diff options
Diffstat (limited to '')
| -rw-r--r-- | arch/i386/kernel/entry.S | 39 |
1 files changed, 26 insertions, 13 deletions
diff --git a/arch/i386/kernel/entry.S b/arch/i386/kernel/entry.S index d274612e05cd..de34b7fed3c1 100644 --- a/arch/i386/kernel/entry.S +++ b/arch/i386/kernel/entry.S @@ -53,6 +53,19 @@ #include <asm/dwarf2.h> #include "irq_vectors.h" +/* + * We use macros for low-level operations which need to be overridden + * for paravirtualization. The following will never clobber any registers: + * INTERRUPT_RETURN (aka. "iret") + * GET_CR0_INTO_EAX (aka. "movl %cr0, %eax") + * ENABLE_INTERRUPTS_SYSEXIT (aka "sti; sysexit"). + * + * For DISABLE_INTERRUPTS/ENABLE_INTERRUPTS (aka "cli"/"sti"), you must + * specify what registers can be overwritten (CLBR_NONE, CLBR_EAX/EDX/ECX/ANY). + * Allowing a register to be clobbered can shrink the paravirt replacement + * enough to patch inline, increasing performance. + */ + #define nr_syscalls ((syscall_table_size)/4) CF_MASK = 0x00000001 @@ -63,9 +76,9 @@ NT_MASK = 0x00004000 VM_MASK = 0x00020000 #ifdef CONFIG_PREEMPT -#define preempt_stop DISABLE_INTERRUPTS; TRACE_IRQS_OFF +#define preempt_stop(clobbers) DISABLE_INTERRUPTS(clobbers); TRACE_IRQS_OFF #else -#define preempt_stop +#define preempt_stop(clobbers) #define resume_kernel restore_nocheck #endif @@ -226,7 +239,7 @@ ENTRY(ret_from_fork) ALIGN RING0_PTREGS_FRAME ret_from_exception: - preempt_stop + preempt_stop(CLBR_ANY) ret_from_intr: GET_THREAD_INFO(%ebp) check_userspace: @@ -237,7 +250,7 @@ check_userspace: jb resume_kernel # not returning to v8086 or userspace ENTRY(resume_userspace) - DISABLE_INTERRUPTS # make sure we don't miss an interrupt + DISABLE_INTERRUPTS(CLBR_ANY) # make sure we don't miss an interrupt # setting need_resched or sigpending # between sampling and the iret movl TI_flags(%ebp), %ecx @@ -248,7 +261,7 @@ ENTRY(resume_userspace) #ifdef CONFIG_PREEMPT ENTRY(resume_kernel) - DISABLE_INTERRUPTS + DISABLE_INTERRUPTS(CLBR_ANY) cmpl $0,TI_preempt_count(%ebp) # non-zero preempt_count ? jnz restore_nocheck need_resched: @@ -277,7 +290,7 @@ sysenter_past_esp: * No need to follow this irqs on/off section: the syscall * disabled irqs and here we enable it straight after entry: */ - ENABLE_INTERRUPTS + ENABLE_INTERRUPTS(CLBR_NONE) pushl $(__USER_DS) CFI_ADJUST_CFA_OFFSET 4 /*CFI_REL_OFFSET ss, 0*/ @@ -322,7 +335,7 @@ sysenter_past_esp: jae syscall_badsys call *sys_call_table(,%eax,4) movl %eax,PT_EAX(%esp) - DISABLE_INTERRUPTS + DISABLE_INTERRUPTS(CLBR_ECX|CLBR_EDX) TRACE_IRQS_OFF movl TI_flags(%ebp), %ecx testw $_TIF_ALLWORK_MASK, %cx @@ -364,7 +377,7 @@ syscall_call: call *sys_call_table(,%eax,4) movl %eax,PT_EAX(%esp) # store the return value syscall_exit: - DISABLE_INTERRUPTS # make sure we don't miss an interrupt + DISABLE_INTERRUPTS(CLBR_ANY) # make sure we don't miss an interrupt # setting need_resched or sigpending # between sampling and the iret TRACE_IRQS_OFF @@ -393,7 +406,7 @@ restore_nocheck_notrace: .section .fixup,"ax" iret_exc: TRACE_IRQS_ON - ENABLE_INTERRUPTS + ENABLE_INTERRUPTS(CLBR_NONE) pushl $0 # no error code pushl $do_iret_error jmp error_code @@ -436,7 +449,7 @@ ldt_ss: CFI_ADJUST_CFA_OFFSET 4 pushl %eax CFI_ADJUST_CFA_OFFSET 4 - DISABLE_INTERRUPTS + DISABLE_INTERRUPTS(CLBR_EAX) TRACE_IRQS_OFF lss (%esp), %esp CFI_ADJUST_CFA_OFFSET -8 @@ -451,7 +464,7 @@ work_pending: jz work_notifysig work_resched: call schedule - DISABLE_INTERRUPTS # make sure we don't miss an interrupt + DISABLE_INTERRUPTS(CLBR_ANY) # make sure we don't miss an interrupt # setting need_resched or sigpending # between sampling and the iret TRACE_IRQS_OFF @@ -509,7 +522,7 @@ syscall_exit_work: testb $(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT|_TIF_SINGLESTEP), %cl jz work_pending TRACE_IRQS_ON - ENABLE_INTERRUPTS # could let do_syscall_trace() call + ENABLE_INTERRUPTS(CLBR_ANY) # could let do_syscall_trace() call # schedule() instead movl %esp, %eax movl $1, %edx @@ -693,7 +706,7 @@ ENTRY(device_not_available) GET_CR0_INTO_EAX testl $0x4, %eax # EM (math emulation bit) jne device_not_available_emulate - preempt_stop + preempt_stop(CLBR_ANY) call math_state_restore jmp ret_from_exception device_not_available_emulate: |