ref: 89c659d80b91170a20157119975b19492c33a1dd
parent: dd82b657c0a92a5e8f2d3df6c7ca3ae83403ce91
author: cinap_lenrek <cinap_lenrek@felloff.net>
date: Sun Nov 4 11:00:32 EST 2018
bcm: fix mysterious core clock resets under SMP (thanks richard miller)
reference: https://github.com/raspberrypi/firmware/issues/542
procsave(Proc* p)
{
uvlong t;
cycles(&t);
p->pcycles += t;
// TODO: save and restore VFPv3 FP state once 5[cal] know the new registers.
fpuprocsave(p);
/*
* Prevent the following scenario:
* pX sleeps on cpuA, leaving its page tables in mmul1
* pX wakes up on cpuB, and exits, freeing its page tables
* pY on cpuB allocates a freed page table page and overwrites with data
* cpuA takes an interrupt, and is now running with bad page tables
* In theory this shouldn't hurt because only user address space tables
* are affected, and mmuswitch will clear mmul1 before a user process is
* dispatched. But empirically it correlates with weird problems, eg
* resetting of the core clock at 0x4000001C which confuses local timers.
*/
if(conf.nmach > 1)
mmuswitch(nil);
}
--- a/sys/src/9/bcm/arch.c
+++ b/sys/src/9/bcm/arch.c
@@ -1,1 +1,203 @@
-#include "../omap/arch.c"
+#include "u.h"
+#include "../port/lib.h"
+#include "mem.h"
+#include "dat.h"
+#include "fns.h"
+#include "../port/error.h"
+
+#include <tos.h>
+#include "ureg.h"
+
+#include "arm.h"
+
+/*
+ * A lot of this stuff doesn't belong here
+ * but this is a convenient dumping ground for
+ * later sorting into the appropriate buckets.
+ */
+
+/* Give enough context in the ureg to produce a kernel stack for
+ * a sleeping process
+ */
+void
+setkernur(Ureg* ureg, Proc* p)
+{+ ureg->pc = p->sched.pc;
+ ureg->sp = p->sched.sp+4;
+ ureg->r14 = PTR2UINT(sched);
+}
+
+/*
+ * called in sysfile.c
+ */
+void
+evenaddr(uintptr addr)
+{+ if(addr & 3){+ postnote(up, 1, "sys: odd address", NDebug);
+ error(Ebadarg);
+ }
+}
+
+/* go to user space */
+void
+kexit(Ureg*)
+{+ uvlong t;
+ Tos *tos;
+
+ /* precise time accounting, kernel exit */
+ tos = (Tos*)(USTKTOP-sizeof(Tos));
+ cycles(&t);
+ tos->kcycles += t - up->kentry;
+ tos->pcycles = t + up->pcycles;
+ tos->cyclefreq = m->cpuhz;
+ tos->pid = up->pid;
+
+ /* make visible immediately to user proc */
+ cachedwbinvse(tos, sizeof *tos);
+}
+
+/*
+ * return the userpc the last exception happened at
+ */
+uintptr
+userpc(void)
+{+ Ureg *ureg = up->dbgreg;
+ return ureg->pc;
+}
+
+/* This routine must save the values of registers the user is not permitted
+ * to write from devproc and then restore the saved values before returning.
+ */
+void
+setregisters(Ureg* ureg, char* pureg, char* uva, int n)
+{+ USED(ureg, pureg, uva, n);
+}
+
+/*
+ * this is the body for all kproc's
+ */
+static void
+linkproc(void)
+{+ spllo();
+ up->kpfun(up->kparg);
+ pexit("kproc exiting", 0);+}
+
+/*
+ * setup stack and initial PC for a new kernel proc. This is architecture
+ * dependent because of the starting stack location
+ */
+void
+kprocchild(Proc *p, void (*func)(void*), void *arg)
+{+ p->sched.pc = PTR2UINT(linkproc);
+ p->sched.sp = PTR2UINT(p->kstack+KSTACK);
+
+ p->kpfun = func;
+ p->kparg = arg;
+}
+
+/*
+ * pc output by dumpaproc
+ */
+uintptr
+dbgpc(Proc* p)
+{+ Ureg *ureg;
+
+ ureg = p->dbgreg;
+ if(ureg == 0)
+ return 0;
+
+ return ureg->pc;
+}
+
+/*
+ * set mach dependent process state for a new process
+ */
+void
+procsetup(Proc* p)
+{+ fpusysprocsetup(p);
+
+ cycles(&p->kentry);
+ p->pcycles = -p->kentry;
+}
+
+void
+procfork(Proc* p)
+{+ p->kentry = up->kentry;
+ p->pcycles = -p->kentry;
+
+ fpuprocfork(p);
+}
+
+/*
+ * Save the mach dependent part of the process state.
+ */
+void
+procsave(Proc* p)
+{+ uvlong t;
+
+ cycles(&t);
+ p->pcycles += t;
+ p->kentry -= t;
+
+// TODO: save and restore VFPv3 FP state once 5[cal] know the new registers.
+ fpuprocsave(p);
+
+ /*
+ * Prevent the following scenario:
+ * pX sleeps on cpuA, leaving its page tables in mmul1
+ * pX wakes up on cpuB, and exits, freeing its page tables
+ * pY on cpuB allocates a freed page table page and overwrites with data
+ * cpuA takes an interrupt, and is now running with bad page tables
+ * In theory this shouldn't hurt because only user address space tables
+ * are affected, and mmuswitch will clear mmul1 before a user process is
+ * dispatched. But empirically it correlates with weird problems, eg
+ * resetting of the core clock at 0x4000001C which confuses local timers.
+ */
+ if(conf.nmach > 1)
+ mmuswitch(nil);
+}
+
+void
+procrestore(Proc* p)
+{+ uvlong t;
+
+ if(p->kp)
+ return;
+ cycles(&t);
+ p->pcycles -= t;
+ p->kentry += t;
+
+ fpuprocrestore(p);
+}
+
+int
+userureg(Ureg* ureg)
+{+ return (ureg->psr & PsrMask) == PsrMusr;
+}
+
+int
+cas32(void* addr, u32int old, u32int new)
+{+ int r, s;
+
+ s = splhi();
+ if(r = (*(u32int*)addr == old))
+ *(u32int*)addr = new;
+ splx(s);
+ if (r)
+ coherence();
+ return r;
+}