# define preempt_stop(clobbers) DISABLE_INTERRUPTS(clobbers); TRACE_IRQS_OFF
#else
# define preempt_stop(clobbers)
-# define resume_kernel restore_all_kernel
#endif
.macro TRACE_IRQS_IRET
.Lend_\@:
.endm
+#define CS_FROM_ENTRY_STACK (1 << 31)
+#define CS_FROM_USER_CR3 (1 << 30)
+#define CS_FROM_KERNEL (1 << 29)
+
+.macro FIXUP_FRAME
+ /*
+ * The high bits of the CS dword (__csh) are used for CS_FROM_*.
+ * Clear them in case hardware didn't do this for us.
+ */
+ andl $0x0000ffff, 3*4(%esp)
+
+#ifdef CONFIG_VM86
+ testl $X86_EFLAGS_VM, 4*4(%esp)
+ jnz .Lfrom_usermode_no_fixup_\@
+#endif
+ testl $SEGMENT_RPL_MASK, 3*4(%esp)
+ jnz .Lfrom_usermode_no_fixup_\@
+
+ orl $CS_FROM_KERNEL, 3*4(%esp)
+
+ /*
+ * When we're here from kernel mode; the (exception) stack looks like:
+ *
+ * 5*4(%esp) - <previous context>
+ * 4*4(%esp) - flags
+ * 3*4(%esp) - cs
+ * 2*4(%esp) - ip
+ * 1*4(%esp) - orig_eax
+ * 0*4(%esp) - gs / function
+ *
+ * Lets build a 5 entry IRET frame after that, such that struct pt_regs
+ * is complete and in particular regs->sp is correct. This gives us
+ * the original 5 enties as gap:
+ *
+ * 12*4(%esp) - <previous context>
+ * 11*4(%esp) - gap / flags
+ * 10*4(%esp) - gap / cs
+ * 9*4(%esp) - gap / ip
+ * 8*4(%esp) - gap / orig_eax
+ * 7*4(%esp) - gap / gs / function
+ * 6*4(%esp) - ss
+ * 5*4(%esp) - sp
+ * 4*4(%esp) - flags
+ * 3*4(%esp) - cs
+ * 2*4(%esp) - ip
+ * 1*4(%esp) - orig_eax
+ * 0*4(%esp) - gs / function
+ */
+
+ pushl %ss # ss
+ pushl %esp # sp (points at ss)
+ addl $6*4, (%esp) # point sp back at the previous context
+ pushl 6*4(%esp) # flags
+ pushl 6*4(%esp) # cs
+ pushl 6*4(%esp) # ip
+ pushl 6*4(%esp) # orig_eax
+ pushl 6*4(%esp) # gs / function
+.Lfrom_usermode_no_fixup_\@:
+.endm
+
+.macro IRET_FRAME
+ testl $CS_FROM_KERNEL, 1*4(%esp)
+ jz .Lfinished_frame_\@
+
+ /*
+ * Reconstruct the 3 entry IRET frame right after the (modified)
+ * regs->sp without lowering %esp in between, such that an NMI in the
+ * middle doesn't scribble our stack.
+ */
+ pushl %eax
+ pushl %ecx
+ movl 5*4(%esp), %eax # (modified) regs->sp
+
+ movl 4*4(%esp), %ecx # flags
+ movl %ecx, -4(%eax)
+
+ movl 3*4(%esp), %ecx # cs
+ andl $0x0000ffff, %ecx
+ movl %ecx, -8(%eax)
+
+ movl 2*4(%esp), %ecx # ip
+ movl %ecx, -12(%eax)
+
+ movl 1*4(%esp), %ecx # eax
+ movl %ecx, -16(%eax)
+
+ popl %ecx
+ lea -16(%eax), %esp
+ popl %eax
+.Lfinished_frame_\@:
+.endm
+
.macro SAVE_ALL pt_regs_ax=%eax switch_stacks=0
cld
PUSH_GS
+ FIXUP_FRAME
pushl %fs
pushl %es
pushl %ds
.Lend_\@:
.endm
-/*
- * This is a sneaky trick to help the unwinder find pt_regs on the stack. The
- * frame pointer is replaced with an encoded pointer to pt_regs. The encoding
- * is just clearing the MSB, which makes it an invalid stack address and is also
- * a signal to the unwinder that it's a pt_regs pointer in disguise.
- *
- * NOTE: This macro must be used *after* SAVE_ALL because it corrupts the
- * original rbp.
- */
-.macro ENCODE_FRAME_POINTER
-#ifdef CONFIG_FRAME_POINTER
- mov %esp, %ebp
- andl $0x7fffffff, %ebp
-#endif
-.endm
-
.macro RESTORE_INT_REGS
popl %ebx
popl %ecx
* switch to it before we do any copying.
*/
-#define CS_FROM_ENTRY_STACK (1 << 31)
-#define CS_FROM_USER_CR3 (1 << 30)
-
.macro SWITCH_TO_KERNEL_STACK
ALTERNATIVE "", "jmp .Lend_\@", X86_FEATURE_XENPV
* that register for the time this macro runs
*/
- /*
- * The high bits of the CS dword (__csh) are used for
- * CS_FROM_ENTRY_STACK and CS_FROM_USER_CR3. Clear them in case
- * hardware didn't do this for us.
- */
- andl $(0x0000ffff), PT_CS(%esp)
-
/* Are we on the entry stack? Bail out if not! */
movl PER_CPU_VAR(cpu_entry_area), %ecx
addl $CPU_ENTRY_AREA_entry_stack + SIZEOF_entry_stack, %ecx
andl $SEGMENT_RPL_MASK, %eax
#endif
cmpl $USER_RPL, %eax
- jb resume_kernel # not returning to v8086 or userspace
+ jb restore_all_kernel # not returning to v8086 or userspace
ENTRY(resume_userspace)
DISABLE_INTERRUPTS(CLBR_ANY)
jmp restore_all
END(ret_from_exception)
-#ifdef CONFIG_PREEMPT
-ENTRY(resume_kernel)
- DISABLE_INTERRUPTS(CLBR_ANY)
- cmpl $0, PER_CPU_VAR(__preempt_count)
- jnz restore_all_kernel
- testl $X86_EFLAGS_IF, PT_EFLAGS(%esp) # interrupts off (exception path) ?
- jz restore_all_kernel
- call preempt_schedule_irq
- jmp restore_all_kernel
-END(resume_kernel)
-#endif
-
GLOBAL(__begin_SYSENTER_singlestep_region)
/*
* All code from here through __end_SYSENTER_singlestep_region is subject
/* Restore user state */
RESTORE_REGS pop=4 # skip orig_eax/error_code
.Lirq_return:
+ IRET_FRAME
/*
* ARCH_HAS_MEMBARRIER_SYNC_CORE rely on IRET core serialization
* when returning from IPI handler and when returning from
INTERRUPT_RETURN
restore_all_kernel:
+#ifdef CONFIG_PREEMPT
+ DISABLE_INTERRUPTS(CLBR_ANY)
+ cmpl $0, PER_CPU_VAR(__preempt_count)
+ jnz .Lno_preempt
+ testl $X86_EFLAGS_IF, PT_EFLAGS(%esp) # interrupts off (exception path) ?
+ jz .Lno_preempt
+ call preempt_schedule_irq
+.Lno_preempt:
+#endif
TRACE_IRQS_IRET
PARANOID_EXIT_TO_KERNEL_MODE
BUG_IF_WRONG_CR3
common_exception:
/* the function address is in %gs's slot on the stack */
+ FIXUP_FRAME
pushl %fs
pushl %es
pushl %ds
projects / linux-2.6-block.git / blobdiff