@@ -276,6 +276,7 @@ static inline unsigned long regs_get_kernel_stack_nth(struct pt_regs *regs,
#define PT_DAR 41
#define PT_DSISR 42
#define PT_RESULT 43
+#define PT_DSCR 44
#define PT_REGS_COUNT 44
#define PT_FPR0 48 /* each FP reg occupies 2 slots in this space */
@@ -179,6 +179,18 @@ static int set_user_msr(struct task_struct *task, unsigned long msr)
return 0;
}
+static unsigned long get_user_dscr(struct task_struct *task)
+{
+ return task->thread.dscr;
+}
+
+static int set_user_dscr(struct task_struct *task, unsigned long dscr)
+{
+ task->thread.dscr = dscr;
+ task->thread.dscr_inherit = 1;
+ return 0;
+}
+
/*
* We prevent mucking around with the reserved area of trap
* which are used internally by the kernel.
@@ -200,6 +212,9 @@ unsigned long ptrace_get_reg(struct task_struct *task, int regno)
if (regno == PT_MSR)
return get_user_msr(task);
+ if (regno == PT_DSCR)
+ return get_user_dscr(task);
+
if (regno < (sizeof(struct pt_regs) / sizeof(unsigned long)))
return ((unsigned long *)task->thread.regs)[regno];
@@ -218,6 +233,8 @@ int ptrace_put_reg(struct task_struct *task, int regno, unsigned long data)
return set_user_msr(task, data);
if (regno == PT_TRAP)
return set_user_trap(task, data);
+ if (regno == PT_DSCR)
+ return set_user_dscr(task, data);
if (regno <= PT_MAX_PUT_REG) {
((unsigned long *)task->thread.regs)[regno] = data;
The DSCR (aka Data Stream Control Register) is supported on some server PowerPC chips and allow some control over the prefetch of data streams. The kernel already supports DSCR value per thread but there is also a need in a ability to change it from an external process for the specific pid. The patch adds new register index PT_DSCR (index=44) which can be set/get by: ptrace(PTRACE_POKEUSER, traced_process, PT_DSCR << 3, dscr); dscr = ptrace(PTRACE_PEEKUSER, traced_process, PT_DSCR << 3, NULL); Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru> --- arch/powerpc/include/asm/ptrace.h | 1 + arch/powerpc/kernel/ptrace.c | 17 +++++++++++++++++ 2 files changed, 18 insertions(+)