From fd51f666fa591294bd7462447512666e61c56ea0 Mon Sep 17 00:00:00 2001 From: "H. J. Lu" Date: Sun, 1 May 2005 08:58:48 -0700 Subject: [PATCH] [PATCH] i386/x86_64 segment register access update The new i386/x86_64 assemblers no longer accept instructions for moving between a segment register and a 32bit memory location, i.e., movl (%eax),%ds movl %ds,(%eax) To generate instructions for moving between a segment register and a 16bit memory location without the 16bit operand size prefix, 0x66, mov (%eax),%ds mov %ds,(%eax) should be used. It will work with both new and old assemblers. The assembler starting from 2.16.90.0.1 will also support movw (%eax),%ds movw %ds,(%eax) without the 0x66 prefix. I am enclosing patches for 2.4 and 2.6 kernels here. The resulting kernel binaries should be unchanged as before, with old and new assemblers, if gcc never generates memory access for unsigned gsindex; asm volatile("movl %%gs,%0" : "=g" (gsindex)); If gcc does generate memory access for the code above, the upper bits in gsindex are undefined and the new assembler doesn't allow it. Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/i386/kernel/process.c | 4 ++-- arch/i386/kernel/vm86.c | 4 ++-- arch/x86_64/kernel/process.c | 12 ++++++------ include/asm-i386/system.h | 6 +++--- 4 files changed, 13 insertions(+), 13 deletions(-) diff --git a/arch/i386/kernel/process.c b/arch/i386/kernel/process.c index b2203e21acb3..85bd56d44314 100644 --- a/arch/i386/kernel/process.c +++ b/arch/i386/kernel/process.c @@ -611,8 +611,8 @@ struct task_struct fastcall * __switch_to(struct task_struct *prev_p, struct tas * Save away %fs and %gs. No need to save %es and %ds, as * those are always kernel segments while inside the kernel. */ - asm volatile("movl %%fs,%0":"=m" (*(int *)&prev->fs)); - asm volatile("movl %%gs,%0":"=m" (*(int *)&prev->gs)); + asm volatile("mov %%fs,%0":"=m" (prev->fs)); + asm volatile("mov %%gs,%0":"=m" (prev->gs)); /* * Restore %fs and %gs if needed. diff --git a/arch/i386/kernel/vm86.c b/arch/i386/kernel/vm86.c index 2f3d52dacff7..d16cd3738a48 100644 --- a/arch/i386/kernel/vm86.c +++ b/arch/i386/kernel/vm86.c @@ -294,8 +294,8 @@ static void do_sys_vm86(struct kernel_vm86_struct *info, struct task_struct *tsk */ info->regs32->eax = 0; tsk->thread.saved_esp0 = tsk->thread.esp0; - asm volatile("movl %%fs,%0":"=m" (tsk->thread.saved_fs)); - asm volatile("movl %%gs,%0":"=m" (tsk->thread.saved_gs)); + asm volatile("mov %%fs,%0":"=m" (tsk->thread.saved_fs)); + asm volatile("mov %%gs,%0":"=m" (tsk->thread.saved_gs)); tss = &per_cpu(init_tss, get_cpu()); tsk->thread.esp0 = (unsigned long) &info->VM86_TSS_ESP0; diff --git a/arch/x86_64/kernel/process.c b/arch/x86_64/kernel/process.c index 9922d2ba24a3..761b6d35e338 100644 --- a/arch/x86_64/kernel/process.c +++ b/arch/x86_64/kernel/process.c @@ -402,10 +402,10 @@ int copy_thread(int nr, unsigned long clone_flags, unsigned long rsp, p->thread.fs = me->thread.fs; p->thread.gs = me->thread.gs; - asm("movl %%gs,%0" : "=m" (p->thread.gsindex)); - asm("movl %%fs,%0" : "=m" (p->thread.fsindex)); - asm("movl %%es,%0" : "=m" (p->thread.es)); - asm("movl %%ds,%0" : "=m" (p->thread.ds)); + asm("mov %%gs,%0" : "=m" (p->thread.gsindex)); + asm("mov %%fs,%0" : "=m" (p->thread.fsindex)); + asm("mov %%es,%0" : "=m" (p->thread.es)); + asm("mov %%ds,%0" : "=m" (p->thread.ds)); if (unlikely(me->thread.io_bitmap_ptr != NULL)) { p->thread.io_bitmap_ptr = kmalloc(IO_BITMAP_BYTES, GFP_KERNEL); @@ -468,11 +468,11 @@ struct task_struct *__switch_to(struct task_struct *prev_p, struct task_struct * * Switch DS and ES. * This won't pick up thread selector changes, but I guess that is ok. */ - asm volatile("movl %%es,%0" : "=m" (prev->es)); + asm volatile("mov %%es,%0" : "=m" (prev->es)); if (unlikely(next->es | prev->es)) loadsegment(es, next->es); - asm volatile ("movl %%ds,%0" : "=m" (prev->ds)); + asm volatile ("mov %%ds,%0" : "=m" (prev->ds)); if (unlikely(next->ds | prev->ds)) loadsegment(ds, next->ds); diff --git a/include/asm-i386/system.h b/include/asm-i386/system.h index 6f74d4c44a0e..3db717a244f0 100644 --- a/include/asm-i386/system.h +++ b/include/asm-i386/system.h @@ -81,7 +81,7 @@ static inline unsigned long _get_base(char * addr) #define loadsegment(seg,value) \ asm volatile("\n" \ "1:\t" \ - "movl %0,%%" #seg "\n" \ + "mov %0,%%" #seg "\n" \ "2:\n" \ ".section .fixup,\"ax\"\n" \ "3:\t" \ @@ -93,13 +93,13 @@ static inline unsigned long _get_base(char * addr) ".align 4\n\t" \ ".long 1b,3b\n" \ ".previous" \ - : :"m" (*(unsigned int *)&(value))) + : :"m" (value)) /* * Save a segment register away */ #define savesegment(seg, value) \ - asm volatile("movl %%" #seg ",%0":"=m" (*(int *)&(value))) + asm volatile("mov %%" #seg ",%0":"=m" (value)) /* * Clear and set 'TS' bit respectively -- 2.20.1