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From: Frederic Weisbecker on 23 Apr 2010 01:20
Tag ptrace breakpoints with the exclude_kernel attribute set. This
will make it easier to set generic policies on breakpoints, when it
comes to ensure nobody unpriviliged try to breakpoint on the kernel.

Signed-off-by: Frederic Weisbecker <fweisbec(a)gmail.com>
Cc: Will Deacon <will.deacon(a)arm.com>
Cc: Mahesh Salgaonkar <mahesh(a)linux.vnet.ibm.com>
Cc: K. Prasad <prasad(a)linux.vnet.ibm.com>
Cc: Paul Mundt <lethal(a)linux-sh.org>
Cc: Benjamin Herrenschmidt <benh(a)kernel.crashing.org>
Cc: Paul Mackerras <paulus(a)samba.org>
Cc: Ingo Molnar <mingo(a)elte.hu>
---
arch/sh/kernel/ptrace_32.c | 2 +-
arch/x86/kernel/ptrace.c | 2 +-
include/linux/hw_breakpoint.h | 6 ++++++
3 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/arch/sh/kernel/ptrace_32.c b/arch/sh/kernel/ptrace_32.c
index 7759a9a..d4104ce 100644
--- a/arch/sh/kernel/ptrace_32.c
+++ b/arch/sh/kernel/ptrace_32.c
@@ -85,7 +85,7 @@ static int set_single_step(struct task_struct *tsk, unsigned long addr)

bp = thread->ptrace_bps[0];
if (!bp) {
- hw_breakpoint_init(&attr);
+ ptrace_breakpoint_init(&attr);

attr.bp_addr = addr;
attr.bp_len = HW_BREAKPOINT_LEN_2;
diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
index 055be0a..70c4872 100644
--- a/arch/x86/kernel/ptrace.c
+++ b/arch/x86/kernel/ptrace.c
@@ -688,7 +688,7 @@ static int ptrace_set_breakpoint_addr(struct task_struct *tsk, int nr,
struct perf_event_attr attr;

if (!t->ptrace_bps[nr]) {
- hw_breakpoint_init(&attr);
+ ptrace_breakpoint_init(&attr);
/*
* Put stub len and type to register (reserve) an inactive but
* correct bp
diff --git a/include/linux/hw_breakpoint.h b/include/linux/hw_breakpoint.h
index c70d27a..a0aa5a9 100644
--- a/include/linux/hw_breakpoint.h
+++ b/include/linux/hw_breakpoint.h
@@ -34,6 +34,12 @@ static inline void hw_breakpoint_init(struct perf_event_attr *attr)
attr->sample_period = 1;
}

+static inline void ptrace_breakpoint_init(struct perf_event_attr *attr)
+{
+ hw_breakpoint_init(attr);
+ attr->exclude_kernel = 1;
+}
+
static inline unsigned long hw_breakpoint_addr(struct perf_event *bp)
{
return bp->attr.bp_addr;
--
1.6.2.3

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Prev: [PATCH 2/6] hw-breakpoints: Check disabled breakpoints again
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