Messages in this thread Patch in this message | | | Date | Tue, 22 Apr 2014 16:47:49 +0200 | From | Oleg Nesterov <> | Subject | [PATCH 4/5] uprobes/x86: Move UPROBE_FIX_SETF logic from arch_uprobe_post_xol() to default_post_xol_op() |
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UPROBE_FIX_SETF is only needed to handle "popf" correctly but it is processed by the generic arch_uprobe_post_xol() code. This doesn't allows us to make ->fixups private for default_xol_ops.
1 Change default_post_xol_op(UPROBE_FIX_SETF) to set ->saved_tf = T.
"popf" always reads the flags from stack, it doesn't matter if TF was set or not before single-step. Ignoring the naming, this is even more logical, "saved_tf" means "owned by application" and we do not own this flag after "popf".
2. Change arch_uprobe_post_xol() to save ->saved_tf into the local "bool send_sigtrap" before ->post_xol().
2. Change arch_uprobe_post_xol() to ignore UPROBE_FIX_SETF and just check ->saved_tf after ->post_xol().
With this patch ->fixups and ->rip_rela_target_address are only used by default_xol_ops hooks, we are ready to remove them from the common part of arch_uprobe.
Signed-off-by: Oleg Nesterov <oleg@redhat.com> --- arch/x86/kernel/uprobes.c | 20 ++++++++++++-------- 1 files changed, 12 insertions(+), 8 deletions(-)
diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c index 4e2cdd5..e6314a2 100644 --- a/arch/x86/kernel/uprobes.c +++ b/arch/x86/kernel/uprobes.c @@ -441,6 +441,9 @@ static int default_post_xol_op(struct arch_uprobe *auprobe, struct pt_regs *regs return -ERESTART; } } + /* popf; tell the caller to not touch TF */ + if (auprobe->fixups & UPROBE_FIX_SETF) + utask->autask.saved_tf = true; return 0; } @@ -746,15 +749,15 @@ bool arch_uprobe_xol_was_trapped(struct task_struct *t) int arch_uprobe_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs) { struct uprobe_task *utask = current->utask; + bool send_sigtrap = utask->autask.saved_tf; + int err = 0; WARN_ON_ONCE(current->thread.trap_nr != UPROBE_TRAP_NR); current->thread.trap_nr = utask->autask.saved_trap_nr; if (auprobe->ops->post_xol) { - int err = auprobe->ops->post_xol(auprobe, regs); + err = auprobe->ops->post_xol(auprobe, regs); if (err) { - if (!utask->autask.saved_tf) - regs->flags &= ~X86_EFLAGS_TF; /* * Restore ->ip for restart or post mortem analysis. * ->post_xol() must not return -ERESTART unless this @@ -762,8 +765,8 @@ int arch_uprobe_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs) */ regs->ip = utask->vaddr; if (err == -ERESTART) - return 0; - return err; + err = 0; + send_sigtrap = false; } } /* @@ -771,12 +774,13 @@ int arch_uprobe_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs) * so we can get an extra SIGTRAP if we do not clear TF. We need * to examine the opcode to make it right. */ - if (utask->autask.saved_tf) + if (send_sigtrap) send_sig(SIGTRAP, current, 0); - else if (!(auprobe->fixups & UPROBE_FIX_SETF)) + + if (!utask->autask.saved_tf) regs->flags &= ~X86_EFLAGS_TF; - return 0; + return err; } /* callback routine for handling exceptions. */ -- 1.5.5.1
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