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x86/asm/64: Rename thread_struct's fs and gs to fsbase and gsbase

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Unlike ds and es, these are base addresses, not selectors.  Rename
them so their meaning is more obvious.

On x86_32, the field is still called fs.  Fixing that could make sense
as a future cleanup.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/69a18a51c4cba0ce29a241e570fc618ad721d908.1461698311.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Andy Lutomirski 2016-04-26 12:23:29 -07:00 committed by Ingo Molnar
parent 731e33e39a
commit 296f781a4b
5 changed files with 32 additions and 25 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
arch/x86/include/asm/elf.h
View File

@ -176,7 +176,7 @@ static inline void elf_common_init(struct thread_struct *t,
regs->si = regs->di = regs->bp = 0;
regs->r8 = regs->r9 = regs->r10 = regs->r11 = 0;
regs->r12 = regs->r13 = regs->r14 = regs->r15 = 0;
t->fs = t->gs = 0;
t->fsbase = t->gsbase = 0;
t->fsindex = t->gsindex = 0;
t->ds = t->es = ds;
}
@ -226,8 +226,8 @@ do { \
(pr_reg)[18] = (regs)->flags; \
(pr_reg)[19] = (regs)->sp; \
(pr_reg)[20] = (regs)->ss; \
(pr_reg)[21] = current->thread.fs; \
(pr_reg)[22] = current->thread.gs; \
(pr_reg)[21] = current->thread.fsbase; \
(pr_reg)[22] = current->thread.gsbase; \
asm("movl %%ds,%0" : "=r" (v)); (pr_reg)[23] = v; \
asm("movl %%es,%0" : "=r" (v)); (pr_reg)[24] = v; \
asm("movl %%fs,%0" : "=r" (v)); (pr_reg)[25] = v; \

11
arch/x86/include/asm/processor.h
View File

@ -388,9 +388,16 @@ struct thread_struct {
unsigned long ip;
#endif
#ifdef CONFIG_X86_64
unsigned long fs;
unsigned long fsbase;
unsigned long gsbase;
#else
/*
* XXX: this could presumably be unsigned short. Alternatively,
* 32-bit kernels could be taught to use fsindex instead.
*/
unsigned long fs;
unsigned long gs;
#endif
unsigned long gs;
/* Save middle states of ptrace breakpoints */
struct perf_event *ptrace_bps[HBP_NUM];

30
arch/x86/kernel/process_64.c
View File

@ -150,9 +150,9 @@ int copy_thread_tls(unsigned long clone_flags, unsigned long sp,
p->thread.io_bitmap_ptr = NULL;
savesegment(gs, p->thread.gsindex);
p->thread.gs = p->thread.gsindex ? 0 : me->thread.gs;
p->thread.gsbase = p->thread.gsindex ? 0 : me->thread.gsbase;
savesegment(fs, p->thread.fsindex);
p->thread.fs = p->thread.fsindex ? 0 : me->thread.fs;
p->thread.fsbase = p->thread.fsindex ? 0 : me->thread.fsbase;
savesegment(es, p->thread.es);
savesegment(ds, p->thread.ds);
memset(p->thread.ptrace_bps, 0, sizeof(p->thread.ptrace_bps));
@ -329,18 +329,18 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
* stronger guarantees.)
*
* As an invariant,
* (fs != 0 && fsindex != 0) || (gs != 0 && gsindex != 0) is
* (fsbase != 0 && fsindex != 0) || (gsbase != 0 && gsindex != 0) is
* impossible.
*/
if (next->fsindex) {
/* Loading a nonzero value into FS sets the index and base. */
loadsegment(fs, next->fsindex);
} else {
if (next->fs) {
if (next->fsbase) {
/* Next index is zero but next base is nonzero. */
if (prev_fsindex)
loadsegment(fs, 0);
wrmsrl(MSR_FS_BASE, next->fs);
wrmsrl(MSR_FS_BASE, next->fsbase);
} else {
/* Next base and index are both zero. */
if (static_cpu_has_bug(X86_BUG_NULL_SEG)) {
@ -356,7 +356,7 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
* didn't change the base, then the base is
* also zero and we don't need to do anything.
*/
if (prev->fs || prev_fsindex)
if (prev->fsbase || prev_fsindex)
loadsegment(fs, 0);
}
}
@ -369,18 +369,18 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
* us.
*/
if (prev_fsindex)
prev->fs = 0;
prev->fsbase = 0;
prev->fsindex = prev_fsindex;
if (next->gsindex) {
/* Loading a nonzero value into GS sets the index and base. */
load_gs_index(next->gsindex);
} else {
if (next->gs) {
if (next->gsbase) {
/* Next index is zero but next base is nonzero. */
if (prev_gsindex)
load_gs_index(0);
wrmsrl(MSR_KERNEL_GS_BASE, next->gs);
wrmsrl(MSR_KERNEL_GS_BASE, next->gsbase);
} else {
/* Next base and index are both zero. */
if (static_cpu_has_bug(X86_BUG_NULL_SEG)) {
@ -400,7 +400,7 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
* didn't change the base, then the base is
* also zero and we don't need to do anything.
*/
if (prev->gs || prev_gsindex)
if (prev->gsbase || prev_gsindex)
load_gs_index(0);
}
}
@ -413,7 +413,7 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
* us.
*/
if (prev_gsindex)
prev->gs = 0;
prev->gsbase = 0;
prev->gsindex = prev_gsindex;
switch_fpu_finish(next_fpu, fpu_switch);
@ -536,7 +536,7 @@ long do_arch_prctl(struct task_struct *task, int code, unsigned long addr)
return -EPERM;
cpu = get_cpu();
task->thread.gsindex = 0;
task->thread.gs = addr;
task->thread.gsbase = addr;
if (doit) {
load_gs_index(0);
ret = wrmsrl_safe(MSR_KERNEL_GS_BASE, addr);
@ -549,7 +549,7 @@ long do_arch_prctl(struct task_struct *task, int code, unsigned long addr)
return -EPERM;
cpu = get_cpu();
task->thread.fsindex = 0;
task->thread.fs = addr;
task->thread.fsbase = addr;
if (doit) {
/* set the selector to 0 to not confuse __switch_to */
loadsegment(fs, 0);
@ -562,7 +562,7 @@ long do_arch_prctl(struct task_struct *task, int code, unsigned long addr)
if (doit)
rdmsrl(MSR_FS_BASE, base);
else
base = task->thread.fs;
base = task->thread.fsbase;
ret = put_user(base, (unsigned long __user *)addr);
break;
}
@ -571,7 +571,7 @@ long do_arch_prctl(struct task_struct *task, int code, unsigned long addr)
if (doit)
rdmsrl(MSR_KERNEL_GS_BASE, base);
else
base = task->thread.gs;
base = task->thread.gsbase;
ret = put_user(base, (unsigned long __user *)addr);
break;
}

8
arch/x86/kernel/ptrace.c
View File

@ -399,7 +399,7 @@ static int putreg(struct task_struct *child,
* to set either thread.fs or thread.fsindex and the
* corresponding GDT slot.
*/
if (child->thread.fs != value)
if (child->thread.fsbase != value)
return do_arch_prctl(child, ARCH_SET_FS, value);
return 0;
case offsetof(struct user_regs_struct,gs_base):
@ -408,7 +408,7 @@ static int putreg(struct task_struct *child,
*/
if (value >= TASK_SIZE_OF(child))
return -EIO;
if (child->thread.gs != value)
if (child->thread.gsbase != value)
return do_arch_prctl(child, ARCH_SET_GS, value);
return 0;
#endif
@ -438,14 +438,14 @@ static unsigned long getreg(struct task_struct *task, unsigned long offset)
* XXX: This will not behave as expected if called on
* current or if fsindex != 0.
*/
return task->thread.fs;
return task->thread.fsbase;
}
case offsetof(struct user_regs_struct, gs_base): {
/*
* XXX: This will not behave as expected if called on
* current or if fsindex != 0.
*/
return task->thread.gs;
return task->thread.gsbase;
}
#endif
}

2
arch/x86/kvm/svm.c
View File

@ -1254,7 +1254,7 @@ static void svm_vcpu_put(struct kvm_vcpu *vcpu)
kvm_load_ldt(svm->host.ldt);
#ifdef CONFIG_X86_64
loadsegment(fs, svm->host.fs);
wrmsrl(MSR_KERNEL_GS_BASE, current->thread.gs);
wrmsrl(MSR_KERNEL_GS_BASE, current->thread.gsbase);
load_gs_index(svm->host.gs);
#else
#ifdef CONFIG_X86_32_LAZY_GS