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-rw-r--r--arch/x86/kernel/process_32.c43
-rw-r--r--arch/x86/kernel/process_64.c68
-rw-r--r--include/asm-x86/processor.h7
-rw-r--r--include/asm-x86/thread_info_64.h4
-rw-r--r--include/asm-x86/tsc.h1
5 files changed, 118 insertions, 5 deletions
diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
index 91e147b486d..a3790a3f8a8 100644
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -36,6 +36,7 @@
#include <linux/personality.h>
#include <linux/tick.h>
#include <linux/percpu.h>
+#include <linux/prctl.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
@@ -523,11 +524,11 @@ start_thread(struct pt_regs *regs, unsigned long new_ip, unsigned long new_sp)
}
EXPORT_SYMBOL_GPL(start_thread);
-#ifdef CONFIG_SECCOMP
static void hard_disable_TSC(void)
{
write_cr4(read_cr4() | X86_CR4_TSD);
}
+
void disable_TSC(void)
{
preempt_disable();
@@ -539,11 +540,47 @@ void disable_TSC(void)
hard_disable_TSC();
preempt_enable();
}
+
static void hard_enable_TSC(void)
{
write_cr4(read_cr4() & ~X86_CR4_TSD);
}
-#endif /* CONFIG_SECCOMP */
+
+void enable_TSC(void)
+{
+ preempt_disable();
+ if (test_and_clear_thread_flag(TIF_NOTSC))
+ /*
+ * Must flip the CPU state synchronously with
+ * TIF_NOTSC in the current running context.
+ */
+ hard_enable_TSC();
+ preempt_enable();
+}
+
+int get_tsc_mode(unsigned long adr)
+{
+ unsigned int val;
+
+ if (test_thread_flag(TIF_NOTSC))
+ val = PR_TSC_SIGSEGV;
+ else
+ val = PR_TSC_ENABLE;
+
+ return put_user(val, (unsigned int __user *)adr);
+}
+
+int set_tsc_mode(unsigned int val)
+{
+ if (val == PR_TSC_SIGSEGV)
+ disable_TSC();
+ else if (val == PR_TSC_ENABLE)
+ enable_TSC();
+ else
+ return -EINVAL;
+
+ return 0;
+}
static noinline void
__switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p,
@@ -577,7 +614,6 @@ __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p,
set_debugreg(next->debugreg7, 7);
}
-#ifdef CONFIG_SECCOMP
if (test_tsk_thread_flag(prev_p, TIF_NOTSC) ^
test_tsk_thread_flag(next_p, TIF_NOTSC)) {
/* prev and next are different */
@@ -586,7 +622,6 @@ __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p,
else
hard_enable_TSC();
}
-#endif
#ifdef X86_BTS
if (test_tsk_thread_flag(prev_p, TIF_BTS_TRACE_TS))
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index e75ccc8a2b8..4c13b1406c7 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -36,6 +36,7 @@
#include <linux/kprobes.h>
#include <linux/kdebug.h>
#include <linux/tick.h>
+#include <linux/prctl.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
@@ -535,6 +536,64 @@ start_thread(struct pt_regs *regs, unsigned long new_ip, unsigned long new_sp)
}
EXPORT_SYMBOL_GPL(start_thread);
+static void hard_disable_TSC(void)
+{
+ write_cr4(read_cr4() | X86_CR4_TSD);
+}
+
+void disable_TSC(void)
+{
+ preempt_disable();
+ if (!test_and_set_thread_flag(TIF_NOTSC))
+ /*
+ * Must flip the CPU state synchronously with
+ * TIF_NOTSC in the current running context.
+ */
+ hard_disable_TSC();
+ preempt_enable();
+}
+
+static void hard_enable_TSC(void)
+{
+ write_cr4(read_cr4() & ~X86_CR4_TSD);
+}
+
+void enable_TSC(void)
+{
+ preempt_disable();
+ if (test_and_clear_thread_flag(TIF_NOTSC))
+ /*
+ * Must flip the CPU state synchronously with
+ * TIF_NOTSC in the current running context.
+ */
+ hard_enable_TSC();
+ preempt_enable();
+}
+
+int get_tsc_mode(unsigned long adr)
+{
+ unsigned int val;
+
+ if (test_thread_flag(TIF_NOTSC))
+ val = PR_TSC_SIGSEGV;
+ else
+ val = PR_TSC_ENABLE;
+
+ return put_user(val, (unsigned int __user *)adr);
+}
+
+int set_tsc_mode(unsigned int val)
+{
+ if (val == PR_TSC_SIGSEGV)
+ disable_TSC();
+ else if (val == PR_TSC_ENABLE)
+ enable_TSC();
+ else
+ return -EINVAL;
+
+ return 0;
+}
+
/*
* This special macro can be used to load a debugging register
*/
@@ -572,6 +631,15 @@ static inline void __switch_to_xtra(struct task_struct *prev_p,
loaddebug(next, 7);
}
+ if (test_tsk_thread_flag(prev_p, TIF_NOTSC) ^
+ test_tsk_thread_flag(next_p, TIF_NOTSC)) {
+ /* prev and next are different */
+ if (test_tsk_thread_flag(next_p, TIF_NOTSC))
+ hard_disable_TSC();
+ else
+ hard_enable_TSC();
+ }
+
if (test_tsk_thread_flag(next_p, TIF_IO_BITMAP)) {
/*
* Copy the relevant range of the IO bitmap.
diff --git a/include/asm-x86/processor.h b/include/asm-x86/processor.h
index 6e26c7c717a..eaf4548a23d 100644
--- a/include/asm-x86/processor.h
+++ b/include/asm-x86/processor.h
@@ -918,4 +918,11 @@ extern void start_thread(struct pt_regs *regs, unsigned long new_ip,
#define KSTK_EIP(task) (task_pt_regs(task)->ip)
+/* Get/set a process' ability to use the timestamp counter instruction */
+#define GET_TSC_CTL(adr) get_tsc_mode((adr))
+#define SET_TSC_CTL(val) set_tsc_mode((val))
+
+extern int get_tsc_mode(unsigned long adr);
+extern int set_tsc_mode(unsigned int val);
+
#endif
diff --git a/include/asm-x86/thread_info_64.h b/include/asm-x86/thread_info_64.h
index 1e5c6f6152c..b17f5f6c2c5 100644
--- a/include/asm-x86/thread_info_64.h
+++ b/include/asm-x86/thread_info_64.h
@@ -126,6 +126,7 @@ static inline struct thread_info *stack_thread_info(void)
#define TIF_DEBUGCTLMSR 25 /* uses thread_struct.debugctlmsr */
#define TIF_DS_AREA_MSR 26 /* uses thread_struct.ds_area_msr */
#define TIF_BTS_TRACE_TS 27 /* record scheduling event timestamps */
+#define TIF_NOTSC 28 /* TSC is not accessible in userland */
#define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)
#define _TIF_SIGPENDING (1 << TIF_SIGPENDING)
@@ -147,6 +148,7 @@ static inline struct thread_info *stack_thread_info(void)
#define _TIF_DEBUGCTLMSR (1 << TIF_DEBUGCTLMSR)
#define _TIF_DS_AREA_MSR (1 << TIF_DS_AREA_MSR)
#define _TIF_BTS_TRACE_TS (1 << TIF_BTS_TRACE_TS)
+#define _TIF_NOTSC (1 << TIF_NOTSC)
/* work to do on interrupt/exception return */
#define _TIF_WORK_MASK \
@@ -160,7 +162,7 @@ static inline struct thread_info *stack_thread_info(void)
/* flags to check in __switch_to() */
#define _TIF_WORK_CTXSW \
- (_TIF_IO_BITMAP|_TIF_DEBUGCTLMSR|_TIF_DS_AREA_MSR|_TIF_BTS_TRACE_TS)
+ (_TIF_IO_BITMAP|_TIF_DEBUGCTLMSR|_TIF_DS_AREA_MSR|_TIF_BTS_TRACE_TS|_TIF_NOTSC)
#define _TIF_WORK_CTXSW_PREV _TIF_WORK_CTXSW
#define _TIF_WORK_CTXSW_NEXT (_TIF_WORK_CTXSW|_TIF_DEBUG)
diff --git a/include/asm-x86/tsc.h b/include/asm-x86/tsc.h
index d2d8eb5b55f..0434bd8349a 100644
--- a/include/asm-x86/tsc.h
+++ b/include/asm-x86/tsc.h
@@ -18,6 +18,7 @@ extern unsigned int cpu_khz;
extern unsigned int tsc_khz;
extern void disable_TSC(void);
+extern void enable_TSC(void);
static inline cycles_t get_cycles(void)
{
generated by cgit v1.2.3-70-g09d2 (git 2.46.0) at 2024-12-18 01:51:44 +0000