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noux: reduce stack usage

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By not placing the sysio buffer (16 KiB) on the stack, we can call
'noux_syscall' from the initial thread. This is needed to issue fork
from the suspend callback, which is executed by the initial thread.
This commit is contained in:
Norman Feske 2016-12-06 15:32:17 +01:00
parent 10ba9c8f20
commit 4475ac10d6
1 changed files with 11 additions and 2 deletions
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13
repos/ports/src/lib/libc_noux/plugin.cc
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@ -156,14 +156,22 @@ static bool noux_syscall(Noux::Session::Syscall opcode)
{ {
/* /*
* Signal handlers might do syscalls themselves, so the 'sysio' object * Signal handlers might do syscalls themselves, so the 'sysio' object
* needs to get saved before and restored after calling the signal handler. * needs to be saved before and restored after calling the signal handler.
* There is only one global 'saved_sysio' buffer as signals are not checked
* in nested calls of 'noux_syscall' from signal handlers.
*/ */
Noux::Sysio saved_sysio; static Noux::Sysio saved_sysio;
bool ret = noux()->syscall(opcode); bool ret = noux()->syscall(opcode);
static bool in_sigh = false; /* true if called from signal handler */
if (in_sigh)
return ret;
/* handle signals */ /* handle signals */
while (!sysio()->pending_signals.empty()) { while (!sysio()->pending_signals.empty()) {
in_sigh = true;
Noux::Sysio::Signal signal = sysio()->pending_signals.get(); Noux::Sysio::Signal signal = sysio()->pending_signals.get();
if (verbose_signals) if (verbose_signals)
log(__func__, ": received signal ", (int)signal); log(__func__, ": received signal ", (int)signal);
@ -191,6 +199,7 @@ static bool noux_syscall(Noux::Session::Syscall opcode)
} }
} }
} }
in_sigh = false;
return ret; return ret;
} }