x86: move switch_to macro to system.h
This patch moves the switch_to() macro to system.h
As those macros are fundamentally different between i386 and x86_64,
they are enclosed around an ifdef.
Signed-off-by: Glauber de Oliveira Costa <gcosta@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/include/asm-x86/system.h b/include/asm-x86/system.h
index 4c15eb1..ba3403f 100644
--- a/include/asm-x86/system.h
+++ b/include/asm-x86/system.h
@@ -6,8 +6,69 @@
#include <linux/kernel.h>
#ifdef CONFIG_X86_32
+#define AT_VECTOR_SIZE_ARCH 2 /* entries in ARCH_DLINFO */
+
+struct task_struct; /* one of the stranger aspects of C forward declarations */
+extern struct task_struct *FASTCALL(__switch_to(struct task_struct *prev,
+ struct task_struct *next));
+
+/*
+ * Saving eflags is important. It switches not only IOPL between tasks,
+ * it also protects other tasks from NT leaking through sysenter etc.
+ */
+#define switch_to(prev, next, last) do { \
+ unsigned long esi, edi; \
+ asm volatile("pushfl\n\t" /* Save flags */ \
+ "pushl %%ebp\n\t" \
+ "movl %%esp,%0\n\t" /* save ESP */ \
+ "movl %5,%%esp\n\t" /* restore ESP */ \
+ "movl $1f,%1\n\t" /* save EIP */ \
+ "pushl %6\n\t" /* restore EIP */ \
+ "jmp __switch_to\n" \
+ "1:\t" \
+ "popl %%ebp\n\t" \
+ "popfl" \
+ :"=m" (prev->thread.sp), "=m" (prev->thread.ip), \
+ "=a" (last), "=S" (esi), "=D" (edi) \
+ :"m" (next->thread.sp), "m" (next->thread.ip), \
+ "2" (prev), "d" (next)); \
+} while (0)
+
# include "system_32.h"
#else
+#define __SAVE(reg, offset) "movq %%" #reg ",(14-" #offset ")*8(%%rsp)\n\t"
+#define __RESTORE(reg, offset) "movq (14-" #offset ")*8(%%rsp),%%" #reg "\n\t"
+
+/* frame pointer must be last for get_wchan */
+#define SAVE_CONTEXT "pushf ; pushq %%rbp ; movq %%rsi,%%rbp\n\t"
+#define RESTORE_CONTEXT "movq %%rbp,%%rsi ; popq %%rbp ; popf\t"
+
+#define __EXTRA_CLOBBER \
+ , "rcx", "rbx", "rdx", "r8", "r9", "r10", "r11", \
+ "r12", "r13", "r14", "r15"
+
+/* Save restore flags to clear handle leaking NT */
+#define switch_to(prev, next, last) \
+ asm volatile(SAVE_CONTEXT \
+ "movq %%rsp,%P[threadrsp](%[prev])\n\t" /* save RSP */ \
+ "movq %P[threadrsp](%[next]),%%rsp\n\t" /* restore RSP */ \
+ "call __switch_to\n\t" \
+ ".globl thread_return\n" \
+ "thread_return:\n\t" \
+ "movq %%gs:%P[pda_pcurrent],%%rsi\n\t" \
+ "movq %P[thread_info](%%rsi),%%r8\n\t" \
+ LOCK_PREFIX "btr %[tif_fork],%P[ti_flags](%%r8)\n\t" \
+ "movq %%rax,%%rdi\n\t" \
+ "jc ret_from_fork\n\t" \
+ RESTORE_CONTEXT \
+ : "=a" (last) \
+ : [next] "S" (next), [prev] "D" (prev), \
+ [threadrsp] "i" (offsetof(struct task_struct, thread.sp)), \
+ [ti_flags] "i" (offsetof(struct thread_info, flags)), \
+ [tif_fork] "i" (TIF_FORK), \
+ [thread_info] "i" (offsetof(struct task_struct, stack)), \
+ [pda_pcurrent] "i" (offsetof(struct x8664_pda, pcurrent)) \
+ : "memory", "cc" __EXTRA_CLOBBER)
# include "system_64.h"
#endif