Patchwork [v2,3/4] uprobes/powerpc: teach uprobes to ignore gdb breakpoints

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Submitter Ananth N Mavinakayanahalli
Date March 22, 2013, 3:18 p.m.
Message ID <20130322151838.GD20010@in.ibm.com>
Download mbox | patch
Permalink /patch/230092/
State Awaiting Upstream, archived
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Comments

Ananth N Mavinakayanahalli - March 22, 2013, 3:18 p.m.
From: Ananth N Mavinakayanahalli <ananth@in.ibm.com>

Powerpc has many trap variants that could be used by entities like gdb.
Currently, running gdb on a program being traced by uprobes causes an
endless loop since uprobes doesn't understand that the trap was inserted
by some other entity and a SIGTRAP needs to be delivered.

Teach uprobes to ignore breakpoints that do not belong to it.

Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
---
 arch/powerpc/kernel/uprobes.c |   10 ++++++++++
 1 file changed, 10 insertions(+)
Srikar Dronamraju - March 26, 2013, 12:06 p.m.
* Ananth N Mavinakayanahalli <ananth@in.ibm.com> [2013-03-22 20:48:38]:

> From: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
> 
> Powerpc has many trap variants that could be used by entities like gdb.
> Currently, running gdb on a program being traced by uprobes causes an
> endless loop since uprobes doesn't understand that the trap was inserted
> by some other entity and a SIGTRAP needs to be delivered.
> 
> Teach uprobes to ignore breakpoints that do not belong to it.
> 
> Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>

Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>

> ---
>  arch/powerpc/kernel/uprobes.c |   10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> Index: linux-3.9-rc3/arch/powerpc/kernel/uprobes.c
> ===================================================================
> --- linux-3.9-rc3.orig/arch/powerpc/kernel/uprobes.c
> +++ linux-3.9-rc3/arch/powerpc/kernel/uprobes.c
> @@ -31,6 +31,16 @@
>  #define UPROBE_TRAP_NR	UINT_MAX
> 
>  /**
> + * is_trap_insn - check if the instruction is a trap variant
> + * @insn: instruction to be checked.
> + * Returns true if @insn is a trap variant.
> + */
> +bool is_trap_insn(uprobe_opcode_t *insn)
> +{
> +	return (is_trap(*insn));
> +}
> +
> +/**
>   * arch_uprobe_analyze_insn
>   * @mm: the probed address space.
>   * @arch_uprobe: the probepoint information.

Patch

Index: linux-3.9-rc3/arch/powerpc/kernel/uprobes.c
===================================================================
--- linux-3.9-rc3.orig/arch/powerpc/kernel/uprobes.c
+++ linux-3.9-rc3/arch/powerpc/kernel/uprobes.c
@@ -31,6 +31,16 @@ 
 #define UPROBE_TRAP_NR	UINT_MAX
 
 /**
+ * is_trap_insn - check if the instruction is a trap variant
+ * @insn: instruction to be checked.
+ * Returns true if @insn is a trap variant.
+ */
+bool is_trap_insn(uprobe_opcode_t *insn)
+{
+	return (is_trap(*insn));
+}
+
+/**
  * arch_uprobe_analyze_insn
  * @mm: the probed address space.
  * @arch_uprobe: the probepoint information.