From 38e9e81f4c81c75799b002d5811de7241b307676 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Mon, 28 Aug 2017 08:47:41 +0200 Subject: x86/gdt: Use bitfields for initialization The GDT entry related code uses two ways to access entries via union fields: - bitfields - macros which initialize the two 16-bit parts of the entry by magic shift and mask operations. Clean it up and only use the bitfields to initialize and access entries. ( The old access patterns were partly done due to GCC optimizing bitfield accesses in a horrible way - that's mostly fixed these days and clarity of code in such low level accessors is very important. ) Signed-off-by: Thomas Gleixner Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Josh Poimboeuf Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Steven Rostedt Link: http://lkml.kernel.org/r/20170828064958.197673367@linutronix.de Signed-off-by: Ingo Molnar --- arch/x86/include/asm/desc.h | 26 ++++++++++++++++---------- 1 file changed, 16 insertions(+), 10 deletions(-) (limited to 'arch/x86/include/asm/desc.h') diff --git a/arch/x86/include/asm/desc.h b/arch/x86/include/asm/desc.h index 0731064c633b..2090cd223505 100644 --- a/arch/x86/include/asm/desc.h +++ b/arch/x86/include/asm/desc.h @@ -23,7 +23,7 @@ static inline void fill_ldt(struct desc_struct *desc, const struct user_desc *in desc->s = 1; desc->dpl = 0x3; desc->p = info->seg_not_present ^ 1; - desc->limit = (info->limit & 0xf0000) >> 16; + desc->limit1 = (info->limit & 0xf0000) >> 16; desc->avl = info->useable; desc->d = info->seg_32bit; desc->g = info->limit_in_pages; @@ -170,14 +170,20 @@ static inline void pack_descriptor(struct desc_struct *desc, unsigned long base, unsigned long limit, unsigned char type, unsigned char flags) { - desc->a = ((base & 0xffff) << 16) | (limit & 0xffff); - desc->b = (base & 0xff000000) | ((base & 0xff0000) >> 16) | - (limit & 0x000f0000) | ((type & 0xff) << 8) | - ((flags & 0xf) << 20); - desc->p = 1; + desc->limit0 = (u16) limit; + desc->base0 = (u16) base; + desc->base1 = (base >> 16) & 0xFF; + desc->type = type & 0x0F; + desc->s = 0; + desc->dpl = 0; + desc->p = 1; + desc->limit1 = (limit >> 16) & 0xF; + desc->avl = (flags >> 0) & 0x01; + desc->l = (flags >> 1) & 0x01; + desc->d = (flags >> 2) & 0x01; + desc->g = (flags >> 3) & 0x01; } - static inline void set_tssldt_descriptor(void *d, unsigned long addr, unsigned type, unsigned size) { @@ -195,7 +201,7 @@ static inline void set_tssldt_descriptor(void *d, unsigned long addr, desc->base2 = (addr >> 24) & 0xFF; desc->base3 = (u32) (addr >> 32); #else - pack_descriptor((struct desc_struct *)d, addr, size, 0x80 | type, 0); + pack_descriptor((struct desc_struct *)d, addr, size, type, 0); #endif } @@ -395,13 +401,13 @@ static inline void set_desc_base(struct desc_struct *desc, unsigned long base) static inline unsigned long get_desc_limit(const struct desc_struct *desc) { - return desc->limit0 | (desc->limit << 16); + return desc->limit0 | (desc->limit1 << 16); } static inline void set_desc_limit(struct desc_struct *desc, unsigned long limit) { desc->limit0 = limit & 0xffff; - desc->limit = (limit >> 16) & 0xf; + desc->limit1 = (limit >> 16) & 0xf; } #ifdef CONFIG_X86_64 -- cgit v1.2.3