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x86/split-lock: Remove unused TIF_SLD bit

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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
This commit is contained in:
Tony Luck 2022-03-10 12:48:54 -08:00 committed by Thomas Gleixner
parent b041b525da
commit ef79970d7c
4 changed files with 1 additions and 20 deletions
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2
arch/x86/include/asm/cpu.h
View File

@ -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;

4
arch/x86/include/asm/thread_info.h
View File

@ -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.

12
arch/x86/kernel/cpu/intel.c
View File

@ -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

3
arch/x86/kernel/process.c
View File

@ -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);
}
/*