From be44d2aabce2d62f72d5751d1871b6212bf7a1c7 Mon Sep 17 00:00:00 2001 From: Stas Sergeev Date: Thu, 7 Dec 2006 02:14:01 +0100 Subject: [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 Signed-off-by: Andi Kleen Acked-by: Zachary Amsden Acked-by: Chuck Ebbert <76306.1226@compuserve.com> Acked-by: Jan Beulich Cc: Andi Kleen Signed-off-by: Jeremy Fitzhardinge Signed-off-by: Andrew Morton --- include/asm-i386/desc.h | 27 +++++++++++++++++++++++---- 1 file changed, 23 insertions(+), 4 deletions(-) (limited to 'include/asm-i386/desc.h') diff --git a/include/asm-i386/desc.h b/include/asm-i386/desc.h index a0398f780ca..6cf2ac2bfde 100644 --- a/include/asm-i386/desc.h +++ b/include/asm-i386/desc.h @@ -4,8 +4,6 @@ #include #include -#define CPU_16BIT_STACK_SIZE 1024 - #ifndef __ASSEMBLY__ #include @@ -16,8 +14,6 @@ extern struct desc_struct cpu_gdt_table[GDT_ENTRIES]; -DECLARE_PER_CPU(unsigned char, cpu_16bit_stack[CPU_16BIT_STACK_SIZE]); - struct Xgt_desc_struct { unsigned short size; unsigned long address __attribute__((packed)); @@ -181,6 +177,29 @@ static inline unsigned long get_desc_base(unsigned long *desc) return base; } +#else /* __ASSEMBLY__ */ + +/* + * GET_DESC_BASE reads the descriptor base of the specified segment. + * + * Args: + * idx - descriptor index + * gdt - GDT pointer + * base - 32bit register to which the base will be written + * lo_w - lo word of the "base" register + * lo_b - lo byte of the "base" register + * hi_b - hi byte of the low word of the "base" register + * + * Example: + * GET_DESC_BASE(GDT_ENTRY_ESPFIX_SS, %ebx, %eax, %ax, %al, %ah) + * Will read the base address of GDT_ENTRY_ESPFIX_SS and put it into %eax. + */ +#define GET_DESC_BASE(idx, gdt, base, lo_w, lo_b, hi_b) \ + movb idx*8+4(gdt), lo_b; \ + movb idx*8+7(gdt), hi_b; \ + shll $16, base; \ + movw idx*8+2(gdt), lo_w; + #endif /* !__ASSEMBLY__ */ #endif -- cgit v1.2.2