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Diffstat (limited to 'arch/x86/kernel/process_64.c')
-rw-r--r--arch/x86/kernel/process_64.c197
1 files changed, 152 insertions, 45 deletions
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index a451bc374b9b..31b4755369f0 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));
@@ -278,6 +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)
{
@@ -465,10 +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);
@@ -619,54 +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;
}
generated by cgit v1.2.3 (git 2.39.0) at 2024-11-15 08:34:15 +0300