kib e68de2436e 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
2010-10-03 13:52:17 +00:00
..
2010-08-19 16:41:27 +00:00