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| author | Oleg Nesterov <oleg@redhat.com> | 2012-09-03 18:05:10 +0400 |
|---|---|---|
| committer | Oleg Nesterov <oleg@redhat.com> | 2012-09-15 19:37:31 +0400 |
| commit | 3a4664aa8362d9fa9110828f55afa9f9fcd7e484 (patch) | |
| tree | f2a4314a4e71b9273a15e7816197b38505c44092 | |
| parent | 9bd1190a11c9d2c59d35cb999b8d170ad52aab5f (diff) | |
| download | linux-3a4664aa8362d9fa9110828f55afa9f9fcd7e484.tar.xz | |
uprobes/x86: Xol should send SIGTRAP if X86_EFLAGS_TF was set
arch_uprobe_disable_step() correctly preserves X86_EFLAGS_TF and
returns to user-mode. But this means the application gets SIGTRAP
only after the next insn.
This means that UPROBE_CLEAR_TF logic is not really right. _enable
should only record the state of X86_EFLAGS_TF, and _disable should
check it separately from UPROBE_FIX_SETF.
Remove arch_uprobe_task->restore_flags, add ->saved_tf instead, and
change enable/disable accordingly. This assumes that the probed insn
was not trapped, see the next patch.
arch_uprobe_skip_sstep() logic has the same problem, change it to
check X86_EFLAGS_TF and send SIGTRAP as well. We will cleanup this
all after we fold enable/disable_step into pre/post_hol hooks.
Note: send_sig(SIGTRAP) is not actually right, we need send_sigtrap().
But this needs more changes, handle_swbp() does the same and this is
equally wrong.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
| -rw-r--r-- | arch/x86/include/asm/uprobes.h | 3 | ||||
| -rw-r--r-- | arch/x86/kernel/uprobes.c | 19 |
2 files changed, 14 insertions, 8 deletions
diff --git a/arch/x86/include/asm/uprobes.h b/arch/x86/include/asm/uprobes.h index cee58624cb30..d561ff5a3d4d 100644 --- a/arch/x86/include/asm/uprobes.h +++ b/arch/x86/include/asm/uprobes.h @@ -46,8 +46,7 @@ struct arch_uprobe_task { #ifdef CONFIG_X86_64 unsigned long saved_scratch_register; #endif -#define UPROBE_CLEAR_TF (1 << 0) - unsigned int restore_flags; + unsigned int saved_tf; }; extern int arch_uprobe_analyze_insn(struct arch_uprobe *aup, struct mm_struct *mm, unsigned long addr); diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c index 3b4aae68efe0..7e993d1f1992 100644 --- a/arch/x86/kernel/uprobes.c +++ b/arch/x86/kernel/uprobes.c @@ -653,7 +653,7 @@ void arch_uprobe_abort_xol(struct arch_uprobe *auprobe, struct pt_regs *regs) * Skip these instructions as per the currently known x86 ISA. * 0x66* { 0x90 | 0x0f 0x1f | 0x0f 0x19 | 0x87 0xc0 } */ -bool arch_uprobe_skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs) +static bool __skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs) { int i; @@ -681,16 +681,21 @@ bool arch_uprobe_skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs) return false; } +bool arch_uprobe_skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs) +{ + bool ret = __skip_sstep(auprobe, regs); + if (ret && (regs->flags & X86_EFLAGS_TF)) + send_sig(SIGTRAP, current, 0); + return ret; +} + void arch_uprobe_enable_step(struct arch_uprobe *auprobe) { struct task_struct *task = current; struct arch_uprobe_task *autask = &task->utask->autask; struct pt_regs *regs = task_pt_regs(task); - autask->restore_flags = 0; - if (!(regs->flags & X86_EFLAGS_TF) && - !(auprobe->fixups & UPROBE_FIX_SETF)) - autask->restore_flags |= UPROBE_CLEAR_TF; + autask->saved_tf = !!(regs->flags & X86_EFLAGS_TF); regs->flags |= X86_EFLAGS_TF; if (test_tsk_thread_flag(task, TIF_BLOCKSTEP)) @@ -707,6 +712,8 @@ void arch_uprobe_disable_step(struct arch_uprobe *auprobe) * SIGTRAP if we do not clear TF. We need to examine the opcode to * make it right. */ - if (autask->restore_flags & UPROBE_CLEAR_TF) + if (autask->saved_tf) + send_sig(SIGTRAP, task, 0); + else if (!(auprobe->fixups & UPROBE_FIX_SETF)) regs->flags &= ~X86_EFLAGS_TF; } |