diff options
Diffstat (limited to 'arch/i386/kernel/entry.S')
| -rw-r--r-- | arch/i386/kernel/entry.S | 130 |
1 files changed, 106 insertions, 24 deletions
diff --git a/arch/i386/kernel/entry.S b/arch/i386/kernel/entry.S index 87aad70d37302..1e45ff292bc99 100644 --- a/arch/i386/kernel/entry.S +++ b/arch/i386/kernel/entry.S @@ -47,6 +47,7 @@ #include <asm/segment.h> #include <asm/smp.h> #include <asm/page.h> +#include <asm/desc.h> #include "irq_vectors.h" #define nr_syscalls ((syscall_table_size)/4) @@ -78,7 +79,7 @@ VM_MASK = 0x00020000 #define preempt_stop cli #else #define preempt_stop -#define resume_kernel restore_all +#define resume_kernel restore_nocheck #endif #define SAVE_ALL \ @@ -122,24 +123,6 @@ VM_MASK = 0x00020000 .previous -#define RESTORE_ALL \ - RESTORE_REGS \ - addl $4, %esp; \ -1: iret; \ -.section .fixup,"ax"; \ -2: sti; \ - movl $(__USER_DS), %edx; \ - movl %edx, %ds; \ - movl %edx, %es; \ - movl $11,%eax; \ - call do_exit; \ -.previous; \ -.section __ex_table,"a";\ - .align 4; \ - .long 1b,2b; \ -.previous - - ENTRY(ret_from_fork) pushl %eax call schedule_tail @@ -163,7 +146,7 @@ ret_from_intr: movl EFLAGS(%esp), %eax # mix EFLAGS and CS movb CS(%esp), %al testl $(VM_MASK | 3), %eax - jz resume_kernel # returning to kernel or vm86-space + jz resume_kernel ENTRY(resume_userspace) cli # make sure we don't miss an interrupt # setting need_resched or sigpending @@ -178,7 +161,7 @@ ENTRY(resume_userspace) ENTRY(resume_kernel) cli cmpl $0,TI_preempt_count(%ebp) # non-zero preempt_count ? - jnz restore_all + jnz restore_nocheck need_resched: movl TI_flags(%ebp), %ecx # need_resched set ? testb $_TIF_NEED_RESCHED, %cl @@ -259,8 +242,56 @@ syscall_exit: movl TI_flags(%ebp), %ecx testw $_TIF_ALLWORK_MASK, %cx # current->work jne syscall_exit_work + restore_all: - RESTORE_ALL + movl EFLAGS(%esp), %eax # mix EFLAGS, SS and CS + movb OLDSS(%esp), %ah + movb CS(%esp), %al + andl $(VM_MASK | (4 << 8) | 3), %eax + cmpl $((4 << 8) | 3), %eax + je ldt_ss # returning to user-space with LDT SS +restore_nocheck: + RESTORE_REGS + addl $4, %esp +1: iret +.section .fixup,"ax" +iret_exc: + sti + movl $__USER_DS, %edx + movl %edx, %ds + movl %edx, %es + movl $11,%eax + call do_exit +.previous +.section __ex_table,"a" + .align 4 + .long 1b,iret_exc +.previous + +ldt_ss: + larl OLDSS(%esp), %eax + jnz restore_nocheck + testl $0x00400000, %eax # returning to 32bit stack? + jnz restore_nocheck # allright, normal return + /* 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 + cli + 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 + RESTORE_REGS + lss 20+4(%esp), %esp # switch to 16bit stack +1: iret +.section __ex_table,"a" + .align 4 + .long 1b,iret_exc +.previous # perform work that needs to be done immediately before resumption ALIGN @@ -336,6 +367,27 @@ syscall_badsys: movl $-ENOSYS,EAX(%esp) jmp resume_userspace +#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 \ + pushl %eax; \ + movl %ss, %eax; \ + /* see if on 16bit stack */ \ + cmpw $__ESPFIX_SS, %ax; \ + jne 28f; \ + movl $__KERNEL_DS, %edx; \ + movl %edx, %ds; \ + movl %edx, %es; \ + /* switch to 32bit stack */ \ + FIXUP_ESPFIX_STACK \ +28: popl %eax; + /* * Build the entry stubs and pointer table with * some assembler magic. @@ -390,7 +442,9 @@ error_code: pushl %ecx pushl %ebx cld - movl %es, %ecx + pushl %es + UNWIND_ESPFIX_STACK + popl %ecx movl ES(%esp), %edi # get the function address movl ORIG_EAX(%esp), %edx # get the error code movl %eax, ORIG_EAX(%esp) @@ -472,6 +526,11 @@ debug_stack_correct: * fault happened on the sysenter path. */ ENTRY(nmi) + pushl %eax + movl %ss, %eax + cmpw $__ESPFIX_SS, %ax + popl %eax + je nmi_16bit_stack cmpl $sysenter_entry,(%esp) je nmi_stack_fixup pushl %eax @@ -491,7 +550,7 @@ nmi_stack_correct: xorl %edx,%edx # zero error code movl %esp,%eax # pt_regs pointer call do_nmi - RESTORE_ALL + jmp restore_all nmi_stack_fixup: FIX_STACK(12,nmi_stack_correct, 1) @@ -507,6 +566,29 @@ nmi_debug_stack_fixup: FIX_STACK(24,nmi_stack_correct, 1) jmp nmi_stack_correct +nmi_16bit_stack: + /* create the pointer to lss back */ + pushl %ss + pushl %esp + movzwl %sp, %esp + addw $4, (%esp) + /* copy the iret frame of 12 bytes */ + .rept 3 + pushl 16(%esp) + .endr + pushl %eax + SAVE_ALL + FIXUP_ESPFIX_STACK # %eax == %esp + xorl %edx,%edx # zero error code + call do_nmi + RESTORE_REGS + lss 12+4(%esp), %esp # back to 16bit stack +1: iret +.section __ex_table,"a" + .align 4 + .long 1b,iret_exc +.previous + ENTRY(int3) pushl $-1 # mark this as an int SAVE_ALL |