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-rw-r--r--arch/x86/include/asm/segment.h7
-rw-r--r--arch/x86/kernel/process_64.c71
-rw-r--r--arch/x86/kernel/ptrace.c44
3 files changed, 17 insertions, 105 deletions
diff --git a/arch/x86/include/asm/segment.h b/arch/x86/include/asm/segment.h
index e1a4afd20223..1549caa098f0 100644
--- a/arch/x86/include/asm/segment.h
+++ b/arch/x86/include/asm/segment.h
@@ -208,13 +208,6 @@
#define __USER_CS (GDT_ENTRY_DEFAULT_USER_CS*8 + 3)
#define __PER_CPU_SEG (GDT_ENTRY_PER_CPU*8 + 3)
-/* TLS indexes for 64-bit - hardcoded in arch_prctl(): */
-#define FS_TLS 0
-#define GS_TLS 1
-
-#define GS_TLS_SEL ((GDT_ENTRY_TLS_MIN+GS_TLS)*8 + 3)
-#define FS_TLS_SEL ((GDT_ENTRY_TLS_MIN+FS_TLS)*8 + 3)
-
#endif
#ifndef CONFIG_PARAVIRT
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index 24d1b7fb4399..864fe2cde3c6 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -136,25 +136,6 @@ void release_thread(struct task_struct *dead_task)
}
}
-static inline void set_32bit_tls(struct task_struct *t, int tls, u32 addr)
-{
- struct user_desc ud = {
- .base_addr = addr,
- .limit = 0xfffff,
- .seg_32bit = 1,
- .limit_in_pages = 1,
- .useable = 1,
- };
- struct desc_struct *desc = t->thread.tls_array;
- desc += tls;
- fill_ldt(desc, &ud);
-}
-
-static inline u32 read_32bit_tls(struct task_struct *t, int tls)
-{
- return get_desc_base(&t->thread.tls_array[tls]);
-}
-
int copy_thread_tls(unsigned long clone_flags, unsigned long sp,
unsigned long arg, struct task_struct *p, unsigned long tls)
{
@@ -554,25 +535,12 @@ long do_arch_prctl(struct task_struct *task, int code, unsigned long addr)
if (addr >= TASK_SIZE_OF(task))
return -EPERM;
cpu = get_cpu();
- /* handle small bases via the GDT because that's faster to
- switch. */
- if (addr <= 0xffffffff) {
- set_32bit_tls(task, GS_TLS, addr);
- if (doit) {
- load_TLS(&task->thread, cpu);
- load_gs_index(GS_TLS_SEL);
- }
- task->thread.gsindex = GS_TLS_SEL;
- task->thread.gs = 0;
- } else {
- task->thread.gsindex = 0;
- task->thread.gs = addr;
- if (doit) {
- load_gs_index(0);
- ret = wrmsrl_safe(MSR_KERNEL_GS_BASE, addr);
- }
+ task->thread.gsindex = 0;
+ task->thread.gs = addr;
+ if (doit) {
+ load_gs_index(0);
+ ret = wrmsrl_safe(MSR_KERNEL_GS_BASE, addr);
}
- put_cpu();
break;
case ARCH_SET_FS:
/* Not strictly needed for fs, but do it for symmetry
@@ -580,25 +548,12 @@ long do_arch_prctl(struct task_struct *task, int code, unsigned long addr)
if (addr >= TASK_SIZE_OF(task))
return -EPERM;
cpu = get_cpu();
- /* handle small bases via the GDT because that's faster to
- switch. */
- if (addr <= 0xffffffff) {
- set_32bit_tls(task, FS_TLS, addr);
- if (doit) {
- load_TLS(&task->thread, cpu);
- loadsegment(fs, FS_TLS_SEL);
- }
- task->thread.fsindex = FS_TLS_SEL;
- task->thread.fs = 0;
- } else {
- task->thread.fsindex = 0;
- task->thread.fs = addr;
- if (doit) {
- /* set the selector to 0 to not confuse
- __switch_to */
- loadsegment(fs, 0);
- ret = wrmsrl_safe(MSR_FS_BASE, addr);
- }
+ task->thread.fsindex = 0;
+ task->thread.fs = addr;
+ if (doit) {
+ /* set the selector to 0 to not confuse __switch_to */
+ loadsegment(fs, 0);
+ ret = wrmsrl_safe(MSR_FS_BASE, addr);
}
put_cpu();
break;
@@ -606,8 +561,6 @@ long do_arch_prctl(struct task_struct *task, int code, unsigned long addr)
unsigned long base;
if (doit)
rdmsrl(MSR_FS_BASE, base);
- else if (task->thread.fsindex == FS_TLS_SEL)
- base = read_32bit_tls(task, FS_TLS);
else
base = task->thread.fs;
ret = put_user(base, (unsigned long __user *)addr);
@@ -617,8 +570,6 @@ long do_arch_prctl(struct task_struct *task, int code, unsigned long addr)
unsigned long base;
if (doit)
rdmsrl(MSR_KERNEL_GS_BASE, base);
- else if (task->thread.gsindex == GS_TLS_SEL)
- base = read_32bit_tls(task, GS_TLS);
else
base = task->thread.gs;
ret = put_user(base, (unsigned long __user *)addr);
diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
index 0f4d2a5df2dc..e72ab40fa969 100644
--- a/arch/x86/kernel/ptrace.c
+++ b/arch/x86/kernel/ptrace.c
@@ -303,29 +303,11 @@ static int set_segment_reg(struct task_struct *task,
switch (offset) {
case offsetof(struct user_regs_struct,fs):
- /*
- * If this is setting fs as for normal 64-bit use but
- * setting fs_base has implicitly changed it, leave it.
- */
- if ((value == FS_TLS_SEL && task->thread.fsindex == 0 &&
- task->thread.fs != 0) ||
- (value == 0 && task->thread.fsindex == FS_TLS_SEL &&
- task->thread.fs == 0))
- break;
task->thread.fsindex = value;
if (task == current)
loadsegment(fs, task->thread.fsindex);
break;
case offsetof(struct user_regs_struct,gs):
- /*
- * If this is setting gs as for normal 64-bit use but
- * setting gs_base has implicitly changed it, leave it.
- */
- if ((value == GS_TLS_SEL && task->thread.gsindex == 0 &&
- task->thread.gs != 0) ||
- (value == 0 && task->thread.gsindex == GS_TLS_SEL &&
- task->thread.gs == 0))
- break;
task->thread.gsindex = value;
if (task == current)
load_gs_index(task->thread.gsindex);
@@ -453,31 +435,17 @@ static unsigned long getreg(struct task_struct *task, unsigned long offset)
#ifdef CONFIG_X86_64
case offsetof(struct user_regs_struct, fs_base): {
/*
- * do_arch_prctl may have used a GDT slot instead of
- * the MSR. To userland, it appears the same either
- * way, except the %fs segment selector might not be 0.
+ * XXX: This will not behave as expected if called on
+ * current or if fsindex != 0.
*/
- unsigned int seg = task->thread.fsindex;
- if (task->thread.fs != 0)
- return task->thread.fs;
- if (task == current)
- asm("movl %%fs,%0" : "=r" (seg));
- if (seg != FS_TLS_SEL)
- return 0;
- return get_desc_base(&task->thread.tls_array[FS_TLS]);
+ return task->thread.fs;
}
case offsetof(struct user_regs_struct, gs_base): {
/*
- * Exactly the same here as the %fs handling above.
+ * XXX: This will not behave as expected if called on
+ * current or if fsindex != 0.
*/
- unsigned int seg = task->thread.gsindex;
- if (task->thread.gs != 0)
- return task->thread.gs;
- if (task == current)
- asm("movl %%gs,%0" : "=r" (seg));
- if (seg != GS_TLS_SEL)
- return 0;
- return get_desc_base(&task->thread.tls_array[GS_TLS]);
+ return task->thread.gs;
}
#endif
}
generated by cgit (git 2.34.1) at 2024-06-19 12:57:53 +0000