10 ++-------- 4 files changed, 22 insertions(+), 28 deletions(-) (limited to 'arch/x86/kernel/kprobes.c') diff --git a/arch/x86/kernel/kprobes.c b/arch/x86/kernel/kprobes.c index cc8ae90103ff..b8c6743a13da 100644 --- a/arch/x86/kernel/kprobes.c +++ b/arch/x86/kernel/kprobes.c @@ -489,7 +489,7 @@ static int __kprobes reenter_kprobe(struct kprobe *p, struct pt_regs *regs, break; case KPROBE_HIT_SS: if (p == kprobe_running()) { - regs->flags &= ~TF_MASK; + regs->flags &= ~X86_EFLAGS_TF; regs->flags |= kcb->kprobe_saved_flags; return 0; } else { diff --git a/arch/x86/kernel/signal_32.c b/arch/x86/kernel/signal_32.c index aa1b6a0a22e4..f1b117930837 100644 --- a/arch/x86/kernel/signal_32.c +++ b/arch/x86/kernel/signal_32.c @@ -419,7 +419,7 @@ setup_frame(int sig, struct k_sigaction *ka, sigset_t *set, * The tracer may want to single-step inside the * handler too. */ - regs->flags &= ~(TF_MASK | X86_EFLAGS_DF); + regs->flags &= ~(X86_EFLAGS_TF | X86_EFLAGS_DF); if (test_thread_flag(TIF_SINGLESTEP)) ptrace_notify(SIGTRAP); @@ -507,7 +507,7 @@ static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, * The tracer may want to single-step inside the * handler too. */ - regs->flags &= ~(TF_MASK | X86_EFLAGS_DF); + regs->flags &= ~(X86_EFLAGS_TF | X86_EFLAGS_DF); if (test_thread_flag(TIF_SINGLESTEP)) ptrace_notify(SIGTRAP); diff --git a/arch/x86/kernel/vm86_32.c b/arch/x86/kernel/vm86_32.c index c866c00f4a85..38f566fa27d2 100644 --- a/arch/x86/kernel/vm86_32.c +++ b/arch/x86/kernel/vm86_32.c @@ -139,7 +139,7 @@ struct pt_regs *save_v86_state(struct kernel_vm86_regs *regs) printk("no vm86_info: BAD\n"); do_exit(SIGSEGV); } - set_flags(regs->pt.flags, VEFLAGS, VIF_MASK | current->thread.v86mask); + set_flags(regs->pt.flags, VEFLAGS, X86_EFLAGS_VIF | current->thread.v86mask); tmp = copy_vm86_regs_to_user(¤t->thread.vm86_info->regs, regs); tmp += put_user(current->thread.screen_bitmap, ¤t->thread.vm86_info->screen_bitmap); if (tmp) { @@ -306,13 +306,13 @@ static void do_sys_vm86(struct kernel_vm86_struct *info, struct task_struct *tsk tsk->thread.v86mask = 0; break; case CPU_386: - tsk->thread.v86mask = NT_MASK | IOPL_MASK; + tsk->thread.v86mask = X86_EFLAGS_NT | X86_EFLAGS_IOPL; break; case CPU_486: - tsk->thread.v86mask = AC_MASK | NT_MASK | IOPL_MASK; + tsk->thread.v86mask = X86_EFLAGS_AC | X86_EFLAGS_NT | X86_EFLAGS_IOPL; break; default: - tsk->thread.v86mask = ID_MASK | AC_MASK | NT_MASK | IOPL_MASK; + tsk->thread.v86mask = X86_EFLAGS_ID | X86_EFLAGS_AC | X86_EFLAGS_NT | X86_EFLAGS_IOPL; break; } @@ -363,24 +363,24 @@ static inline void return_to_32bit(struct kernel_vm86_regs *regs16, int retval) static inline void set_IF(struct kernel_vm86_regs *regs) { - VEFLAGS |= VIF_MASK; - if (VEFLAGS & VIP_MASK) + VEFLAGS |= X86_EFLAGS_VIF; + if (VEFLAGS & X86_EFLAGS_VIP) return_to_32bit(regs, VM86_STI); } static inline void clear_IF(struct kernel_vm86_regs *regs) { - VEFLAGS &= ~VIF_MASK; + VEFLAGS &= ~X86_EFLAGS_VIF; } static inline void clear_TF(struct kernel_vm86_regs *regs) { - regs->pt.flags &= ~TF_MASK; + regs->pt.flags &= ~X86_EFLAGS_TF; } static inline void clear_AC(struct kernel_vm86_regs *regs) { - regs->pt.flags &= ~AC_MASK; + regs->pt.flags &= ~X86_EFLAGS_AC; } /* @@ -399,7 +399,7 @@ static inline void set_vflags_long(unsigned long flags, struct kernel_vm86_regs { set_flags(VEFLAGS, flags, current->thread.v86mask); set_flags(regs->pt.flags, flags, SAFE_MASK); - if (flags & IF_MASK) + if (flags & X86_EFLAGS_IF) set_IF(regs); else clear_IF(regs); @@ -409,7 +409,7 @@ static inline void set_vflags_short(unsigned short flags, struct kernel_vm86_reg { set_flags(VFLAGS, flags, current->thread.v86mask); set_flags(regs->pt.flags, flags, SAFE_MASK); - if (flags & IF_MASK) + if (flags & X86_EFLAGS_IF) set_IF(regs); else clear_IF(regs); @@ -419,9 +419,9 @@ static inline unsigned long get_vflags(struct kernel_vm86_regs *regs) { unsigned long flags = regs->pt.flags & RETURN_MASK; - if (VEFLAGS & VIF_MASK) - flags |= IF_MASK; - flags |= IOPL_MASK; + if (VEFLAGS & X86_EFLAGS_VIF) + flags |= X86_EFLAGS_IF; + flags |= X86_EFLAGS_IOPL; return flags | (VEFLAGS & current->thread.v86mask); } @@ -573,11 +573,11 @@ void handle_vm86_fault(struct kernel_vm86_regs *regs, long error_code) #define CHECK_IF_IN_TRAP \ if (VMPI.vm86dbg_active && VMPI.vm86dbg_TFpendig) \ - newflags |= TF_MASK + newflags |= X86_EFLAGS_TF #define VM86_FAULT_RETURN do { \ - if (VMPI.force_return_for_pic && (VEFLAGS & (IF_MASK | VIF_MASK))) \ + if (VMPI.force_return_for_pic && (VEFLAGS & (X86_EFLAGS_IF | X86_EFLAGS_VIF))) \ return_to_32bit(regs, VM86_PICRETURN); \ - if (orig_flags & TF_MASK) \ + if (orig_flags & X86_EFLAGS_TF) \ handle_vm86_trap(regs, 0, 1); \ return; } while (0) diff --git a/include/asm-x86/vm86.h b/include/asm-x86/vm86.h index f5f3dc479c34..074b357146df 100644 --- a/include/asm-x86/vm86.h +++ b/include/asm-x86/vm86.h @@ -12,19 +12,13 @@ * Linus */ -#define TF_MASK 0x00000100 -#define IF_MASK 0x00000200 -#define IOPL_MASK 0x00003000 -#define NT_MASK 0x00004000 +#include + #ifdef CONFIG_VM86 #define X86_VM_MASK X86_EFLAGS_VM #else #define X86_VM_MASK 0 /* No VM86 support */ #endif -#define AC_MASK 0x00040000 -#define VIF_MASK 0x00080000 /* virtual interrupt flag */ -#define VIP_MASK 0x00100000 /* virtual interrupt pending */ -#define ID_MASK 0x00200000 #define BIOSSEG 0x0f000 -- cgit v1.2.3-59-g8ed1b