x86, bts, ptrace: move BTS buffer allocation from ds.c into ptrace.c

Impact: restructure DS memory allocation to be done by the usage site of DS

Require pre-allocated buffers in ds.h.

Move the BTS buffer allocation for ptrace into ptrace.c.
The pointer to the allocated buffer is stored in the traced task's
task_struct together with the handle returned by ds_request_bts().

Removes memory accounting code.

Signed-off-by: Markus Metzger <markus.t.metzger@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 20 insertions, 2 deletions

diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
index 76adf5b640ff..2c8ec1ba75e6 100644
--- a/arch/x86/kernel/ptrace.c
+++ b/arch/x86/kernel/ptrace.c
@@ -758,6 +758,10 @@ static int ptrace_bts_config(struct task_struct *child,
                 bts_ovfl_callback_t ovfl = NULL;
                 unsigned int sig = 0;
 
+                error = -EINVAL;
+                if (cfg.size < (10 * bts_cfg.sizeof_bts))
+                        goto errout;
+
                 if (cfg.flags & PTRACE_BTS_O_SIGNAL) {
                         if (!cfg.signal)
                                 goto errout;
@@ -768,14 +772,26 @@ static int ptrace_bts_config(struct task_struct *child,
                         sig  = cfg.signal;
                 }
 
-                if (child->bts)
+                if (child->bts) {
                         (void)ds_release_bts(child->bts);
+                        kfree(child->bts_buffer);
+
+                        child->bts = NULL;
+                        child->bts_buffer = NULL;
+                }
+
+                error = -ENOMEM;
+                child->bts_buffer = kzalloc(cfg.size, GFP_KERNEL);
+                if (!child->bts_buffer)
+                        goto errout;
 
-                child->bts = ds_request_bts(child, /* base = */ NULL, cfg.size,
+                child->bts = ds_request_bts(child, child->bts_buffer, cfg.size,
                                             ovfl, /* th = */ (size_t)-1);
                 if (IS_ERR(child->bts)) {
                         error = PTR_ERR(child->bts);
+                        kfree(child->bts_buffer);
                         child->bts = NULL;
+                        child->bts_buffer = NULL;
                         goto errout;
                 }
 
@@ -972,6 +988,8 @@ void ptrace_disable(struct task_struct *child)
 #ifdef CONFIG_X86_PTRACE_BTS
         if (child->bts) {
                 (void)ds_release_bts(child->bts);
+                kfree(child->bts_buffer);
+                child->bts_buffer = NULL;
 
                 child->thread.debugctlmsr &= ~bts_cfg.debugctl_mask;
                 if (!child->thread.debugctlmsr)