Al Viro <viro@xxxxxxxxxxxxxxxxxx> writes:
On Thu, Sep 30, 2010 at 10:21:47AM +0200, Andreas Schwab wrote:
Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> writes:
So what's that SIGTRAP on exit from syscall in single-stepping mode for?
The trace exception is low priority exception that is executed after all
other exceptions are processed. So if the cpu single steps over a trap
insns, the trace exception processing is started when the trap exception
processing is complete, which is just before the cpu starts executing
the trap exception handler in the kernel. You want the SIGTRAP to be
sent to the user process, so you have to delay sending it until the
kernel returns to user space.
Um... What's wrong with doing that from trap_c()?
IIRC that was the only way to make gdb work correctly wrt. single
stepping over system calls and into signal handlers. If anyone wants to
test it with today's kernel on real hardware, please go ahead.
Andreas.
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Andreas Schwab, schwab@xxxxxxxxxxxxxx
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