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Make RTAS calls, which call setfault() to recover from machine checks,

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preserve any existing fault buffer. RTAS calls are meant to be safe from
interrupt context (and are indeed used there to implement the xics PIC
drvier). Without this, calling into RTAS in interrupt context would have
the effect of clearing any existing onfault state of the interrupted
thread, potentially leading to a panic.
This commit is contained in:
Nathan Whitehorn 2013-11-27 21:51:34 +00:00
parent cec48e002a
commit 1679c30254
1 changed files with 3 additions and 2 deletions
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5
sys/powerpc/ofw/rtas.c
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@ -192,7 +192,7 @@ int
rtas_call_method(cell_t token, int nargs, int nreturns, ...)
{
vm_offset_t argsptr;
faultbuf env;
faultbuf env, *oldfaultbuf;
va_list ap;
struct {
cell_t token;
@ -221,6 +221,7 @@ rtas_call_method(cell_t token, int nargs, int nreturns, ...)
/* Get rid of any stale machine checks that have been waiting. */
__asm __volatile ("sync; isync");
oldfaultbuf = curthread->td_pcb->pcb_onfault;
if (!setfault(env)) {
__asm __volatile ("sync");
result = rtascall(argsptr, rtas_private_data);
@ -228,7 +229,7 @@ rtas_call_method(cell_t token, int nargs, int nreturns, ...)
} else {
result = RTAS_HW_ERROR;
}
curthread->td_pcb->pcb_onfault = 0;
curthread->td_pcb->pcb_onfault = oldfaultbuf;
__asm __volatile ("sync");
rtas_real_unmap(argsptr, &args, sizeof(args));