Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
diff --git a/arch/x86_64/kernel/entry.S b/arch/x86_64/kernel/entry.S
new file mode 100644
index 0000000..e126284
--- /dev/null
+++ b/arch/x86_64/kernel/entry.S
@@ -0,0 +1,920 @@
+/*
+ * linux/arch/x86_64/entry.S
+ *
+ * Copyright (C) 1991, 1992 Linus Torvalds
+ * Copyright (C) 2000, 2001, 2002 Andi Kleen SuSE Labs
+ * Copyright (C) 2000 Pavel Machek <pavel@suse.cz>
+ *
+ * $Id$
+ */
+
+/*
+ * entry.S contains the system-call and fault low-level handling routines.
+ *
+ * NOTE: This code handles signal-recognition, which happens every time
+ * after an interrupt and after each system call.
+ *
+ * Normal syscalls and interrupts don't save a full stack frame, this is
+ * only done for syscall tracing, signals or fork/exec et.al.
+ *
+ * A note on terminology:
+ * - top of stack: Architecture defined interrupt frame from SS to RIP
+ * at the top of the kernel process stack.
+ * - partial stack frame: partially saved registers upto R11.
+ * - full stack frame: Like partial stack frame, but all register saved.
+ *
+ * TODO:
+ * - schedule it carefully for the final hardware.
+ */
+
+#define ASSEMBLY 1
+#include <linux/config.h>
+#include <linux/linkage.h>
+#include <asm/segment.h>
+#include <asm/smp.h>
+#include <asm/cache.h>
+#include <asm/errno.h>
+#include <asm/dwarf2.h>
+#include <asm/calling.h>
+#include <asm/offset.h>
+#include <asm/msr.h>
+#include <asm/unistd.h>
+#include <asm/thread_info.h>
+#include <asm/hw_irq.h>
+
+ .code64
+
+#ifdef CONFIG_PREEMPT
+#define preempt_stop cli
+#else
+#define preempt_stop
+#define retint_kernel retint_restore_args
+#endif
+
+/*
+ * C code is not supposed to know about undefined top of stack. Every time
+ * a C function with an pt_regs argument is called from the SYSCALL based
+ * fast path FIXUP_TOP_OF_STACK is needed.
+ * RESTORE_TOP_OF_STACK syncs the syscall state after any possible ptregs
+ * manipulation.
+ */
+
+ /* %rsp:at FRAMEEND */
+ .macro FIXUP_TOP_OF_STACK tmp
+ movq %gs:pda_oldrsp,\tmp
+ movq \tmp,RSP(%rsp)
+ movq $__USER_DS,SS(%rsp)
+ movq $__USER_CS,CS(%rsp)
+ movq $-1,RCX(%rsp)
+ movq R11(%rsp),\tmp /* get eflags */
+ movq \tmp,EFLAGS(%rsp)
+ .endm
+
+ .macro RESTORE_TOP_OF_STACK tmp,offset=0
+ movq RSP-\offset(%rsp),\tmp
+ movq \tmp,%gs:pda_oldrsp
+ movq EFLAGS-\offset(%rsp),\tmp
+ movq \tmp,R11-\offset(%rsp)
+ .endm
+
+ .macro FAKE_STACK_FRAME child_rip
+ /* push in order ss, rsp, eflags, cs, rip */
+ xorq %rax, %rax
+ pushq %rax /* ss */
+ CFI_ADJUST_CFA_OFFSET 8
+ pushq %rax /* rsp */
+ CFI_ADJUST_CFA_OFFSET 8
+ CFI_OFFSET rip,0
+ pushq $(1<<9) /* eflags - interrupts on */
+ CFI_ADJUST_CFA_OFFSET 8
+ pushq $__KERNEL_CS /* cs */
+ CFI_ADJUST_CFA_OFFSET 8
+ pushq \child_rip /* rip */
+ CFI_ADJUST_CFA_OFFSET 8
+ CFI_OFFSET rip,0
+ pushq %rax /* orig rax */
+ CFI_ADJUST_CFA_OFFSET 8
+ .endm
+
+ .macro UNFAKE_STACK_FRAME
+ addq $8*6, %rsp
+ CFI_ADJUST_CFA_OFFSET -(6*8)
+ .endm
+
+ .macro CFI_DEFAULT_STACK
+ CFI_ADJUST_CFA_OFFSET (SS)
+ CFI_OFFSET r15,R15-SS
+ CFI_OFFSET r14,R14-SS
+ CFI_OFFSET r13,R13-SS
+ CFI_OFFSET r12,R12-SS
+ CFI_OFFSET rbp,RBP-SS
+ CFI_OFFSET rbx,RBX-SS
+ CFI_OFFSET r11,R11-SS
+ CFI_OFFSET r10,R10-SS
+ CFI_OFFSET r9,R9-SS
+ CFI_OFFSET r8,R8-SS
+ CFI_OFFSET rax,RAX-SS
+ CFI_OFFSET rcx,RCX-SS
+ CFI_OFFSET rdx,RDX-SS
+ CFI_OFFSET rsi,RSI-SS
+ CFI_OFFSET rdi,RDI-SS
+ CFI_OFFSET rsp,RSP-SS
+ CFI_OFFSET rip,RIP-SS
+ .endm
+/*
+ * A newly forked process directly context switches into this.
+ */
+/* rdi: prev */
+ENTRY(ret_from_fork)
+ CFI_STARTPROC
+ CFI_DEFAULT_STACK
+ call schedule_tail
+ GET_THREAD_INFO(%rcx)
+ testl $(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT),threadinfo_flags(%rcx)
+ jnz rff_trace
+rff_action:
+ RESTORE_REST
+ testl $3,CS-ARGOFFSET(%rsp) # from kernel_thread?
+ je int_ret_from_sys_call
+ testl $_TIF_IA32,threadinfo_flags(%rcx)
+ jnz int_ret_from_sys_call
+ RESTORE_TOP_OF_STACK %rdi,ARGOFFSET
+ jmp ret_from_sys_call
+rff_trace:
+ movq %rsp,%rdi
+ call syscall_trace_leave
+ GET_THREAD_INFO(%rcx)
+ jmp rff_action
+ CFI_ENDPROC
+
+/*
+ * System call entry. Upto 6 arguments in registers are supported.
+ *
+ * SYSCALL does not save anything on the stack and does not change the
+ * stack pointer.
+ */
+
+/*
+ * Register setup:
+ * rax system call number
+ * rdi arg0
+ * rcx return address for syscall/sysret, C arg3
+ * rsi arg1
+ * rdx arg2
+ * r10 arg3 (--> moved to rcx for C)
+ * r8 arg4
+ * r9 arg5
+ * r11 eflags for syscall/sysret, temporary for C
+ * r12-r15,rbp,rbx saved by C code, not touched.
+ *
+ * Interrupts are off on entry.
+ * Only called from user space.
+ *
+ * XXX if we had a free scratch register we could save the RSP into the stack frame
+ * and report it properly in ps. Unfortunately we haven't.
+ */
+
+ENTRY(system_call)
+ CFI_STARTPROC
+ swapgs
+ movq %rsp,%gs:pda_oldrsp
+ movq %gs:pda_kernelstack,%rsp
+ sti
+ SAVE_ARGS 8,1
+ movq %rax,ORIG_RAX-ARGOFFSET(%rsp)
+ movq %rcx,RIP-ARGOFFSET(%rsp)
+ GET_THREAD_INFO(%rcx)
+ testl $(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT|_TIF_SECCOMP),threadinfo_flags(%rcx)
+ jnz tracesys
+ cmpq $__NR_syscall_max,%rax
+ ja badsys
+ movq %r10,%rcx
+ call *sys_call_table(,%rax,8) # XXX: rip relative
+ movq %rax,RAX-ARGOFFSET(%rsp)
+/*
+ * Syscall return path ending with SYSRET (fast path)
+ * Has incomplete stack frame and undefined top of stack.
+ */
+ .globl ret_from_sys_call
+ret_from_sys_call:
+ movl $_TIF_WORK_MASK,%edi
+ /* edi: flagmask */
+sysret_check:
+ GET_THREAD_INFO(%rcx)
+ cli
+ movl threadinfo_flags(%rcx),%edx
+ andl %edi,%edx
+ jnz sysret_careful
+ movq RIP-ARGOFFSET(%rsp),%rcx
+ RESTORE_ARGS 0,-ARG_SKIP,1
+ movq %gs:pda_oldrsp,%rsp
+ swapgs
+ sysretq
+
+ /* Handle reschedules */
+ /* edx: work, edi: workmask */
+sysret_careful:
+ bt $TIF_NEED_RESCHED,%edx
+ jnc sysret_signal
+ sti
+ pushq %rdi
+ call schedule
+ popq %rdi
+ jmp sysret_check
+
+ /* Handle a signal */
+sysret_signal:
+ sti
+ testl $(_TIF_SIGPENDING|_TIF_NOTIFY_RESUME|_TIF_SINGLESTEP),%edx
+ jz 1f
+
+ /* Really a signal */
+ /* edx: work flags (arg3) */
+ leaq do_notify_resume(%rip),%rax
+ leaq -ARGOFFSET(%rsp),%rdi # &pt_regs -> arg1
+ xorl %esi,%esi # oldset -> arg2
+ call ptregscall_common
+1: movl $_TIF_NEED_RESCHED,%edi
+ jmp sysret_check
+
+ /* Do syscall tracing */
+tracesys:
+ SAVE_REST
+ movq $-ENOSYS,RAX(%rsp)
+ FIXUP_TOP_OF_STACK %rdi
+ movq %rsp,%rdi
+ call syscall_trace_enter
+ LOAD_ARGS ARGOFFSET /* reload args from stack in case ptrace changed it */
+ RESTORE_REST
+ cmpq $__NR_syscall_max,%rax
+ ja 1f
+ movq %r10,%rcx /* fixup for C */
+ call *sys_call_table(,%rax,8)
+ movq %rax,RAX-ARGOFFSET(%rsp)
+1: SAVE_REST
+ movq %rsp,%rdi
+ call syscall_trace_leave
+ RESTORE_TOP_OF_STACK %rbx
+ RESTORE_REST
+ jmp ret_from_sys_call
+
+badsys:
+ movq $-ENOSYS,RAX-ARGOFFSET(%rsp)
+ jmp ret_from_sys_call
+
+/*
+ * Syscall return path ending with IRET.
+ * Has correct top of stack, but partial stack frame.
+ */
+ENTRY(int_ret_from_sys_call)
+ cli
+ testl $3,CS-ARGOFFSET(%rsp)
+ je retint_restore_args
+ movl $_TIF_ALLWORK_MASK,%edi
+ /* edi: mask to check */
+int_with_check:
+ GET_THREAD_INFO(%rcx)
+ movl threadinfo_flags(%rcx),%edx
+ andl %edi,%edx
+ jnz int_careful
+ jmp retint_swapgs
+
+ /* Either reschedule or signal or syscall exit tracking needed. */
+ /* First do a reschedule test. */
+ /* edx: work, edi: workmask */
+int_careful:
+ bt $TIF_NEED_RESCHED,%edx
+ jnc int_very_careful
+ sti
+ pushq %rdi
+ call schedule
+ popq %rdi
+ jmp int_with_check
+
+ /* handle signals and tracing -- both require a full stack frame */
+int_very_careful:
+ sti
+ SAVE_REST
+ /* Check for syscall exit trace */
+ testl $(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT|_TIF_SINGLESTEP),%edx
+ jz int_signal
+ pushq %rdi
+ leaq 8(%rsp),%rdi # &ptregs -> arg1
+ call syscall_trace_leave
+ popq %rdi
+ btr $TIF_SYSCALL_TRACE,%edi
+ btr $TIF_SYSCALL_AUDIT,%edi
+ btr $TIF_SINGLESTEP,%edi
+ jmp int_restore_rest
+
+int_signal:
+ testl $(_TIF_NOTIFY_RESUME|_TIF_SIGPENDING|_TIF_SINGLESTEP),%edx
+ jz 1f
+ movq %rsp,%rdi # &ptregs -> arg1
+ xorl %esi,%esi # oldset -> arg2
+ call do_notify_resume
+1: movl $_TIF_NEED_RESCHED,%edi
+int_restore_rest:
+ RESTORE_REST
+ jmp int_with_check
+ CFI_ENDPROC
+
+/*
+ * Certain special system calls that need to save a complete full stack frame.
+ */
+
+ .macro PTREGSCALL label,func,arg
+ .globl \label
+\label:
+ leaq \func(%rip),%rax
+ leaq -ARGOFFSET+8(%rsp),\arg /* 8 for return address */
+ jmp ptregscall_common
+ .endm
+
+ PTREGSCALL stub_clone, sys_clone, %r8
+ PTREGSCALL stub_fork, sys_fork, %rdi
+ PTREGSCALL stub_vfork, sys_vfork, %rdi
+ PTREGSCALL stub_rt_sigsuspend, sys_rt_sigsuspend, %rdx
+ PTREGSCALL stub_sigaltstack, sys_sigaltstack, %rdx
+ PTREGSCALL stub_iopl, sys_iopl, %rsi
+
+ENTRY(ptregscall_common)
+ CFI_STARTPROC
+ popq %r11
+ CFI_ADJUST_CFA_OFFSET -8
+ SAVE_REST
+ movq %r11, %r15
+ FIXUP_TOP_OF_STACK %r11
+ call *%rax
+ RESTORE_TOP_OF_STACK %r11
+ movq %r15, %r11
+ RESTORE_REST
+ pushq %r11
+ CFI_ADJUST_CFA_OFFSET 8
+ ret
+ CFI_ENDPROC
+
+ENTRY(stub_execve)
+ CFI_STARTPROC
+ popq %r11
+ CFI_ADJUST_CFA_OFFSET -8
+ SAVE_REST
+ movq %r11, %r15
+ FIXUP_TOP_OF_STACK %r11
+ call sys_execve
+ GET_THREAD_INFO(%rcx)
+ bt $TIF_IA32,threadinfo_flags(%rcx)
+ jc exec_32bit
+ RESTORE_TOP_OF_STACK %r11
+ movq %r15, %r11
+ RESTORE_REST
+ push %r11
+ ret
+
+exec_32bit:
+ CFI_ADJUST_CFA_OFFSET REST_SKIP
+ movq %rax,RAX(%rsp)
+ RESTORE_REST
+ jmp int_ret_from_sys_call
+ CFI_ENDPROC
+
+/*
+ * sigreturn is special because it needs to restore all registers on return.
+ * This cannot be done with SYSRET, so use the IRET return path instead.
+ */
+ENTRY(stub_rt_sigreturn)
+ CFI_STARTPROC
+ addq $8, %rsp
+ SAVE_REST
+ movq %rsp,%rdi
+ FIXUP_TOP_OF_STACK %r11
+ call sys_rt_sigreturn
+ movq %rax,RAX(%rsp) # fixme, this could be done at the higher layer
+ RESTORE_REST
+ jmp int_ret_from_sys_call
+ CFI_ENDPROC
+
+/*
+ * Interrupt entry/exit.
+ *
+ * Interrupt entry points save only callee clobbered registers in fast path.
+ *
+ * Entry runs with interrupts off.
+ */
+
+/* 0(%rsp): interrupt number */
+ .macro interrupt func
+ CFI_STARTPROC simple
+ CFI_DEF_CFA rsp,(SS-RDI)
+ CFI_REL_OFFSET rsp,(RSP-ORIG_RAX)
+ CFI_REL_OFFSET rip,(RIP-ORIG_RAX)
+ cld
+#ifdef CONFIG_DEBUG_INFO
+ SAVE_ALL
+ movq %rsp,%rdi
+ /*
+ * Setup a stack frame pointer. This allows gdb to trace
+ * back to the original stack.
+ */
+ movq %rsp,%rbp
+ CFI_DEF_CFA_REGISTER rbp
+#else
+ SAVE_ARGS
+ leaq -ARGOFFSET(%rsp),%rdi # arg1 for handler
+#endif
+ testl $3,CS(%rdi)
+ je 1f
+ swapgs
+1: addl $1,%gs:pda_irqcount # RED-PEN should check preempt count
+ movq %gs:pda_irqstackptr,%rax
+ cmoveq %rax,%rsp
+ pushq %rdi # save old stack
+ call \func
+ .endm
+
+ENTRY(common_interrupt)
+ interrupt do_IRQ
+ /* 0(%rsp): oldrsp-ARGOFFSET */
+ret_from_intr:
+ popq %rdi
+ cli
+ subl $1,%gs:pda_irqcount
+#ifdef CONFIG_DEBUG_INFO
+ movq RBP(%rdi),%rbp
+#endif
+ leaq ARGOFFSET(%rdi),%rsp
+exit_intr:
+ GET_THREAD_INFO(%rcx)
+ testl $3,CS-ARGOFFSET(%rsp)
+ je retint_kernel
+
+ /* Interrupt came from user space */
+ /*
+ * Has a correct top of stack, but a partial stack frame
+ * %rcx: thread info. Interrupts off.
+ */
+retint_with_reschedule:
+ movl $_TIF_WORK_MASK,%edi
+retint_check:
+ movl threadinfo_flags(%rcx),%edx
+ andl %edi,%edx
+ jnz retint_careful
+retint_swapgs:
+ cli
+ swapgs
+retint_restore_args:
+ cli
+ RESTORE_ARGS 0,8,0
+iret_label:
+ iretq
+
+ .section __ex_table,"a"
+ .quad iret_label,bad_iret
+ .previous
+ .section .fixup,"ax"
+ /* force a signal here? this matches i386 behaviour */
+ /* running with kernel gs */
+bad_iret:
+ movq $-9999,%rdi /* better code? */
+ jmp do_exit
+ .previous
+
+ /* edi: workmask, edx: work */
+retint_careful:
+ bt $TIF_NEED_RESCHED,%edx
+ jnc retint_signal
+ sti
+ pushq %rdi
+ call schedule
+ popq %rdi
+ GET_THREAD_INFO(%rcx)
+ cli
+ jmp retint_check
+
+retint_signal:
+ testl $(_TIF_SIGPENDING|_TIF_NOTIFY_RESUME|_TIF_SINGLESTEP),%edx
+ jz retint_swapgs
+ sti
+ SAVE_REST
+ movq $-1,ORIG_RAX(%rsp)
+ xorq %rsi,%rsi # oldset
+ movq %rsp,%rdi # &pt_regs
+ call do_notify_resume
+ RESTORE_REST
+ cli
+ movl $_TIF_NEED_RESCHED,%edi
+ GET_THREAD_INFO(%rcx)
+ jmp retint_check
+
+#ifdef CONFIG_PREEMPT
+ /* Returning to kernel space. Check if we need preemption */
+ /* rcx: threadinfo. interrupts off. */
+ .p2align
+retint_kernel:
+ cmpl $0,threadinfo_preempt_count(%rcx)
+ jnz retint_restore_args
+ bt $TIF_NEED_RESCHED,threadinfo_flags(%rcx)
+ jnc retint_restore_args
+ bt $9,EFLAGS-ARGOFFSET(%rsp) /* interrupts off? */
+ jnc retint_restore_args
+ call preempt_schedule_irq
+ jmp exit_intr
+#endif
+ CFI_ENDPROC
+
+/*
+ * APIC interrupts.
+ */
+ .macro apicinterrupt num,func
+ pushq $\num-256
+ interrupt \func
+ jmp ret_from_intr
+ CFI_ENDPROC
+ .endm
+
+ENTRY(thermal_interrupt)
+ apicinterrupt THERMAL_APIC_VECTOR,smp_thermal_interrupt
+
+#ifdef CONFIG_SMP
+ENTRY(reschedule_interrupt)
+ apicinterrupt RESCHEDULE_VECTOR,smp_reschedule_interrupt
+
+ENTRY(invalidate_interrupt)
+ apicinterrupt INVALIDATE_TLB_VECTOR,smp_invalidate_interrupt
+
+ENTRY(call_function_interrupt)
+ apicinterrupt CALL_FUNCTION_VECTOR,smp_call_function_interrupt
+#endif
+
+#ifdef CONFIG_X86_LOCAL_APIC
+ENTRY(apic_timer_interrupt)
+ apicinterrupt LOCAL_TIMER_VECTOR,smp_apic_timer_interrupt
+
+ENTRY(error_interrupt)
+ apicinterrupt ERROR_APIC_VECTOR,smp_error_interrupt
+
+ENTRY(spurious_interrupt)
+ apicinterrupt SPURIOUS_APIC_VECTOR,smp_spurious_interrupt
+#endif
+
+/*
+ * Exception entry points.
+ */
+ .macro zeroentry sym
+ pushq $0 /* push error code/oldrax */
+ pushq %rax /* push real oldrax to the rdi slot */
+ leaq \sym(%rip),%rax
+ jmp error_entry
+ .endm
+
+ .macro errorentry sym
+ pushq %rax
+ leaq \sym(%rip),%rax
+ jmp error_entry
+ .endm
+
+ /* error code is on the stack already */
+ /* handle NMI like exceptions that can happen everywhere */
+ .macro paranoidentry sym
+ SAVE_ALL
+ cld
+ movl $1,%ebx
+ movl $MSR_GS_BASE,%ecx
+ rdmsr
+ testl %edx,%edx
+ js 1f
+ swapgs
+ xorl %ebx,%ebx
+1: movq %rsp,%rdi
+ movq ORIG_RAX(%rsp),%rsi
+ movq $-1,ORIG_RAX(%rsp)
+ call \sym
+ .endm
+
+/*
+ * Exception entry point. This expects an error code/orig_rax on the stack
+ * and the exception handler in %rax.
+ */
+ENTRY(error_entry)
+ CFI_STARTPROC simple
+ CFI_DEF_CFA rsp,(SS-RDI)
+ CFI_REL_OFFSET rsp,(RSP-RDI)
+ CFI_REL_OFFSET rip,(RIP-RDI)
+ /* rdi slot contains rax, oldrax contains error code */
+ cld
+ subq $14*8,%rsp
+ CFI_ADJUST_CFA_OFFSET (14*8)
+ movq %rsi,13*8(%rsp)
+ CFI_REL_OFFSET rsi,RSI
+ movq 14*8(%rsp),%rsi /* load rax from rdi slot */
+ movq %rdx,12*8(%rsp)
+ CFI_REL_OFFSET rdx,RDX
+ movq %rcx,11*8(%rsp)
+ CFI_REL_OFFSET rcx,RCX
+ movq %rsi,10*8(%rsp) /* store rax */
+ CFI_REL_OFFSET rax,RAX
+ movq %r8, 9*8(%rsp)
+ CFI_REL_OFFSET r8,R8
+ movq %r9, 8*8(%rsp)
+ CFI_REL_OFFSET r9,R9
+ movq %r10,7*8(%rsp)
+ CFI_REL_OFFSET r10,R10
+ movq %r11,6*8(%rsp)
+ CFI_REL_OFFSET r11,R11
+ movq %rbx,5*8(%rsp)
+ CFI_REL_OFFSET rbx,RBX
+ movq %rbp,4*8(%rsp)
+ CFI_REL_OFFSET rbp,RBP
+ movq %r12,3*8(%rsp)
+ CFI_REL_OFFSET r12,R12
+ movq %r13,2*8(%rsp)
+ CFI_REL_OFFSET r13,R13
+ movq %r14,1*8(%rsp)
+ CFI_REL_OFFSET r14,R14
+ movq %r15,(%rsp)
+ CFI_REL_OFFSET r15,R15
+ xorl %ebx,%ebx
+ testl $3,CS(%rsp)
+ je error_kernelspace
+error_swapgs:
+ swapgs
+error_sti:
+ movq %rdi,RDI(%rsp)
+ movq %rsp,%rdi
+ movq ORIG_RAX(%rsp),%rsi /* get error code */
+ movq $-1,ORIG_RAX(%rsp)
+ call *%rax
+ /* ebx: no swapgs flag (1: don't need swapgs, 0: need it) */
+error_exit:
+ movl %ebx,%eax
+ RESTORE_REST
+ cli
+ GET_THREAD_INFO(%rcx)
+ testl %eax,%eax
+ jne retint_kernel
+ movl threadinfo_flags(%rcx),%edx
+ movl $_TIF_WORK_MASK,%edi
+ andl %edi,%edx
+ jnz retint_careful
+ swapgs
+ RESTORE_ARGS 0,8,0
+ iretq
+ CFI_ENDPROC
+
+error_kernelspace:
+ incl %ebx
+ /* There are two places in the kernel that can potentially fault with
+ usergs. Handle them here. The exception handlers after
+ iret run with kernel gs again, so don't set the user space flag.
+ B stepping K8s sometimes report an truncated RIP for IRET
+ exceptions returning to compat mode. Check for these here too. */
+ leaq iret_label(%rip),%rbp
+ cmpq %rbp,RIP(%rsp)
+ je error_swapgs
+ movl %ebp,%ebp /* zero extend */
+ cmpq %rbp,RIP(%rsp)
+ je error_swapgs
+ cmpq $gs_change,RIP(%rsp)
+ je error_swapgs
+ jmp error_sti
+
+ /* Reload gs selector with exception handling */
+ /* edi: new selector */
+ENTRY(load_gs_index)
+ pushf
+ cli
+ swapgs
+gs_change:
+ movl %edi,%gs
+2: mfence /* workaround */
+ swapgs
+ popf
+ ret
+
+ .section __ex_table,"a"
+ .align 8
+ .quad gs_change,bad_gs
+ .previous
+ .section .fixup,"ax"
+ /* running with kernelgs */
+bad_gs:
+ swapgs /* switch back to user gs */
+ xorl %eax,%eax
+ movl %eax,%gs
+ jmp 2b
+ .previous
+
+/*
+ * Create a kernel thread.
+ *
+ * C extern interface:
+ * extern long kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
+ *
+ * asm input arguments:
+ * rdi: fn, rsi: arg, rdx: flags
+ */
+ENTRY(kernel_thread)
+ CFI_STARTPROC
+ FAKE_STACK_FRAME $child_rip
+ SAVE_ALL
+
+ # rdi: flags, rsi: usp, rdx: will be &pt_regs
+ movq %rdx,%rdi
+ orq kernel_thread_flags(%rip),%rdi
+ movq $-1, %rsi
+ movq %rsp, %rdx
+
+ xorl %r8d,%r8d
+ xorl %r9d,%r9d
+
+ # clone now
+ call do_fork
+ movq %rax,RAX(%rsp)
+ xorl %edi,%edi
+
+ /*
+ * It isn't worth to check for reschedule here,
+ * so internally to the x86_64 port you can rely on kernel_thread()
+ * not to reschedule the child before returning, this avoids the need
+ * of hacks for example to fork off the per-CPU idle tasks.
+ * [Hopefully no generic code relies on the reschedule -AK]
+ */
+ RESTORE_ALL
+ UNFAKE_STACK_FRAME
+ ret
+ CFI_ENDPROC
+
+
+child_rip:
+ /*
+ * Here we are in the child and the registers are set as they were
+ * at kernel_thread() invocation in the parent.
+ */
+ movq %rdi, %rax
+ movq %rsi, %rdi
+ call *%rax
+ # exit
+ xorq %rdi, %rdi
+ call do_exit
+
+/*
+ * execve(). This function needs to use IRET, not SYSRET, to set up all state properly.
+ *
+ * C extern interface:
+ * extern long execve(char *name, char **argv, char **envp)
+ *
+ * asm input arguments:
+ * rdi: name, rsi: argv, rdx: envp
+ *
+ * We want to fallback into:
+ * extern long sys_execve(char *name, char **argv,char **envp, struct pt_regs regs)
+ *
+ * do_sys_execve asm fallback arguments:
+ * rdi: name, rsi: argv, rdx: envp, fake frame on the stack
+ */
+ENTRY(execve)
+ CFI_STARTPROC
+ FAKE_STACK_FRAME $0
+ SAVE_ALL
+ call sys_execve
+ movq %rax, RAX(%rsp)
+ RESTORE_REST
+ testq %rax,%rax
+ je int_ret_from_sys_call
+ RESTORE_ARGS
+ UNFAKE_STACK_FRAME
+ ret
+ CFI_ENDPROC
+
+ENTRY(page_fault)
+ errorentry do_page_fault
+
+ENTRY(coprocessor_error)
+ zeroentry do_coprocessor_error
+
+ENTRY(simd_coprocessor_error)
+ zeroentry do_simd_coprocessor_error
+
+ENTRY(device_not_available)
+ zeroentry math_state_restore
+
+ /* runs on exception stack */
+ENTRY(debug)
+ CFI_STARTPROC
+ pushq $0
+ CFI_ADJUST_CFA_OFFSET 8
+ paranoidentry do_debug
+ /* switch back to process stack to restore the state ptrace touched */
+ movq %rax,%rsp
+ testl $3,CS(%rsp)
+ jnz paranoid_userspace
+ jmp paranoid_exit
+ CFI_ENDPROC
+
+ /* runs on exception stack */
+ENTRY(nmi)
+ CFI_STARTPROC
+ pushq $-1
+ CFI_ADJUST_CFA_OFFSET 8
+ paranoidentry do_nmi
+ /* ebx: no swapgs flag */
+paranoid_exit:
+ testl %ebx,%ebx /* swapgs needed? */
+ jnz paranoid_restore
+paranoid_swapgs:
+ cli
+ swapgs
+paranoid_restore:
+ RESTORE_ALL 8
+ iretq
+paranoid_userspace:
+ cli
+ GET_THREAD_INFO(%rcx)
+ movl threadinfo_flags(%rcx),%edx
+ testl $_TIF_NEED_RESCHED,%edx
+ jnz paranoid_resched
+ testl $(_TIF_SIGPENDING|_TIF_NOTIFY_RESUME|_TIF_SINGLESTEP),%edx
+ jnz paranoid_signal
+ jmp paranoid_swapgs
+paranoid_resched:
+ sti
+ call schedule
+ jmp paranoid_exit
+paranoid_signal:
+ sti
+ xorl %esi,%esi /* oldset */
+ movq %rsp,%rdi /* &pt_regs */
+ call do_notify_resume
+ jmp paranoid_exit
+ CFI_ENDPROC
+
+ENTRY(int3)
+ zeroentry do_int3
+
+ENTRY(overflow)
+ zeroentry do_overflow
+
+ENTRY(bounds)
+ zeroentry do_bounds
+
+ENTRY(invalid_op)
+ zeroentry do_invalid_op
+
+ENTRY(coprocessor_segment_overrun)
+ zeroentry do_coprocessor_segment_overrun
+
+ENTRY(reserved)
+ zeroentry do_reserved
+
+ /* runs on exception stack */
+ENTRY(double_fault)
+ CFI_STARTPROC
+ paranoidentry do_double_fault
+ movq %rax,%rsp
+ testl $3,CS(%rsp)
+ jnz paranoid_userspace
+ jmp paranoid_exit
+ CFI_ENDPROC
+
+ENTRY(invalid_TSS)
+ errorentry do_invalid_TSS
+
+ENTRY(segment_not_present)
+ errorentry do_segment_not_present
+
+ /* runs on exception stack */
+ENTRY(stack_segment)
+ CFI_STARTPROC
+ paranoidentry do_stack_segment
+ movq %rax,%rsp
+ testl $3,CS(%rsp)
+ jnz paranoid_userspace
+ jmp paranoid_exit
+ CFI_ENDPROC
+
+ENTRY(general_protection)
+ errorentry do_general_protection
+
+ENTRY(alignment_check)
+ errorentry do_alignment_check
+
+ENTRY(divide_error)
+ zeroentry do_divide_error
+
+ENTRY(spurious_interrupt_bug)
+ zeroentry do_spurious_interrupt_bug
+
+#ifdef CONFIG_X86_MCE
+ /* runs on exception stack */
+ENTRY(machine_check)
+ CFI_STARTPROC
+ pushq $0
+ CFI_ADJUST_CFA_OFFSET 8
+ paranoidentry do_machine_check
+ jmp paranoid_exit
+ CFI_ENDPROC
+#endif
+
+ENTRY(call_debug)
+ zeroentry do_call_debug
+