diff options
Diffstat (limited to 'arch/x86/kernel/process_64.c')
-rw-r--r-- | arch/x86/kernel/process_64.c | 219 |
1 files changed, 171 insertions, 48 deletions
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index 9eb448c7859d..0e0b4288a4b2 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -54,15 +54,14 @@ #include <asm/vdso.h> #include <asm/intel_rdt_sched.h> #include <asm/unistd.h> +#include <asm/fsgsbase.h> #ifdef CONFIG_IA32_EMULATION /* Not included via unistd.h */ #include <asm/unistd_32_ia32.h> #endif -__visible DEFINE_PER_CPU(unsigned long, rsp_scratch); - /* Prints also some state that isn't saved in the pt_regs */ -void __show_regs(struct pt_regs *regs, int all) +void __show_regs(struct pt_regs *regs, enum show_regs_mode mode) { unsigned long cr0 = 0L, cr2 = 0L, cr3 = 0L, cr4 = 0L, fs, gs, shadowgs; unsigned long d0, d1, d2, d3, d6, d7; @@ -87,9 +86,17 @@ void __show_regs(struct pt_regs *regs, int all) printk(KERN_DEFAULT "R13: %016lx R14: %016lx R15: %016lx\n", regs->r13, regs->r14, regs->r15); - if (!all) + if (mode == SHOW_REGS_SHORT) return; + if (mode == SHOW_REGS_USER) { + rdmsrl(MSR_FS_BASE, fs); + rdmsrl(MSR_KERNEL_GS_BASE, shadowgs); + printk(KERN_DEFAULT "FS: %016lx GS: %016lx\n", + fs, shadowgs); + return; + } + asm("movl %%ds,%0" : "=r" (ds)); asm("movl %%cs,%0" : "=r" (cs)); asm("movl %%es,%0" : "=r" (es)); @@ -205,6 +212,20 @@ static __always_inline void save_fsgs(struct task_struct *task) save_base_legacy(task, task->thread.gsindex, GS); } +#if IS_ENABLED(CONFIG_KVM) +/* + * While a process is running,current->thread.fsbase and current->thread.gsbase + * may not match the corresponding CPU registers (see save_base_legacy()). KVM + * wants an efficient way to save and restore FSBASE and GSBASE. + * When FSGSBASE extensions are enabled, this will have to use RD{FS,GS}BASE. + */ +void save_fsgs_for_kvm(void) +{ + save_fsgs(current); +} +EXPORT_SYMBOL_GPL(save_fsgs_for_kvm); +#endif + static __always_inline void loadseg(enum which_selector which, unsigned short sel) { @@ -264,6 +285,138 @@ static __always_inline void load_seg_legacy(unsigned short prev_index, } } +static __always_inline void x86_fsgsbase_load(struct thread_struct *prev, + struct thread_struct *next) +{ + load_seg_legacy(prev->fsindex, prev->fsbase, + next->fsindex, next->fsbase, FS); + load_seg_legacy(prev->gsindex, prev->gsbase, + next->gsindex, next->gsbase, GS); +} + +static unsigned long x86_fsgsbase_read_task(struct task_struct *task, + unsigned short selector) +{ + unsigned short idx = selector >> 3; + unsigned long base; + + if (likely((selector & SEGMENT_TI_MASK) == 0)) { + if (unlikely(idx >= GDT_ENTRIES)) + return 0; + + /* + * There are no user segments in the GDT with nonzero bases + * other than the TLS segments. + */ + if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX) + return 0; + + idx -= GDT_ENTRY_TLS_MIN; + base = get_desc_base(&task->thread.tls_array[idx]); + } else { +#ifdef CONFIG_MODIFY_LDT_SYSCALL + struct ldt_struct *ldt; + + /* + * If performance here mattered, we could protect the LDT + * with RCU. This is a slow path, though, so we can just + * take the mutex. + */ + mutex_lock(&task->mm->context.lock); + ldt = task->mm->context.ldt; + if (unlikely(idx >= ldt->nr_entries)) + base = 0; + else + base = get_desc_base(ldt->entries + idx); + mutex_unlock(&task->mm->context.lock); +#else + base = 0; +#endif + } + + 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; + + if (task == current) + fsbase = x86_fsbase_read_cpu(); + else if (task->thread.fsindex == 0) + fsbase = task->thread.fsbase; + else + fsbase = x86_fsgsbase_read_task(task, task->thread.fsindex); + + return fsbase; +} + +unsigned long x86_gsbase_read_task(struct task_struct *task) +{ + unsigned long gsbase; + + if (task == current) + gsbase = x86_gsbase_read_cpu_inactive(); + else if (task->thread.gsindex == 0) + gsbase = task->thread.gsbase; + else + gsbase = x86_fsgsbase_read_task(task, task->thread.gsindex); + + return gsbase; +} + +int 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; + + 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) +{ + if (unlikely(gsbase >= TASK_SIZE_MAX)) + return -EPERM; + + 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, unsigned long arg, struct task_struct *p, unsigned long tls) { @@ -370,6 +523,7 @@ start_thread(struct pt_regs *regs, unsigned long new_ip, unsigned long new_sp) start_thread_common(regs, new_ip, new_sp, __USER_CS, __USER_DS, 0); } +EXPORT_SYMBOL_GPL(start_thread); #ifdef CONFIG_COMPAT void compat_start_thread(struct pt_regs *regs, u32 new_ip, u32 new_sp) @@ -450,10 +604,7 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p) if (unlikely(next->ds | prev->ds)) loadsegment(ds, next->ds); - load_seg_legacy(prev->fsindex, prev->fsbase, - next->fsindex, next->fsbase, FS); - load_seg_legacy(prev->gsindex, prev->gsbase, - next->gsindex, next->gsbase, GS); + x86_fsgsbase_load(prev, next); switch_fpu_finish(next_fpu, cpu); @@ -464,7 +615,7 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p) this_cpu_write(cpu_current_top_of_stack, task_top_of_stack(next_p)); /* Reload sp0. */ - update_sp0(next_p); + update_task_stack(next_p); /* * Now maybe reload the debug registers and handle I/O bitmaps @@ -528,6 +679,7 @@ void set_personality_64bit(void) clear_thread_flag(TIF_X32); /* Pretend that this comes from a 64bit execve */ task_pt_regs(current)->orig_ax = __NR_execve; + current_thread_info()->status &= ~TS_COMPAT; /* Ensure the corresponding mm is not marked. */ if (current->mm) @@ -549,10 +701,10 @@ static void __set_personality_x32(void) current->mm->context.ia32_compat = TIF_X32; current->personality &= ~READ_IMPLIES_EXEC; /* - * in_compat_syscall() uses the presence of the x32 syscall bit + * in_32bit_syscall() uses the presence of the x32 syscall bit * flag to determine compat status. The x86 mmap() code relies on * the syscall bitness so set x32 syscall bit right here to make - * in_compat_syscall() work during exec(). + * in_32bit_syscall() work during exec(). * * Pretend to come from a x32 execve. */ @@ -603,54 +755,25 @@ static long prctl_map_vdso(const struct vdso_image *image, unsigned long addr) long do_arch_prctl_64(struct task_struct *task, int option, unsigned long arg2) { int ret = 0; - int doit = task == current; - int cpu; switch (option) { - case ARCH_SET_GS: - if (arg2 >= TASK_SIZE_MAX) - return -EPERM; - cpu = get_cpu(); - task->thread.gsindex = 0; - task->thread.gsbase = arg2; - if (doit) { - load_gs_index(0); - ret = wrmsrl_safe(MSR_KERNEL_GS_BASE, arg2); - } - put_cpu(); + case ARCH_SET_GS: { + ret = x86_gsbase_write_task(task, arg2); break; - case ARCH_SET_FS: - /* Not strictly needed for fs, but do it for symmetry - with gs */ - if (arg2 >= TASK_SIZE_MAX) - return -EPERM; - cpu = get_cpu(); - task->thread.fsindex = 0; - task->thread.fsbase = arg2; - if (doit) { - /* set the selector to 0 to not confuse __switch_to */ - loadsegment(fs, 0); - ret = wrmsrl_safe(MSR_FS_BASE, arg2); - } - put_cpu(); + } + case ARCH_SET_FS: { + ret = x86_fsbase_write_task(task, arg2); break; + } case ARCH_GET_FS: { - unsigned long base; + unsigned long base = x86_fsbase_read_task(task); - if (doit) - rdmsrl(MSR_FS_BASE, base); - else - base = task->thread.fsbase; ret = put_user(base, (unsigned long __user *)arg2); break; } case ARCH_GET_GS: { - unsigned long base; + unsigned long base = x86_gsbase_read_task(task); - if (doit) - rdmsrl(MSR_KERNEL_GS_BASE, base); - else - base = task->thread.gsbase; ret = put_user(base, (unsigned long __user *)arg2); break; } |