- Move the init of %gs and pcb_gs before user_ldt_free().

- Always call load_gs()
- Trim comments.

This addresses some of the issues raised by BDE.

1 files changed, 4 insertions, 13 deletions

diff --git a/sys/i386/i386/machdep.c b/sys/i386/i386/machdep.c
index fcf7434..fb3603d 100644
--- a/sys/i386/i386/machdep.c
+++ b/sys/i386/i386/machdep.c
@@ -853,6 +853,10 @@ exec_setregs(td, entry, stack, ps_strings)
 	struct trapframe *regs = td->td_frame;
 	struct pcb *pcb = td->td_pcb;
 
+	/* Reset pc->pcb_gs and %gs before possibly invalidating it. */
+	pcb->pcb_gs = _udatasel;
+	load_gs(_udatasel);
+
 	if (td->td_proc->p_md.md_ldt)
 		user_ldt_free(td);
   
@@ -869,19 +873,6 @@ exec_setregs(td, entry, stack, ps_strings)
 	/* PS_STRINGS value for BSD/OS binaries.  It is 0 for non-BSD/OS. */
 	regs->tf_ebx = ps_strings;
 
-	/* reset %gs as well */
-	if (pcb == PCPU_GET(curpcb))
-		load_gs(_udatasel);
-
-	/*
-	 * Always reset pcb->pcb_gs to udatasel, it will be loaded into gs
-	 * by cpu_switch_load_gs when this process returns from the system
-	 * call. Failing to reset pcb_gs here can cause cpu_switch_load_gs
-	 * to trigger a general protection fault if the parent process had
-	 * modified gs to point at a LDT entry.
-	 */
-	pcb->pcb_gs = _udatasel;
-
         /*
          * Reset the hardware debug registers if they were in use.
          * They won't have any meaning for the newly exec'd process.