A checkpointed task image may specify a value for the DABR (Data
Access Breakpoint Register). The restart code needs to validate this
value before making any changes to the current task.
ptrace_set_debugreg encapsulates the bounds checking and platform
dependencies of programming the DABR. Split this into "validate"
(debugreg_valid) and "update" (debugreg_update) functions, and make
them available for use outside of the ptrace code.
Also ptrace_set_debugreg has extern linkage, but no users outside of
ptrace.c. Make it static.
Signed-off-by: Nathan Lynch <n...@pobox.com>
---
arch/powerpc/include/asm/ptrace.h | 6 +++
arch/powerpc/kernel/ptrace.c | 68 ++++++++++++++++++++----------------
2 files changed, 44 insertions(+), 30 deletions(-)
Is something like this okay to carry in the checkpoint/restart patches?
diff --git a/arch/powerpc/include/asm/ptrace.h
b/arch/powerpc/include/asm/ptrace.h
index c9c678f..1b3a5f0 100644
--- a/arch/powerpc/include/asm/ptrace.h
+++ b/arch/powerpc/include/asm/ptrace.h
@@ -81,6 +81,8 @@ struct pt_regs {
#ifndef __ASSEMBLY__
+#include <linux/types.h>
+
#define instruction_pointer(regs) ((regs)->nip)
#define user_stack_pointer(regs) ((regs)->gpr[1])
#define regs_return_value(regs) ((regs)->gpr[3])
@@ -138,6 +140,10 @@ do {
\
extern void user_enable_single_step(struct task_struct *);
extern void user_disable_single_step(struct task_struct *);
+/* for reprogramming DABR/DAC during restart of a checkpointed task */
+extern bool debugreg_valid(unsigned long val);
+extern void debugreg_update(struct task_struct *task, unsigned long val);
+
#endif /* __ASSEMBLY__ */
#endif /* __KERNEL__ */
diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c
index 3635be6..60259c6 100644
--- a/arch/powerpc/kernel/ptrace.c
+++ b/arch/powerpc/kernel/ptrace.c
@@ -735,22 +735,13 @@ void user_disable_single_step(struct task_struct *task)
clear_tsk_thread_flag(task, TIF_SINGLESTEP);
}
-int ptrace_set_debugreg(struct task_struct *task, unsigned long addr,
- unsigned long data)
+bool debugreg_valid(unsigned long val)
{
- /* For ppc64 we support one DABR and no IABR's at the moment (ppc64).
- * For embedded processors we support one DAC and no IAC's at the
- * moment.
- */
- if (addr > 0)
- return -EINVAL;
-
/* The bottom 3 bits in dabr are flags */
- if ((data & ~0x7UL) >= TASK_SIZE)
- return -EIO;
+ if ((val & ~0x7UL) >= TASK_SIZE)
+ return false;
#ifndef CONFIG_BOOKE
-
/* For processors using DABR (i.e. 970), the bottom 3 bits are flags.
* It was assumed, on previous implementations, that 3 bits were
* passed together with the data address, fitting the design of the
@@ -764,47 +755,64 @@ int ptrace_set_debugreg(struct task_struct *task,
unsigned long addr,
*/
/* Ensure breakpoint translation bit is set */
- if (data && !(data & DABR_TRANSLATION))
- return -EIO;
-
- /* Move contents to the DABR register */
- task->thread.dabr = data;
-
-#endif
-#if defined(CONFIG_BOOKE)
-
+ if (val && !(val & DABR_TRANSLATION))
+ return false;
+#else
/* As described above, it was assumed 3 bits were passed with the data
* address, but we will assume only the mode bits will be passed
* as to not cause alignment restrictions for DAC-based processors.
*/
+ /* Read or Write bits must be set */
+ if (!(val & 0x3UL))
+ return -EINVAL;
+#endif
+ return true;
+}
+
+void debugreg_update(struct task_struct *task, unsigned long val)
+{
+#ifndef CONFIG_BOOKE
+ task->thread.dabr = val;
+#else
/* DAC's hold the whole address without any mode flags */
- task->thread.dabr = data & ~0x3UL;
+ task->thread.dabr = val & ~0x3UL;
if (task->thread.dabr == 0) {
task->thread.dbcr0 &= ~(DBSR_DAC1R | DBSR_DAC1W | DBCR0_IDM);
task->thread.regs->msr &= ~MSR_DE;
- return 0;
}
- /* Read or Write bits must be set */
-
- if (!(data & 0x3UL))
- return -EINVAL;
-
/* Set the Internal Debugging flag (IDM bit 1) for the DBCR0
register */
task->thread.dbcr0 = DBCR0_IDM;
/* Check for write and read flags and set DBCR0
accordingly */
- if (data & 0x1UL)
+ if (val & 0x1UL)
task->thread.dbcr0 |= DBSR_DAC1R;
- if (data & 0x2UL)
+ if (val & 0x2UL)
task->thread.dbcr0 |= DBSR_DAC1W;
task->thread.regs->msr |= MSR_DE;
#endif
+}
+
+static int ptrace_set_debugreg(struct task_struct *task, unsigned long addr,
+ unsigned long data)
+{
+ /* For ppc64 we support one DABR and no IABR's at the moment (ppc64).
+ * For embedded processors we support one DAC and no IAC's at the
+ * moment.
+ */
+ if (addr > 0)
+ return -EINVAL;
+
+ if (!debugreg_valid(data))
+ return -EIO;
+
+ debugreg_update(task, data);
+
return 0;
}
--
1.6.0.6
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