diff options
Diffstat (limited to 'arch/x86/kernel/process_64.c')
| -rw-r--r-- | arch/x86/kernel/process_64.c | 109 |
1 files changed, 58 insertions, 51 deletions
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index 0e0b4288a4b2..ddd4fa718c43 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -60,6 +60,8 @@ #include <asm/unistd_32_ia32.h> #endif +#include "process.h" + /* Prints also some state that isn't saved in the pt_regs */ void __show_regs(struct pt_regs *regs, enum show_regs_mode mode) { @@ -337,24 +339,6 @@ static unsigned long x86_fsgsbase_read_task(struct task_struct *task, return base; } -void x86_fsbase_write_cpu(unsigned long fsbase) -{ - /* - * Set the selector to 0 as a notion, that the segment base is - * overwritten, which will be checked for skipping the segment load - * during context switch. - */ - loadseg(FS, 0); - wrmsrl(MSR_FS_BASE, fsbase); -} - -void x86_gsbase_write_cpu_inactive(unsigned long gsbase) -{ - /* Set the selector to 0 for the same reason as %fs above. */ - loadseg(GS, 0); - wrmsrl(MSR_KERNEL_GS_BASE, gsbase); -} - unsigned long x86_fsbase_read_task(struct task_struct *task) { unsigned long fsbase; @@ -383,38 +367,18 @@ unsigned long x86_gsbase_read_task(struct task_struct *task) return gsbase; } -int x86_fsbase_write_task(struct task_struct *task, unsigned long fsbase) +void x86_fsbase_write_task(struct task_struct *task, unsigned long fsbase) { - /* - * Not strictly needed for %fs, but do it for symmetry - * with %gs - */ - if (unlikely(fsbase >= TASK_SIZE_MAX)) - return -EPERM; + WARN_ON_ONCE(task == current); - preempt_disable(); task->thread.fsbase = fsbase; - if (task == current) - x86_fsbase_write_cpu(fsbase); - task->thread.fsindex = 0; - preempt_enable(); - - return 0; } -int x86_gsbase_write_task(struct task_struct *task, unsigned long gsbase) +void x86_gsbase_write_task(struct task_struct *task, unsigned long gsbase) { - if (unlikely(gsbase >= TASK_SIZE_MAX)) - return -EPERM; + WARN_ON_ONCE(task == current); - preempt_disable(); task->thread.gsbase = gsbase; - if (task == current) - x86_gsbase_write_cpu_inactive(gsbase); - task->thread.gsindex = 0; - preempt_enable(); - - return 0; } int copy_thread_tls(unsigned long clone_flags, unsigned long sp, @@ -553,7 +517,6 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p) struct fpu *prev_fpu = &prev->fpu; struct fpu *next_fpu = &next->fpu; int cpu = smp_processor_id(); - struct tss_struct *tss = &per_cpu(cpu_tss_rw, cpu); WARN_ON_ONCE(IS_ENABLED(CONFIG_DEBUG_ENTRY) && this_cpu_read(irq_count) != -1); @@ -617,12 +580,7 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p) /* Reload sp0. */ update_task_stack(next_p); - /* - * Now maybe reload the debug registers and handle I/O bitmaps - */ - if (unlikely(task_thread_info(next_p)->flags & _TIF_WORK_CTXSW_NEXT || - task_thread_info(prev_p)->flags & _TIF_WORK_CTXSW_PREV)) - __switch_to_xtra(prev_p, next_p, tss); + switch_to_extra(prev_p, next_p); #ifdef CONFIG_XEN_PV /* @@ -758,11 +716,60 @@ long do_arch_prctl_64(struct task_struct *task, int option, unsigned long arg2) switch (option) { case ARCH_SET_GS: { - ret = x86_gsbase_write_task(task, arg2); + if (unlikely(arg2 >= TASK_SIZE_MAX)) + return -EPERM; + + preempt_disable(); + /* + * ARCH_SET_GS has always overwritten the index + * and the base. Zero is the most sensible value + * to put in the index, and is the only value that + * makes any sense if FSGSBASE is unavailable. + */ + if (task == current) { + loadseg(GS, 0); + x86_gsbase_write_cpu_inactive(arg2); + + /* + * On non-FSGSBASE systems, save_base_legacy() expects + * that we also fill in thread.gsbase. + */ + task->thread.gsbase = arg2; + + } else { + task->thread.gsindex = 0; + x86_gsbase_write_task(task, arg2); + } + preempt_enable(); break; } case ARCH_SET_FS: { - ret = x86_fsbase_write_task(task, arg2); + /* + * Not strictly needed for %fs, but do it for symmetry + * with %gs + */ + if (unlikely(arg2 >= TASK_SIZE_MAX)) + return -EPERM; + + preempt_disable(); + /* + * Set the selector to 0 for the same reason + * as %gs above. + */ + if (task == current) { + loadseg(FS, 0); + x86_fsbase_write_cpu(arg2); + + /* + * On non-FSGSBASE systems, save_base_legacy() expects + * that we also fill in thread.fsbase. + */ + task->thread.fsbase = arg2; + } else { + task->thread.fsindex = 0; + x86_fsbase_write_task(task, arg2); + } + preempt_enable(); break; } case ARCH_GET_FS: { |