x86, bts: provide in-kernel branch-trace interface

Impact: cleanup

Move the BTS bits from ptrace.c into ds.c.

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

1 files changed, 12 insertions, 38 deletions

diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index fbb321d53d34..1cfd2a4bf853 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -237,11 +237,14 @@ void exit_thread(void)
                 put_cpu();
         }
 #ifdef CONFIG_X86_DS
-        /* Free any DS contexts that have not been properly released. */
-        if (unlikely(t->ds_ctx)) {
-                /* we clear debugctl to make sure DS is not used. */
-                update_debugctlmsr(0);
-                ds_free(t->ds_ctx);
+        /* Free any BTS tracers that have not been properly released. */
+        if (unlikely(current->bts)) {
+                ds_release_bts(current->bts);
+                current->bts = NULL;
+
+                kfree(current->bts_buffer);
+                current->bts_buffer = NULL;
+                current->bts_size = 0;
         }
 #endif /* CONFIG_X86_DS */
 }
@@ -471,35 +474,14 @@ static inline void __switch_to_xtra(struct task_struct *prev_p,
                                     struct tss_struct *tss)
 {
         struct thread_struct *prev, *next;
-        unsigned long debugctl;
 
         prev = &prev_p->thread,
         next = &next_p->thread;
 
-        debugctl = prev->debugctlmsr;
-
-#ifdef CONFIG_X86_DS
-        {
-                unsigned long ds_prev = 0, ds_next = 0;
-
-                if (prev->ds_ctx)
-                        ds_prev = (unsigned long)prev->ds_ctx->ds;
-                if (next->ds_ctx)
-                        ds_next = (unsigned long)next->ds_ctx->ds;
-
-                if (ds_next != ds_prev) {
-                        /*
-                         * We clear debugctl to make sure DS
-                         * is not in use when we change it:
-                         */
-                        debugctl = 0;
-                        update_debugctlmsr(0);
-                        wrmsrl(MSR_IA32_DS_AREA, ds_next);
-                }
-        }
-#endif /* CONFIG_X86_DS */
-
-        if (next->debugctlmsr != debugctl)
+        if (test_tsk_thread_flag(next_p, TIF_DS_AREA_MSR) ||
+            test_tsk_thread_flag(prev_p, TIF_DS_AREA_MSR))
+                ds_switch_to(prev_p, next_p);
+        else if (next->debugctlmsr != prev->debugctlmsr)
                 update_debugctlmsr(next->debugctlmsr);
 
         if (test_tsk_thread_flag(next_p, TIF_DEBUG)) {
@@ -534,14 +516,6 @@ static inline void __switch_to_xtra(struct task_struct *prev_p,
                  */
                 memset(tss->io_bitmap, 0xff, prev->io_bitmap_max);
         }
-
-#ifdef CONFIG_X86_PTRACE_BTS
-        if (test_tsk_thread_flag(prev_p, TIF_BTS_TRACE_TS))
-                ptrace_bts_take_timestamp(prev_p, BTS_TASK_DEPARTS);
-
-        if (test_tsk_thread_flag(next_p, TIF_BTS_TRACE_TS))
-                ptrace_bts_take_timestamp(next_p, BTS_TASK_ARRIVES);
-#endif /* CONFIG_X86_PTRACE_BTS */
 }
 
 /*