x86/split-lock: Remove unused TIF_SLD bit

Changes to the "warn" mode of split lock handling mean that TIF_SLD is
never set.

Remove the bit, and the functions that use it.

Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20220310204854.31752-3-tony.luck@intel.com

diff --git a/arch/x86/include/asm/cpu.h b/arch/x86/include/asm/cpu.h
index 86e5e4e26fcbefc68c961d9395e163f6d840a878..d1c86b221bb97b3bd64d4ef7658488f1a5362530 100644 (file)
--- a/arch/x86/include/asm/cpu.h
+++ b/arch/x86/include/asm/cpu.h
@@ -43,14 +43,12 @@ unsigned int x86_model(unsigned int sig);
 unsigned int x86_stepping(unsigned int sig);
 #ifdef CONFIG_CPU_SUP_INTEL
 extern void __init sld_setup(struct cpuinfo_x86 *c);
-extern void switch_to_sld(unsigned long tifn);
 extern bool handle_user_split_lock(struct pt_regs *regs, long error_code);
 extern bool handle_guest_split_lock(unsigned long ip);
 extern void handle_bus_lock(struct pt_regs *regs);
 u8 get_this_hybrid_cpu_type(void);
 #else
 static inline void __init sld_setup(struct cpuinfo_x86 *c) {}
-static inline void switch_to_sld(unsigned long tifn) {}
 static inline bool handle_user_split_lock(struct pt_regs *regs, long error_code)
 {
        return false;

diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h
index ebec69c35e951c721d2640d74610cc29f2e8fbff..f0cb881c1d690859feac72cc92afdd9abe9d0b3a 100644 (file)
--- a/arch/x86/include/asm/thread_info.h
+++ b/arch/x86/include/asm/thread_info.h
@@ -92,7 +92,6 @@ struct thread_info {
 #define TIF_NOCPUID            15      /* CPUID is not accessible in userland */
 #define TIF_NOTSC              16      /* TSC is not accessible in userland */
 #define TIF_NOTIFY_SIGNAL      17      /* signal notifications exist */
-#define TIF_SLD                        18      /* Restore split lock detection on context switch */
 #define TIF_MEMDIE             20      /* is terminating due to OOM killer */
 #define TIF_POLLING_NRFLAG     21      /* idle is polling for TIF_NEED_RESCHED */
 #define TIF_IO_BITMAP          22      /* uses I/O bitmap */
@@ -116,7 +115,6 @@ struct thread_info {
 #define _TIF_NOCPUID           (1 << TIF_NOCPUID)
 #define _TIF_NOTSC             (1 << TIF_NOTSC)
 #define _TIF_NOTIFY_SIGNAL     (1 << TIF_NOTIFY_SIGNAL)
-#define _TIF_SLD               (1 << TIF_SLD)
 #define _TIF_POLLING_NRFLAG    (1 << TIF_POLLING_NRFLAG)
 #define _TIF_IO_BITMAP         (1 << TIF_IO_BITMAP)
 #define _TIF_SPEC_FORCE_UPDATE (1 << TIF_SPEC_FORCE_UPDATE)
@@ -128,7 +126,7 @@ struct thread_info {
 /* flags to check in __switch_to() */
 #define _TIF_WORK_CTXSW_BASE                                   \
        (_TIF_NOCPUID | _TIF_NOTSC | _TIF_BLOCKSTEP |           \
-        _TIF_SSBD | _TIF_SPEC_FORCE_UPDATE | _TIF_SLD)
+        _TIF_SSBD | _TIF_SPEC_FORCE_UPDATE)
 
 /*
  * Avoid calls to __switch_to_xtra() on UP as STIBP is not evaluated.

diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
index be2a0bdb9527d106a996e74b302b587f9efccac4..672e253a58b95a11fb0f85104420a6fa6fdfaba9 100644 (file)
--- a/arch/x86/kernel/cpu/intel.c
+++ b/arch/x86/kernel/cpu/intel.c
@@ -1232,18 +1232,6 @@ void handle_bus_lock(struct pt_regs *regs)
        }
 }
 
-/*
- * This function is called only when switching between tasks with
- * different split-lock detection modes. It sets the MSR for the
- * mode of the new task. This is right most of the time, but since
- * the MSR is shared by hyperthreads on a physical core there can
- * be glitches when the two threads need different modes.
- */
-void switch_to_sld(unsigned long tifn)
-{
-       sld_update_msr(!(tifn & _TIF_SLD));
-}
-
 /*
  * Bits in the IA32_CORE_CAPABILITIES are not architectural, so they should
  * only be trusted if it is confirmed that a CPU model implements a

diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index b370767f5b191e1556b3665a3b8b5f032decf0e6..bcc76c187e11b751eeff6f5ac7ed7384b54efbb5 100644 (file)
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -686,9 +686,6 @@ void __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p)
                /* Enforce MSR update to ensure consistent state */
                __speculation_ctrl_update(~tifn, tifn);
        }
-
-       if ((tifp ^ tifn) & _TIF_SLD)
-               switch_to_sld(tifn);
 }
 
 /*