diff options
Diffstat (limited to 'arch/i386/kernel/entry.S')
| -rw-r--r-- | arch/i386/kernel/entry.S | 329 |
1 files changed, 167 insertions, 162 deletions
diff --git a/arch/i386/kernel/entry.S b/arch/i386/kernel/entry.S index 5a63d6fdb70e..06461b8b715d 100644 --- a/arch/i386/kernel/entry.S +++ b/arch/i386/kernel/entry.S @@ -30,12 +30,13 @@ * 18(%esp) - %eax * 1C(%esp) - %ds * 20(%esp) - %es - * 24(%esp) - orig_eax - * 28(%esp) - %eip - * 2C(%esp) - %cs - * 30(%esp) - %eflags - * 34(%esp) - %oldesp - * 38(%esp) - %oldss + * 24(%esp) - %gs + * 28(%esp) - orig_eax + * 2C(%esp) - %eip + * 30(%esp) - %cs + * 34(%esp) - %eflags + * 38(%esp) - %oldesp + * 3C(%esp) - %oldss * * "current" is in register %ebx during any slow entries. */ @@ -48,26 +49,24 @@ #include <asm/smp.h> #include <asm/page.h> #include <asm/desc.h> +#include <asm/percpu.h> #include <asm/dwarf2.h> #include "irq_vectors.h" -#define nr_syscalls ((syscall_table_size)/4) +/* + * 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. + */ -EBX = 0x00 -ECX = 0x04 -EDX = 0x08 -ESI = 0x0C -EDI = 0x10 -EBP = 0x14 -EAX = 0x18 -DS = 0x1C -ES = 0x20 -ORIG_EAX = 0x24 -EIP = 0x28 -CS = 0x2C -EFLAGS = 0x30 -OLDESP = 0x34 -OLDSS = 0x38 +#define nr_syscalls ((syscall_table_size)/4) CF_MASK = 0x00000001 TF_MASK = 0x00000100 @@ -76,23 +75,16 @@ DF_MASK = 0x00000400 NT_MASK = 0x00004000 VM_MASK = 0x00020000 -/* These are replaces for paravirtualization */ -#define DISABLE_INTERRUPTS cli -#define ENABLE_INTERRUPTS sti -#define ENABLE_INTERRUPTS_SYSEXIT sti; sysexit -#define INTERRUPT_RETURN iret -#define GET_CR0_INTO_EAX movl %cr0, %eax - #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 .macro TRACE_IRQS_IRET #ifdef CONFIG_TRACE_IRQFLAGS - testl $IF_MASK,EFLAGS(%esp) # interrupts off? + testl $IF_MASK,PT_EFLAGS(%esp) # interrupts off? jz 1f TRACE_IRQS_ON 1: @@ -107,6 +99,9 @@ VM_MASK = 0x00020000 #define SAVE_ALL \ cld; \ + pushl %gs; \ + CFI_ADJUST_CFA_OFFSET 4;\ + /*CFI_REL_OFFSET gs, 0;*/\ pushl %es; \ CFI_ADJUST_CFA_OFFSET 4;\ /*CFI_REL_OFFSET es, 0;*/\ @@ -136,7 +131,9 @@ VM_MASK = 0x00020000 CFI_REL_OFFSET ebx, 0;\ movl $(__USER_DS), %edx; \ movl %edx, %ds; \ - movl %edx, %es; + movl %edx, %es; \ + movl $(__KERNEL_PDA), %edx; \ + movl %edx, %gs #define RESTORE_INT_REGS \ popl %ebx; \ @@ -169,17 +166,22 @@ VM_MASK = 0x00020000 2: popl %es; \ CFI_ADJUST_CFA_OFFSET -4;\ /*CFI_RESTORE es;*/\ -.section .fixup,"ax"; \ -3: movl $0,(%esp); \ - jmp 1b; \ +3: popl %gs; \ + CFI_ADJUST_CFA_OFFSET -4;\ + /*CFI_RESTORE gs;*/\ +.pushsection .fixup,"ax"; \ 4: movl $0,(%esp); \ + jmp 1b; \ +5: movl $0,(%esp); \ jmp 2b; \ -.previous; \ +6: movl $0,(%esp); \ + jmp 3b; \ .section __ex_table,"a";\ .align 4; \ - .long 1b,3b; \ - .long 2b,4b; \ -.previous + .long 1b,4b; \ + .long 2b,5b; \ + .long 3b,6b; \ +.popsection #define RING0_INT_FRAME \ CFI_STARTPROC simple;\ @@ -198,18 +200,18 @@ VM_MASK = 0x00020000 #define RING0_PTREGS_FRAME \ CFI_STARTPROC simple;\ CFI_SIGNAL_FRAME;\ - CFI_DEF_CFA esp, OLDESP-EBX;\ - /*CFI_OFFSET cs, CS-OLDESP;*/\ - CFI_OFFSET eip, EIP-OLDESP;\ - /*CFI_OFFSET es, ES-OLDESP;*/\ - /*CFI_OFFSET ds, DS-OLDESP;*/\ - CFI_OFFSET eax, EAX-OLDESP;\ - CFI_OFFSET ebp, EBP-OLDESP;\ - CFI_OFFSET edi, EDI-OLDESP;\ - CFI_OFFSET esi, ESI-OLDESP;\ - CFI_OFFSET edx, EDX-OLDESP;\ - CFI_OFFSET ecx, ECX-OLDESP;\ - CFI_OFFSET ebx, EBX-OLDESP + CFI_DEF_CFA esp, PT_OLDESP-PT_EBX;\ + /*CFI_OFFSET cs, PT_CS-PT_OLDESP;*/\ + CFI_OFFSET eip, PT_EIP-PT_OLDESP;\ + /*CFI_OFFSET es, PT_ES-PT_OLDESP;*/\ + /*CFI_OFFSET ds, PT_DS-PT_OLDESP;*/\ + CFI_OFFSET eax, PT_EAX-PT_OLDESP;\ + CFI_OFFSET ebp, PT_EBP-PT_OLDESP;\ + CFI_OFFSET edi, PT_EDI-PT_OLDESP;\ + CFI_OFFSET esi, PT_ESI-PT_OLDESP;\ + CFI_OFFSET edx, PT_EDX-PT_OLDESP;\ + CFI_OFFSET ecx, PT_ECX-PT_OLDESP;\ + CFI_OFFSET ebx, PT_EBX-PT_OLDESP ENTRY(ret_from_fork) CFI_STARTPROC @@ -237,17 +239,18 @@ 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: - movl EFLAGS(%esp), %eax # mix EFLAGS and CS - movb CS(%esp), %al + movl PT_EFLAGS(%esp), %eax # mix EFLAGS and CS + movb PT_CS(%esp), %al andl $(VM_MASK | SEGMENT_RPL_MASK), %eax cmpl $USER_RPL, %eax 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 @@ -258,14 +261,14 @@ 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: movl TI_flags(%ebp), %ecx # need_resched set ? testb $_TIF_NEED_RESCHED, %cl jz restore_all - testl $IF_MASK,EFLAGS(%esp) # interrupts off (exception path) ? + testl $IF_MASK,PT_EFLAGS(%esp) # interrupts off (exception path) ? jz restore_all call preempt_schedule_irq jmp need_resched @@ -287,7 +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*/ @@ -331,20 +334,27 @@ sysenter_past_esp: cmpl $(nr_syscalls), %eax jae syscall_badsys call *sys_call_table(,%eax,4) - movl %eax,EAX(%esp) - DISABLE_INTERRUPTS + movl %eax,PT_EAX(%esp) + DISABLE_INTERRUPTS(CLBR_ECX|CLBR_EDX) TRACE_IRQS_OFF movl TI_flags(%ebp), %ecx testw $_TIF_ALLWORK_MASK, %cx jne syscall_exit_work /* if something modifies registers it must also disable sysexit */ - movl EIP(%esp), %edx - movl OLDESP(%esp), %ecx + movl PT_EIP(%esp), %edx + movl PT_OLDESP(%esp), %ecx xorl %ebp,%ebp TRACE_IRQS_ON +1: mov PT_GS(%esp), %gs ENABLE_INTERRUPTS_SYSEXIT CFI_ENDPROC - +.pushsection .fixup,"ax" +2: movl $0,PT_GS(%esp) + jmp 1b +.section __ex_table,"a" + .align 4 + .long 1b,2b +.popsection # system call handler stub ENTRY(system_call) @@ -353,7 +363,7 @@ ENTRY(system_call) CFI_ADJUST_CFA_OFFSET 4 SAVE_ALL GET_THREAD_INFO(%ebp) - testl $TF_MASK,EFLAGS(%esp) + testl $TF_MASK,PT_EFLAGS(%esp) jz no_singlestep orl $_TIF_SINGLESTEP,TI_flags(%ebp) no_singlestep: @@ -365,9 +375,9 @@ no_singlestep: jae syscall_badsys syscall_call: call *sys_call_table(,%eax,4) - movl %eax,EAX(%esp) # store the return value + 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 @@ -376,12 +386,12 @@ syscall_exit: jne syscall_exit_work restore_all: - movl EFLAGS(%esp), %eax # mix EFLAGS, SS and CS - # Warning: OLDSS(%esp) contains the wrong/random values if we + movl PT_EFLAGS(%esp), %eax # mix EFLAGS, SS and CS + # Warning: PT_OLDSS(%esp) contains the wrong/random values if we # are returning to the kernel. # See comments in process.c:copy_thread() for details. - movb OLDSS(%esp), %ah - movb CS(%esp), %al + movb PT_OLDSS(%esp), %ah + movb PT_CS(%esp), %al andl $(VM_MASK | (SEGMENT_TI_MASK << 8) | SEGMENT_RPL_MASK), %eax cmpl $((SEGMENT_LDT << 8) | USER_RPL), %eax CFI_REMEMBER_STATE @@ -390,13 +400,13 @@ restore_nocheck: TRACE_IRQS_IRET restore_nocheck_notrace: RESTORE_REGS - addl $4, %esp + addl $4, %esp # skip orig_eax/error_code CFI_ADJUST_CFA_OFFSET -4 1: INTERRUPT_RETURN .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 @@ -408,33 +418,42 @@ iret_exc: CFI_RESTORE_STATE ldt_ss: - larl OLDSS(%esp), %eax + larl PT_OLDSS(%esp), %eax jnz restore_nocheck testl $0x00400000, %eax # returning to 32bit stack? jnz restore_nocheck # allright, normal return + +#ifdef CONFIG_PARAVIRT + /* + * The kernel can't run on a non-flat stack if paravirt mode + * is active. Rather than try to fixup the high bits of + * ESP, bypass this code entirely. This may break DOSemu + * and/or Wine support in a paravirt VM, although the option + * is still available to implement the setting of the high + * 16-bits in the INTERRUPT_RETURN paravirt-op. + */ + cmpl $0, paravirt_ops+PARAVIRT_enabled + jne restore_nocheck +#endif + /* If returning to userspace with 16bit stack, * try to fix the higher word of ESP, as the CPU * won't restore it. * This is an "official" bug of all the x86-compatible * CPUs, which we can try to work around to make * dosemu and wine happy. */ - subl $8, %esp # reserve space for switch16 pointer - CFI_ADJUST_CFA_OFFSET 8 - DISABLE_INTERRUPTS + movl PT_OLDESP(%esp), %eax + movl %esp, %edx + call patch_espfix_desc + pushl $__ESPFIX_SS + CFI_ADJUST_CFA_OFFSET 4 + pushl %eax + CFI_ADJUST_CFA_OFFSET 4 + DISABLE_INTERRUPTS(CLBR_EAX) TRACE_IRQS_OFF - movl %esp, %eax - /* Set up the 16bit stack frame with switch32 pointer on top, - * and a switch16 pointer on top of the current frame. */ - call setup_x86_bogus_stack - CFI_ADJUST_CFA_OFFSET -8 # frame has moved - TRACE_IRQS_IRET - RESTORE_REGS - lss 20+4(%esp), %esp # switch to 16bit stack -1: INTERRUPT_RETURN -.section __ex_table,"a" - .align 4 - .long 1b,iret_exc -.previous + lss (%esp), %esp + CFI_ADJUST_CFA_OFFSET -8 + jmp restore_nocheck CFI_ENDPROC # perform work that needs to be done immediately before resumption @@ -445,7 +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 @@ -458,7 +477,8 @@ work_resched: work_notifysig: # deal with pending signals and # notify-resume requests - testl $VM_MASK, EFLAGS(%esp) +#ifdef CONFIG_VM86 + testl $VM_MASK, PT_EFLAGS(%esp) movl %esp, %eax jne work_notifysig_v86 # returning to kernel-space or # vm86-space @@ -468,29 +488,30 @@ work_notifysig: # deal with pending signals and ALIGN work_notifysig_v86: -#ifdef CONFIG_VM86 pushl %ecx # save ti_flags for do_notify_resume CFI_ADJUST_CFA_OFFSET 4 call save_v86_state # %eax contains pt_regs pointer popl %ecx CFI_ADJUST_CFA_OFFSET -4 movl %eax, %esp +#else + movl %esp, %eax +#endif xorl %edx, %edx call do_notify_resume jmp resume_userspace_sig -#endif # perform syscall exit tracing ALIGN syscall_trace_entry: - movl $-ENOSYS,EAX(%esp) + movl $-ENOSYS,PT_EAX(%esp) movl %esp, %eax xorl %edx,%edx call do_syscall_trace cmpl $0, %eax jne resume_userspace # ret != 0 -> running under PTRACE_SYSEMU, # so must skip actual syscall - movl ORIG_EAX(%esp), %eax + movl PT_ORIG_EAX(%esp), %eax cmpl $(nr_syscalls), %eax jnae syscall_call jmp syscall_exit @@ -501,7 +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 @@ -515,39 +536,38 @@ syscall_fault: CFI_ADJUST_CFA_OFFSET 4 SAVE_ALL GET_THREAD_INFO(%ebp) - movl $-EFAULT,EAX(%esp) + movl $-EFAULT,PT_EAX(%esp) jmp resume_userspace syscall_badsys: - movl $-ENOSYS,EAX(%esp) + movl $-ENOSYS,PT_EAX(%esp) jmp resume_userspace CFI_ENDPROC #define FIXUP_ESPFIX_STACK \ - movl %esp, %eax; \ - /* switch to 32bit stack using the pointer on top of 16bit stack */ \ - lss %ss:CPU_16BIT_STACK_SIZE-8, %esp; \ - /* copy data from 16bit stack to 32bit stack */ \ - call fixup_x86_bogus_stack; \ - /* put ESP to the proper location */ \ - movl %eax, %esp; -#define UNWIND_ESPFIX_STACK \ + /* since we are on a wrong stack, we cant make it a C code :( */ \ + movl %gs:PDA_cpu, %ebx; \ + PER_CPU(cpu_gdt_descr, %ebx); \ + movl GDS_address(%ebx), %ebx; \ + GET_DESC_BASE(GDT_ENTRY_ESPFIX_SS, %ebx, %eax, %ax, %al, %ah); \ + addl %esp, %eax; \ + pushl $__KERNEL_DS; \ + CFI_ADJUST_CFA_OFFSET 4; \ pushl %eax; \ CFI_ADJUST_CFA_OFFSET 4; \ + lss (%esp), %esp; \ + CFI_ADJUST_CFA_OFFSET -8; +#define UNWIND_ESPFIX_STACK \ movl %ss, %eax; \ - /* see if on 16bit stack */ \ + /* see if on espfix stack */ \ cmpw $__ESPFIX_SS, %ax; \ - je 28f; \ -27: popl %eax; \ - CFI_ADJUST_CFA_OFFSET -4; \ -.section .fixup,"ax"; \ -28: movl $__KERNEL_DS, %eax; \ + jne 27f; \ + movl $__KERNEL_DS, %eax; \ movl %eax, %ds; \ movl %eax, %es; \ - /* switch to 32bit stack */ \ + /* switch to normal stack */ \ FIXUP_ESPFIX_STACK; \ - jmp 27b; \ -.previous +27:; /* * Build the entry stubs and pointer table with @@ -608,13 +628,16 @@ KPROBE_ENTRY(page_fault) CFI_ADJUST_CFA_OFFSET 4 ALIGN error_code: + /* the function address is in %gs's slot on the stack */ + pushl %es + CFI_ADJUST_CFA_OFFSET 4 + /*CFI_REL_OFFSET es, 0*/ pushl %ds CFI_ADJUST_CFA_OFFSET 4 /*CFI_REL_OFFSET ds, 0*/ pushl %eax CFI_ADJUST_CFA_OFFSET 4 CFI_REL_OFFSET eax, 0 - xorl %eax, %eax pushl %ebp CFI_ADJUST_CFA_OFFSET 4 CFI_REL_OFFSET ebp, 0 @@ -627,7 +650,6 @@ error_code: pushl %edx CFI_ADJUST_CFA_OFFSET 4 CFI_REL_OFFSET edx, 0 - decl %eax # eax = -1 pushl %ecx CFI_ADJUST_CFA_OFFSET 4 CFI_REL_OFFSET ecx, 0 @@ -635,18 +657,20 @@ error_code: CFI_ADJUST_CFA_OFFSET 4 CFI_REL_OFFSET ebx, 0 cld - pushl %es + pushl %gs CFI_ADJUST_CFA_OFFSET 4 - /*CFI_REL_OFFSET es, 0*/ + /*CFI_REL_OFFSET gs, 0*/ + movl $(__KERNEL_PDA), %ecx + movl %ecx, %gs UNWIND_ESPFIX_STACK popl %ecx CFI_ADJUST_CFA_OFFSET -4 /*CFI_REGISTER es, ecx*/ - movl ES(%esp), %edi # get the function address - movl ORIG_EAX(%esp), %edx # get the error code - movl %eax, ORIG_EAX(%esp) - movl %ecx, ES(%esp) - /*CFI_REL_OFFSET es, ES*/ + movl PT_GS(%esp), %edi # get the function address + movl PT_ORIG_EAX(%esp), %edx # get the error code + movl $-1, PT_ORIG_EAX(%esp) # no syscall to restart + mov %ecx, PT_GS(%esp) + /*CFI_REL_OFFSET gs, ES*/ movl $(__USER_DS), %ecx movl %ecx, %ds movl %ecx, %es @@ -682,7 +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: @@ -754,7 +778,7 @@ KPROBE_ENTRY(nmi) cmpw $__ESPFIX_SS, %ax popl %eax CFI_ADJUST_CFA_OFFSET -4 - je nmi_16bit_stack + je nmi_espfix_stack cmpl $sysenter_entry,(%esp) je nmi_stack_fixup pushl %eax @@ -797,7 +821,7 @@ nmi_debug_stack_check: FIX_STACK(24,nmi_stack_correct, 1) jmp nmi_stack_correct -nmi_16bit_stack: +nmi_espfix_stack: /* We have a RING0_INT_FRAME here. * * create the pointer to lss back @@ -806,7 +830,6 @@ nmi_16bit_stack: CFI_ADJUST_CFA_OFFSET 4 pushl %esp CFI_ADJUST_CFA_OFFSET 4 - movzwl %sp, %esp addw $4, (%esp) /* copy the iret frame of 12 bytes */ .rept 3 @@ -817,11 +840,11 @@ nmi_16bit_stack: CFI_ADJUST_CFA_OFFSET 4 SAVE_ALL FIXUP_ESPFIX_STACK # %eax == %esp - CFI_ADJUST_CFA_OFFSET -20 # the frame has now moved xorl %edx,%edx # zero error code call do_nmi RESTORE_REGS - lss 12+4(%esp), %esp # back to 16bit stack + lss 12+4(%esp), %esp # back to espfix stack + CFI_ADJUST_CFA_OFFSET -24 1: INTERRUPT_RETURN CFI_ENDPROC .section __ex_table,"a" @@ -830,6 +853,19 @@ nmi_16bit_stack: .previous KPROBE_END(nmi) +#ifdef CONFIG_PARAVIRT +ENTRY(native_iret) +1: iret +.section __ex_table,"a" + .align 4 + .long 1b,iret_exc +.previous + +ENTRY(native_irq_enable_sysexit) + sti + sysexit +#endif + KPROBE_ENTRY(int3) RING0_INT_FRAME pushl $-1 # mark this as an int @@ -943,37 +979,6 @@ ENTRY(spurious_interrupt_bug) jmp error_code CFI_ENDPROC -#ifdef CONFIG_STACK_UNWIND -ENTRY(arch_unwind_init_running) - CFI_STARTPROC - movl 4(%esp), %edx - movl (%esp), %ecx - leal 4(%esp), %eax - movl %ebx, EBX(%edx) - xorl %ebx, %ebx - movl %ebx, ECX(%edx) - movl %ebx, EDX(%edx) - movl %esi, ESI(%edx) - movl %edi, EDI(%edx) - movl %ebp, EBP(%edx) - movl %ebx, EAX(%edx) - movl $__USER_DS, DS(%edx) - movl $__USER_DS, ES(%edx) - movl %ebx, ORIG_EAX(%edx) - movl %ecx, EIP(%edx) - movl 12(%esp), %ecx - movl $__KERNEL_CS, CS(%edx) - movl %ebx, EFLAGS(%edx) - movl %eax, OLDESP(%edx) - movl 8(%esp), %eax - movl %ecx, 8(%esp) - movl EBX(%edx), %ebx - movl $__KERNEL_DS, OLDSS(%edx) - jmpl *%eax - CFI_ENDPROC -ENDPROC(arch_unwind_init_running) -#endif - ENTRY(kernel_thread_helper) pushl $0 # fake return address for unwinder CFI_STARTPROC |