Author: kib
Date: Tue Dec 7 12:44:33 2010
New Revision: 216255
URL: http://svn.freebsd.org/changeset/base/216255
Log:
Update some comments related to use of amd64 full context switch.
In exec_linux_setregs(), use locally cached pointer to pcb to set
pcb_full_iret.
In set_regs(), note that full return is needed when code that sets
segment registers is enabled.
MFC after: 1 week
Modified:
head/sys/amd64/amd64/machdep.c
head/sys/amd64/amd64/vm_machdep.c
head/sys/amd64/linux32/linux32_sysvec.c
Modified: head/sys/amd64/amd64/machdep.c
==============================================================================
--- head/sys/amd64/amd64/machdep.c Tue Dec 7 12:25:26 2010
(r216254)
+++ head/sys/amd64/amd64/machdep.c Tue Dec 7 12:44:33 2010
(r216255)
@@ -1906,6 +1906,7 @@ set_regs(struct thread *td, struct reg *
tp->tf_fs = regs->r_fs;
tp->tf_gs = regs->r_gs;
tp->tf_flags = TF_HASSEGS;
+ td->td_pcb->pcb_full_iret = 1;
}
return (0);
}
Modified: head/sys/amd64/amd64/vm_machdep.c
==============================================================================
--- head/sys/amd64/amd64/vm_machdep.c Tue Dec 7 12:25:26 2010
(r216254)
+++ head/sys/amd64/amd64/vm_machdep.c Tue Dec 7 12:44:33 2010
(r216255)
@@ -339,10 +339,9 @@ cpu_set_syscall_retval(struct thread *td
* Reconstruct pc, we know that 'syscall' is 2 bytes,
* lcall $X,y is 7 bytes, int 0x80 is 2 bytes.
* We saved this in tf_err.
- * We have to do a full context restore so that %r10
- * (which was holding the value of %rcx) is restored
+ * %r10 (which was holding the value of %rcx) is restored
* for the next iteration.
- * r10 restore is only required for freebsd/amd64 processes,
+ * %r10 restore is only required for freebsd/amd64 processes,
* but shall be innocent for any ia32 ABI.
*/
td->td_frame->tf_rip -= td->td_frame->tf_err;
Modified: head/sys/amd64/linux32/linux32_sysvec.c
==============================================================================
--- head/sys/amd64/linux32/linux32_sysvec.c Tue Dec 7 12:25:26 2010
(r216254)
+++ head/sys/amd64/linux32/linux32_sysvec.c Tue Dec 7 12:44:33 2010
(r216255)
@@ -865,13 +865,13 @@ exec_linux_setregs(struct thread *td, st
regs->tf_flags = TF_HASSEGS;
regs->tf_cs = _ucode32sel;
regs->tf_rbx = imgp->ps_strings;
- td->td_pcb->pcb_full_iret = 1;
load_cr0(rcr0() | CR0_MP | CR0_TS);
fpstate_drop(td);
- /* Return via doreti so that we can change to a different %cs */
+ /* Do full restore on return so that we can change to a different %cs */
pcb->pcb_flags |= PCB_32BIT;
pcb->pcb_flags &= ~PCB_GS32BIT;
+ pcb->pcb_full_iret = 1;
td->td_retval[1] = 0;
}
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