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Message-Id: <20071125220819.B7D4726F8C5@magilla.localdomain>
Date: Sun, 25 Nov 2007 14:08:19 -0800 (PST)
From: Roland McGrath <roland@...hat.com>
To: Andrew Morton <akpm@...ux-foundation.org>,
Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...e.hu>,
"H. Peter Anvin" <hpa@...or.com>
Subject: [PATCH 24/27] x86: debugctlmsr context switch
This adds low-level support for a per-thread value of MSR_IA32_DEBUGCTLMSR.
The per-thread value is switched in when TIF_DEBUGCTLMSR is set.
Signed-off-by: Roland McGrath <roland@...hat.com>
---
arch/x86/kernel/process_32.c | 6 +++++-
arch/x86/kernel/process_64.c | 3 +++
include/asm-x86/processor_32.h | 2 ++
include/asm-x86/processor_64.h | 2 ++
include/asm-x86/thread_info_32.h | 6 ++++--
include/asm-x86/thread_info_64.h | 4 +++-
6 files changed, 19 insertions(+), 4 deletions(-)
diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
index f59544e..3a822e3 100644
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -581,10 +581,14 @@ static noinline void
__switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p,
struct tss_struct *tss)
{
- struct thread_struct *next;
+ struct thread_struct *prev, *next;
+ prev = &prev_p->thread;
next = &next_p->thread;
+ if (next->debugctlmsr != prev->debugctlmsr)
+ wrmsr(MSR_IA32_DEBUGCTLMSR, next->debugctlmsr, 0);
+
if (test_tsk_thread_flag(next_p, TIF_DEBUG)) {
set_debugreg(next->debugreg[0], 0);
set_debugreg(next->debugreg[1], 1);
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index 586f88e..c1e2e9a 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -544,6 +544,9 @@ static inline void __switch_to_xtra(struct task_struct *prev_p,
prev = &prev_p->thread,
next = &next_p->thread;
+ if (next->debugctlmsr != prev->debugctlmsr)
+ wrmsrl(MSR_IA32_DEBUGCTLMSR, next->debugctlmsr);
+
if (test_tsk_thread_flag(next_p, TIF_DEBUG)) {
loaddebug(next, 0);
loaddebug(next, 1);
diff --git a/include/asm-x86/processor_32.h b/include/asm-x86/processor_32.h
index 34e8063..660d9b0 100644
--- a/include/asm-x86/processor_32.h
+++ b/include/asm-x86/processor_32.h
@@ -370,6 +370,8 @@ struct thread_struct {
unsigned long iopl;
/* max allowed port in the bitmap, in bytes: */
unsigned long io_bitmap_max;
+/* MSR_IA32_DEBUGCTLMSR value to switch in if TIF_DEBUGCTLMSR is set. */
+ unsigned long debugctlmsr;
};
#define INIT_THREAD { \
diff --git a/include/asm-x86/processor_64.h b/include/asm-x86/processor_64.h
index 2dd739a..1d6daa0 100644
--- a/include/asm-x86/processor_64.h
+++ b/include/asm-x86/processor_64.h
@@ -239,6 +239,8 @@ struct thread_struct {
int ioperm;
unsigned long *io_bitmap_ptr;
unsigned io_bitmap_max;
+/* MSR_IA32_DEBUGCTLMSR value to switch in if TIF_DEBUGCTLMSR is set. */
+ unsigned long debugctlmsr;
/* cached TLS descriptors. */
u64 tls_array[GDT_ENTRY_TLS_ENTRIES];
} __attribute__((aligned(16)));
diff --git a/include/asm-x86/thread_info_32.h b/include/asm-x86/thread_info_32.h
index 8a6483f..d5ae1e9 100644
--- a/include/asm-x86/thread_info_32.h
+++ b/include/asm-x86/thread_info_32.h
@@ -138,6 +138,7 @@ static inline struct thread_info *current_thread_info(void)
#define TIF_FREEZE 19 /* is freezing for suspend */
#define TIF_NOTSC 20 /* TSC is not accessible in userland */
#define TIF_FORCED_TF 21 /* true if TF in eflags artificially */
+#define TIF_DEBUGCTLMSR 22 /* uses thread_struct.debugctlmsr */
#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
#define _TIF_SIGPENDING (1<<TIF_SIGPENDING)
@@ -153,6 +154,7 @@ static inline struct thread_info *current_thread_info(void)
#define _TIF_FREEZE (1<<TIF_FREEZE)
#define _TIF_NOTSC (1<<TIF_NOTSC)
#define _TIF_FORCED_TF (1<<TIF_FORCED_TF)
+#define _TIF_DEBUGCTLMSR (1<<TIF_DEBUGCTLMSR)
/* work to do on interrupt/exception return */
#define _TIF_WORK_MASK \
@@ -162,8 +164,8 @@ static inline struct thread_info *current_thread_info(void)
#define _TIF_ALLWORK_MASK (0x0000FFFF & ~_TIF_SECCOMP)
/* flags to check in __switch_to() */
-#define _TIF_WORK_CTXSW_NEXT (_TIF_IO_BITMAP | _TIF_NOTSC | _TIF_DEBUG)
-#define _TIF_WORK_CTXSW_PREV (_TIF_IO_BITMAP | _TIF_NOTSC)
+#define _TIF_WORK_CTXSW_NEXT (_TIF_IO_BITMAP | _TIF_NOTSC | _TIF_DEBUG | _TIF_DEBUGCTLMSR)
+#define _TIF_WORK_CTXSW_PREV (_TIF_IO_BITMAP | _TIF_NOTSC | _TIF_DEBUGCTLMSR)
/*
* Thread-synchronous status.
diff --git a/include/asm-x86/thread_info_64.h b/include/asm-x86/thread_info_64.h
index 0ebcac4..8f36bbc 100644
--- a/include/asm-x86/thread_info_64.h
+++ b/include/asm-x86/thread_info_64.h
@@ -123,6 +123,7 @@ static inline struct thread_info *stack_thread_info(void)
#define TIF_DEBUG 21 /* uses debug registers */
#define TIF_IO_BITMAP 22 /* uses I/O bitmap */
#define TIF_FREEZE 23 /* is freezing for suspend */
+#define TIF_DEBUGCTLMSR 24 /* uses thread_struct.debugctlmsr */
#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
#define _TIF_SIGPENDING (1<<TIF_SIGPENDING)
@@ -140,6 +141,7 @@ static inline struct thread_info *stack_thread_info(void)
#define _TIF_DEBUG (1<<TIF_DEBUG)
#define _TIF_IO_BITMAP (1<<TIF_IO_BITMAP)
#define _TIF_FREEZE (1<<TIF_FREEZE)
+#define _TIF_DEBUGCTLMSR (1<<TIF_DEBUGCTLMSR)
/* work to do on interrupt/exception return */
#define _TIF_WORK_MASK \
@@ -148,7 +150,7 @@ static inline struct thread_info *stack_thread_info(void)
#define _TIF_ALLWORK_MASK (0x0000FFFF & ~_TIF_SECCOMP)
/* flags to check in __switch_to() */
-#define _TIF_WORK_CTXSW (_TIF_DEBUG|_TIF_IO_BITMAP)
+#define _TIF_WORK_CTXSW (_TIF_DEBUG|_TIF_IO_BITMAP|_TIF_DEBUGCTLMSR)
#define PREEMPT_ACTIVE 0x10000000
-
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