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authorKyösti Mälkki <kyosti.malkki@gmail.com>2012-03-04 02:24:36 +0200
committerRudolf Marek <r.marek@assembler.cz>2012-03-25 20:35:26 +0200
commita01ae624af5a9afa0e8799aa0f8823d6b8137457 (patch)
treeb5b3e2a69fb5c425a7180261ff6cfaacce91c107 /src/cpu/x86/lapic
parent8b28d50cdd1384893ec0565453eea77031aa7ec8 (diff)
downloadcoreboot-a01ae624af5a9afa0e8799aa0f8823d6b8137457.tar.xz
Fix possible deadlock on SMP stop_this_cpu
Do not use printk on the running thread after it has been sent the INIT IPI, execution may halt with console spinlock held. Change-Id: I64608935ea740fb827fa0307442f3fb102de7a08 Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com> Reviewed-on: http://review.coreboot.org/776 Reviewed-by: Ronald G. Minnich <rminnich@gmail.com> Tested-by: build bot (Jenkins) Reviewed-by: Rudolf Marek <r.marek@assembler.cz>
Diffstat (limited to 'src/cpu/x86/lapic')
-rw-r--r--src/cpu/x86/lapic/lapic_cpu_init.c29
1 files changed, 25 insertions, 4 deletions
diff --git a/src/cpu/x86/lapic/lapic_cpu_init.c b/src/cpu/x86/lapic/lapic_cpu_init.c
index fc22ea4adf..2e2bb0632c 100644
--- a/src/cpu/x86/lapic/lapic_cpu_init.c
+++ b/src/cpu/x86/lapic/lapic_cpu_init.c
@@ -277,6 +277,19 @@ int start_cpu(device_t cpu)
}
#if CONFIG_AP_IN_SIPI_WAIT == 1
+
+/**
+ * Sending INIT IPI to self is equivalent of asserting #INIT with a bit of delay.
+ * An undefined number of instruction cycles will complete. All global locks
+ * must be released before INIT IPI and no printk is allowed after this.
+ * De-asserting INIT IPI is a no-op on later Intel CPUs.
+ *
+ * If you set DEBUG_HALT_SELF to 1, printk's after INIT IPI are enabled
+ * but running thread may halt without releasing the lock and effectively
+ * deadlock other CPUs.
+ */
+#define DEBUG_HALT_SELF 0
+
/**
* Normally this function is defined in lapic.h as an always inline function
* that just keeps the CPU in a hlt() loop. This does not work on all CPUs.
@@ -298,38 +311,46 @@ void stop_this_cpu(void)
lapic_write_around(LAPIC_ICR, LAPIC_INT_LEVELTRIG | LAPIC_INT_ASSERT | LAPIC_DM_INIT);
/* wait for the ipi send to finish */
-#if 0
- // When these two printk(BIOS_SPEW, ...) calls are not removed, the
- // machine will hang when log level is SPEW. Why?
+#if DEBUG_HALT_SELF
printk(BIOS_SPEW, "Waiting for send to finish...\n");
#endif
timeout = 0;
do {
-#if 0
+#if DEBUG_HALT_SELF
printk(BIOS_SPEW, "+");
#endif
udelay(100);
send_status = lapic_read(LAPIC_ICR) & LAPIC_ICR_BUSY;
} while (send_status && (timeout++ < 1000));
if (timeout >= 1000) {
+#if DEBUG_HALT_SELF
printk(BIOS_ERR, "timed out\n");
+#endif
}
mdelay(10);
+#if DEBUG_HALT_SELF
printk(BIOS_SPEW, "Deasserting INIT.\n");
+#endif
/* Deassert the LAPIC INIT */
lapic_write_around(LAPIC_ICR2, SET_LAPIC_DEST_FIELD(id));
lapic_write_around(LAPIC_ICR, LAPIC_INT_LEVELTRIG | LAPIC_DM_INIT);
+#if DEBUG_HALT_SELF
printk(BIOS_SPEW, "Waiting for send to finish...\n");
+#endif
timeout = 0;
do {
+#if DEBUG_HALT_SELF
printk(BIOS_SPEW, "+");
+#endif
udelay(100);
send_status = lapic_read(LAPIC_ICR) & LAPIC_ICR_BUSY;
} while (send_status && (timeout++ < 1000));
if (timeout >= 1000) {
+#if DEBUG_HALT_SELF
printk(BIOS_ERR, "timed out\n");
+#endif
}
while(1) {