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Small optimization.

This commit is contained in:
mycroft 1994-04-15 07:15:27 +00:00
parent 2a83433d4e
commit d800da55ea
1 changed files with 39 additions and 17 deletions
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56
sys/arch/i386/i386/machdep.c
View File

@ -36,7 +36,7 @@
* SUCH DAMAGE.
*
* from: @(#)machdep.c 7.4 (Berkeley) 6/3/91
* $Id: machdep.c,v 1.98 1994/04/15 07:04:22 cgd Exp $
* $Id: machdep.c,v 1.99 1994/04/15 07:15:27 mycroft Exp $
*/
#include <stddef.h>
@ -466,12 +466,44 @@ sendsig(catcher, sig, mask, code)
}
static __inline int
verr(u_short sel)
check_selectors(u_short cs, u_short ss, u_short ds, u_short es)
{
int eflags;
int result;
__asm __volatile("verr %1\n\tlahf" : "=a" (eflags) : "g" (sel));
return (eflags & (PSL_Z << 8));
__asm __volatile("
movl %1,%%edx
verr %%dx
jnz 1f
movl %%edx,%%eax
movl %2,%%edx
verr %%dx
jnz 1f
andl %%edx,%%eax
movl %3,%%edx
verr %%dx
jz 2f
testl $0xfffc,%%edx
jnz 1f
2: andl %%edx,%%eax
movl %4,%%edx
verr %%dx
jz 2f
testl $0xfffc,%%edx
jnz 1f
2: andl %%edx,%%eax
andl $3,%%eax
subl $3,%%eax
jmp 3f
1: movl $1,%%eax
3:
": "=a" (result)
: "g" (cs), "g" (ss), "g" (ds), "g" (es)
: "%edx");
return result;
}
/*
@ -528,22 +560,12 @@ sigreturn(p, uap, retval)
* none of the segments we wish to protect are conforming. (If they
* were, this check wouldn't help much anyway.)
*/
#define valid_sel(sel) \
(ISPL(sel) == SEL_UPL && verr(sel))
#define null_sel(sel) \
(!ISLDT(sel) && IDXSEL(sel) == 0)
if (!valid_sel(context.sc_cs) || !valid_sel(context.sc_ss) ||
(!valid_sel(context.sc_ds) && !null_sel(context.sc_ds)) ||
(!valid_sel(context.sc_es) && !null_sel(context.sc_es))) {
if (check_selectors(context.sc_cs, context.sc_ss, context.sc_ds,
context.sc_es)) {
trapsignal(p, SIGBUS, T_PROTFLT);
return(EINVAL);
}
#undef valid_sel
#undef null_sel
p->p_sigacts->ps_onstack = context.sc_onstack & 01;
p->p_sigmask = context.sc_mask &~
(sigmask(SIGKILL)|sigmask(SIGCONT)|sigmask(SIGSTOP));