Module Name: src
Committed By: dyoung
Date: Tue Apr 27 23:33:14 UTC 2010
Modified Files:
src/sys/arch/x86/pci: pci_machdep.c
Log Message:
Make pci_conf_read(9) and pci_conf_write(9) re-entrant so that the
kernel can use them in an NMI trap handler. Only one CPU can be
in _read() or _write() at once. However, on any single CPU, more
than one thread of execution (LWP, interrupt handler, trap handler)
may be in _read() or _write() at once, because each thread saves
and restores the PCI configuration-access state.
To generate a diff of this commit:
cvs rdiff -u -r1.41 -r1.42 src/sys/arch/x86/pci/pci_machdep.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/arch/x86/pci/pci_machdep.c
diff -u src/sys/arch/x86/pci/pci_machdep.c:1.41 src/sys/arch/x86/pci/pci_machdep.c:1.42
--- src/sys/arch/x86/pci/pci_machdep.c:1.41 Sun Mar 14 20:19:06 2010
+++ src/sys/arch/x86/pci/pci_machdep.c Tue Apr 27 23:33:14 2010
@@ -1,4 +1,4 @@
-/* $NetBSD: pci_machdep.c,v 1.41 2010/03/14 20:19:06 dyoung Exp $ */
+/* $NetBSD: pci_machdep.c,v 1.42 2010/04/27 23:33:14 dyoung Exp $ */
/*-
* Copyright (c) 1997, 1998 The NetBSD Foundation, Inc.
@@ -73,7 +73,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: pci_machdep.c,v 1.41 2010/03/14 20:19:06 dyoung Exp $");
+__KERNEL_RCSID(0, "$NetBSD: pci_machdep.c,v 1.42 2010/04/27 23:33:14 dyoung Exp $");
#include <sys/types.h>
#include <sys/param.h>
@@ -82,6 +82,7 @@
#include <sys/errno.h>
#include <sys/device.h>
#include <sys/bus.h>
+#include <sys/cpu.h>
#include <uvm/uvm_extern.h>
@@ -129,26 +130,24 @@
static int pci_mode = -1;
#endif
+struct pci_conf_lock {
+ uint32_t cl_cpuno; /* 0: unlocked
+ * 1 + n: locked by CPU n (0 <= n)
+ */
+ uint32_t cl_sel; /* the address that's being read. */
+};
+
+static void pci_conf_unlock(struct pci_conf_lock *);
+static uint32_t pci_conf_selector(pcitag_t, int);
+static unsigned int pci_conf_port(pcitag_t, int);
+static void pci_conf_select(uint32_t);
+static void pci_conf_lock(struct pci_conf_lock *, uint32_t);
static void pci_bridge_hook(pci_chipset_tag_t, pcitag_t, void *);
struct pci_bridge_hook_arg {
void (*func)(pci_chipset_tag_t, pcitag_t, void *);
void *arg;
};
-__cpu_simple_lock_t pci_conf_lock = __SIMPLELOCK_UNLOCKED;
-
-#define PCI_CONF_LOCK(s) \
-do { \
- (s) = splhigh(); \
- __cpu_simple_lock(&pci_conf_lock); \
-} while (0)
-
-#define PCI_CONF_UNLOCK(s) \
-do { \
- __cpu_simple_unlock(&pci_conf_lock); \
- splx((s)); \
-} while (0)
-
#define PCI_MODE1_ENABLE 0x80000000UL
#define PCI_MODE1_ADDRESS_REG 0x0cf8
#define PCI_MODE1_DATA_REG 0x0cfc
@@ -243,6 +242,63 @@
};
#endif
+static struct pci_conf_lock cl0 = {
+ .cl_cpuno = 0UL
+ , .cl_sel = 0UL
+};
+
+static struct pci_conf_lock * const cl = &cl0;
+
+static void
+pci_conf_lock(struct pci_conf_lock *ocl, uint32_t sel)
+{
+ uint32_t cpuno;
+
+ KASSERT(sel != 0);
+
+ kpreempt_disable();
+ cpuno = cpu_number() + 1;
+ /* If the kernel enters pci_conf_lock() through an interrupt
+ * handler, then the CPU may already hold the lock.
+ *
+ * If the CPU does not already hold the lock, spin until
+ * we can acquire it.
+ */
+ if (cpuno == cl->cl_cpuno) {
+ ocl->cl_cpuno = cpuno;
+ } else {
+ ocl->cl_cpuno = 0;
+ while (atomic_cas_32(&cl->cl_cpuno, 0, cpuno) != 0)
+ ;
+ }
+
+ /* Only one CPU can be here, so an interlocked atomic_swap(3)
+ * is not necessary.
+ *
+ * Evaluating atomic_cas_32_ni()'s argument, cl->cl_sel,
+ * and applying atomic_cas_32_ni() is not an atomic operation,
+ * however, any interrupt that, in the middle of the
+ * operation, modifies cl->cl_sel, will also restore
+ * cl->cl_sel. So cl->cl_sel will have the same value when
+ * we apply atomic_cas_32_ni() as when we evaluated it,
+ * before.
+ */
+ ocl->cl_sel = atomic_cas_32_ni(&cl->cl_sel, cl->cl_sel, sel);
+ pci_conf_select(sel);
+}
+
+static void
+pci_conf_unlock(struct pci_conf_lock *ocl)
+{
+ uint32_t sel;
+
+ sel = atomic_cas_32_ni(&cl->cl_sel, cl->cl_sel, ocl->cl_sel);
+ pci_conf_select(ocl->cl_sel);
+ if (ocl->cl_cpuno != cl->cl_cpuno)
+ atomic_cas_32(&cl->cl_cpuno, cl->cl_cpuno, ocl->cl_cpuno);
+ kpreempt_enable();
+}
+
static uint32_t
pci_conf_selector(pcitag_t tag, int reg)
{
@@ -277,16 +333,16 @@
}
static void
-pci_conf_select(uint32_t addr)
+pci_conf_select(uint32_t sel)
{
pcitag_t tag;
switch (pci_mode) {
case 1:
- outl(PCI_MODE1_ADDRESS_REG, addr);
+ outl(PCI_MODE1_ADDRESS_REG, sel);
return;
case 2:
- tag.mode1 = addr;
+ tag.mode1 = sel;
outb(PCI_MODE2_ENABLE_REG, tag.mode2.enable);
if (tag.mode2.enable != 0)
outb(PCI_MODE2_FORWARD_REG, tag.mode2.forward);
@@ -417,7 +473,7 @@
int reg)
{
pcireg_t data;
- int s;
+ struct pci_conf_lock ocl;
KASSERT((reg & 0x3) == 0);
@@ -437,11 +493,9 @@
}
#endif
- PCI_CONF_LOCK(s);
- pci_conf_select(pci_conf_selector(tag, reg));
+ pci_conf_lock(&ocl, pci_conf_selector(tag, reg));
data = inl(pci_conf_port(tag, reg));
- pci_conf_select(0);
- PCI_CONF_UNLOCK(s);
+ pci_conf_unlock(&ocl);
return data;
}
@@ -449,7 +503,7 @@
pci_conf_write(pci_chipset_tag_t pc, pcitag_t tag, int reg,
pcireg_t data)
{
- int s;
+ struct pci_conf_lock ocl;
KASSERT((reg & 0x3) == 0);
@@ -473,11 +527,9 @@
}
#endif
- PCI_CONF_LOCK(s);
- pci_conf_select(pci_conf_selector(tag, reg));
+ pci_conf_lock(&ocl, pci_conf_selector(tag, reg));
outl(pci_conf_port(tag, reg), data);
- pci_conf_select(0);
- PCI_CONF_UNLOCK(s);
+ pci_conf_unlock(&ocl);
}
void
