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<p class=MsoNormal><font size=1 face=Arial><span lang=EN-US style='font-size:
9.0pt;font-family:Arial'>Hi Dave,<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=1 face=Arial><span lang=EN-US style='font-size:
9.0pt;font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=1 face=Arial><span lang=EN-US style='font-size:
9.0pt;font-family:Arial'>Current I am trying to make crash support display out
function param and local value while backtracing.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=1 face=Arial><span lang=EN-US style='font-size:
9.0pt;font-family:Arial'>The idea for this patch is to mimic core dump support
in gdb, teaching the crash to supply the regset to the gdb, so that gdb could
have full knowledge what is going on in the panic point.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=1 face=Arial><span lang=EN-US style='font-size:
9.0pt;font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=1 face=Arial><span lang=EN-US style='font-size:
9.0pt;font-family:Arial'>A few progress has been made, the first two frames
could display out correctly, but while it is going on to display out the third
frame, it report fail as “Cannot access memory” to the stack address.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=1 face=Arial><span lang=EN-US style='font-size:
9.0pt;font-family:Arial'>While I use the rd command to access this range, and
could correct pc value there.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=1 face=Arial><span lang=EN-US style='font-size:
9.0pt;font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=1 face=Arial><span lang=EN-US style='font-size:
9.0pt;font-family:Arial'>With further check, I find it failed at value_fetch_lazy
at gdb code.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=1 face=Arial><span lang=EN-US style='font-size:
9.0pt;font-family:Arial'>Do you have any idea why gdb side couldn’t read the
stack content?<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=1 face=Arial><span lang=EN-US style='font-size:
9.0pt;font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=1 face=Arial><span lang=EN-US style='font-size:
9.0pt;font-family:Arial'>The generated log as: <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=1 face=Arial><span lang=EN-US style='font-size:
9.0pt;font-family:Arial'>crash> bt<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=1 face=Arial><span lang=EN-US style='font-size:
9.0pt;font-family:Arial'>PID: 886 TASK: c<st1:chmetcnv TCSC="0"
NumberType="1" Negative="False" HasSpace="False" SourceValue="54991"
UnitName="a" w:st="on">54991a</st1:chmetcnv>0 CPU: 0 COMMAND: "sh"<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=1 face=Arial><span lang=EN-US style='font-size:
9.0pt;font-family:Arial'>#0 sysrq_handle_crash (key=99) at drivers/tty/sysrq.c:132<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=1 face=Arial><span lang=EN-US style='font-size:
9.0pt;font-family:Arial'>No locals.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=1 face=Arial><span lang=EN-US style='font-size:
9.0pt;font-family:Arial'>#1 0xc02da6dc in __handle_sysrq (key=99, check_mask=false)
at drivers/tty/sysrq.c:522<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=1 face=Arial><span lang=EN-US style='font-size:
9.0pt;font-family:Arial'> op_p = 0xc06dbeb8<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=1 face=Arial><span lang=EN-US style='font-size:
9.0pt;font-family:Arial'> orig_log_level = 7<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=1 face=Arial><span lang=EN-US style='font-size:
9.0pt;font-family:Arial'> i = -1066549576<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=1 face=Arial><span lang=EN-US style='font-size:
9.0pt;font-family:Arial'> flags = 1610612755<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=1 face=Arial><span lang=EN-US style='font-size:
9.0pt;font-family:Arial'>Cannot access memory at address 0xd29d<st1:chmetcnv
TCSC="0" NumberType="1" Negative="False" HasSpace="False" SourceValue="5"
UnitName="F" w:st="on">5f</st1:chmetcnv>34<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=1 face=Arial><span lang=EN-US style='font-size:
9.0pt;font-family:Arial'>bt: display local fail at c02da<st1:chmetcnv TCSC="0"
NumberType="1" Negative="False" HasSpace="False" SourceValue="1" UnitName="C"
w:st="on">1c</st1:chmetcnv>0<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=1 face=Arial><span lang=EN-US style='font-size:
9.0pt;font-family:Arial'>crash> rd 0xd29d<st1:chmetcnv TCSC="0"
NumberType="1" Negative="False" HasSpace="False" SourceValue="5" UnitName="F"
w:st="on">5f</st1:chmetcnv>34 1<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=1 face=Arial><span lang=EN-US style='font-size:
9.0pt;font-family:Arial'>d29d<st1:chmetcnv TCSC="0" NumberType="1"
Negative="False" HasSpace="False" SourceValue="5" UnitName="F" w:st="on">5f</st1:chmetcnv>34:
c02da7cc ..-.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=1 face=Arial><span lang=EN-US style='font-size:
9.0pt;font-family:Arial'>crash> sym c02da7cc<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=1 face=Arial><span lang=EN-US style='font-size:
9.0pt;font-family:Arial'>c02da7cc (t) write_sysrq_trigger+40 /kernel/drivers/tty/sysrq.c:
873<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=1 face=Arial><span lang=EN-US style='font-size:
9.0pt;font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=1 face=Arial><span lang=EN-US style='font-size:
9.0pt;font-family:Arial'>Thanks,<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=1 face=Arial><span lang=EN-US style='font-size:
9.0pt;font-family:Arial'>Lei<o:p></o:p></span></font></p>
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