svn commit: r213382 - head/sys/amd64/amd64
Konstantin Belousov
kib at FreeBSD.org
Sun Oct 3 13:52:18 UTC 2010
Author: kib
Date: Sun Oct 3 13:52:17 2010
New Revision: 213382
URL: http://svn.freebsd.org/changeset/base/213382
Log:
The makectx() function, used by kdb_trap() to reconstruct pcb from
trap frame when trap initiated kdb entry, incorrectly calculated the
value of %rsp for trapped thread.
According to Intel(R) 64 and IA-32 Architectures Software Developer's Manual
Volume 3A: System Programming Guide, Part 1, rev. 035, 6.14.2 64-Bit Mode
Stack Frame, "64-bit mode ... pushes SS:RSP unconditionally, rather than
only on a CPL change."
Even assuming the conditional push of the %ss:%rsp, the calculation
was still wrong because sizeof(tf_ss) + sizeof(tf_rsp) == 16 on amd64.
Always use the tf_rsp from trap frame. The change supposedly fixes
stepping when using kgdb backend for kdb.
Submitted by: Zhouyi Zhou <zhouzhouyi gmail com>
PR: amd64/151167
Reviewed by: avg
MFC after: 1 week
Modified:
head/sys/amd64/amd64/machdep.c
Modified: head/sys/amd64/amd64/machdep.c
==============================================================================
--- head/sys/amd64/amd64/machdep.c Sun Oct 3 13:13:10 2010 (r213381)
+++ head/sys/amd64/amd64/machdep.c Sun Oct 3 13:52:17 2010 (r213382)
@@ -1799,7 +1799,7 @@ makectx(struct trapframe *tf, struct pcb
pcb->pcb_rbp = tf->tf_rbp;
pcb->pcb_rbx = tf->tf_rbx;
pcb->pcb_rip = tf->tf_rip;
- pcb->pcb_rsp = (ISPL(tf->tf_cs)) ? tf->tf_rsp : (long)(tf + 1) - 8;
+ pcb->pcb_rsp = tf->tf_rsp;
}
int
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