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The makectx() function, used by kdb_trap() to reconstruct pcb from

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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
This commit is contained in:
Konstantin Belousov 2010-10-03 13:52:17 +00:00
parent 832f8c8a9b
commit 2d5db3709b
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=213382
1 changed files with 1 additions and 1 deletions
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2
sys/amd64/amd64/machdep.c
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@ -1799,7 +1799,7 @@ makectx(struct trapframe *tf, struct pcb *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