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author | Stas Sergeev <stsp@aknet.ru> | 2006-12-07 02:14:01 +0100 |
---|---|---|
committer | Andi Kleen <andi@basil.nowhere.org> | 2006-12-07 02:14:01 +0100 |
commit | be44d2aabce2d62f72d5751d1871b6212bf7a1c7 (patch) | |
tree | 3f190dd5b5747ee83b50c4596b4801ce6c6b551c /arch/i386/kernel/entry.S | |
parent | bb81a09e55eaf7e5f798468ab971469b6f66a259 (diff) | |
download | kernel_samsung_espresso10-be44d2aabce2d62f72d5751d1871b6212bf7a1c7.zip kernel_samsung_espresso10-be44d2aabce2d62f72d5751d1871b6212bf7a1c7.tar.gz kernel_samsung_espresso10-be44d2aabce2d62f72d5751d1871b6212bf7a1c7.tar.bz2 |
[PATCH] i386: espfix cleanup
Clean up the espfix code:
- Introduced PER_CPU() macro to be used from asm
- Introduced GET_DESC_BASE() macro to be used from asm
- Rewrote the fixup code in asm, as calling a C code with the altered %ss
appeared to be unsafe
- No longer altering the stack from a .fixup section
- 16bit per-cpu stack is no longer used, instead the stack segment base
is patched the way so that the high word of the kernel and user %esp
are the same.
- Added the limit-patching for the espfix segment. (Chuck Ebbert)
[jeremy@goop.org: use the x86 scaling addressing mode rather than shifting]
Signed-off-by: Stas Sergeev <stsp@aknet.ru>
Signed-off-by: Andi Kleen <ak@suse.de>
Acked-by: Zachary Amsden <zach@vmware.com>
Acked-by: Chuck Ebbert <76306.1226@compuserve.com>
Acked-by: Jan Beulich <jbeulich@novell.com>
Cc: Andi Kleen <ak@muc.de>
Signed-off-by: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Diffstat (limited to 'arch/i386/kernel/entry.S')
-rw-r--r-- | arch/i386/kernel/entry.S | 73 |
1 files changed, 33 insertions, 40 deletions
diff --git a/arch/i386/kernel/entry.S b/arch/i386/kernel/entry.S index 5a63d6f..c38d801 100644 --- a/arch/i386/kernel/entry.S +++ b/arch/i386/kernel/entry.S @@ -48,6 +48,7 @@ #include <asm/smp.h> #include <asm/page.h> #include <asm/desc.h> +#include <asm/percpu.h> #include <asm/dwarf2.h> #include "irq_vectors.h" @@ -418,23 +419,18 @@ ldt_ss: * 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 + movl 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 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 @@ -524,30 +520,30 @@ syscall_badsys: 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 :( */ \ + GET_THREAD_INFO(%ebp); \ + movl TI_cpu(%ebp), %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 @@ -614,7 +610,6 @@ error_code: 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 +622,6 @@ 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 @@ -644,7 +638,7 @@ error_code: /*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 $-1, ORIG_EAX(%esp) movl %ecx, ES(%esp) /*CFI_REL_OFFSET es, ES*/ movl $(__USER_DS), %ecx @@ -754,7 +748,7 @@ 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 +791,7 @@ 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 +800,6 @@ 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 +810,11 @@ 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" |