[SPARC64]: Fix booting on non-zero cpu.

The early per-cpu handling needs a slight tweak to work when booting on a non-zero cpu. We got away with this for a long time, but can't any longer as now even printk() calls functions (cpu_clock() for example) that thus make early references to per-cpu variables. Signed-off-by: David S. Miller <davem@davemloft.net>

[SPARC64]: Fix booting on non-zero cpu.
The early per-cpu handling needs a slight tweak to work when booting on a non-zero cpu. We got away with this for a long time, but can't any longer as now even printk() calls functions (cpu_clock() for example) that thus make early references to per-cpu variables. Signed-off-by: David S. Miller <davem@davemloft.net>
David S. Miller
1 parent 488b5ec871
Showing 2 changed files with 28 additions and 0 deletions Side-by-side Diff
arch/sparc64/kernel/head.S
arch/sparc64/prom/init.c
@@ -632,10 +632,35 @@
 	/* Not reached... */
  
 1:
+	/* If we boot on a non-zero cpu, all of the per-cpu
+	 * variable references we make before setting up the
+	 * per-cpu areas will use a bogus offset.  Put a
+	 * compensating factor into __per_cpu_base to handle
+	 * this cleanly.
+	 *
+	 * What the per-cpu code calculates is:
+	 *
+	 *	__per_cpu_base + (cpu << __per_cpu_shift)
+	 *
+	 * These two variables are zero initially, so to
+	 * make it all cancel out to zero we need to put
+	 * "0 - (cpu << 0)" into __per_cpu_base so that the
+	 * above formula evaluates to zero.
+	 *
+	 * We cannot even perform a printk() until this stuff
+	 * is setup as that calls cpu_clock() which uses
+	 * per-cpu variables.
+	 */
+	sub	%g0, %o0, %o1
+	sethi	%hi(__per_cpu_base), %o2
+	stx	%o1, [%o2 + %lo(__per_cpu_base)]
 #else
 	mov	0, %o0
 #endif
 	sth	%o0, [%g6 + TI_CPU]
+
+	call	prom_init_report
+	 nop
  
 	/* Off we go.... */
 	call	start_kernel
@@ -48,7 +48,10 @@
 	prom_getstring(node, "version", prom_version, sizeof(prom_version));
  
 	prom_printf("\n");
+}
  
+void __init prom_init_report(void)
+{
 	printk("PROMLIB: Sun IEEE Boot Prom '%s'\n", prom_version);
 	printk("PROMLIB: Root node compatible: %s\n", prom_root_compatible);
 }
...	...	@@ -632,10 +632,35 @@
632	632	/* Not reached... */
633	633
634	634	1:
	635	+ /* If we boot on a non-zero cpu, all of the per-cpu
	636	+ * variable references we make before setting up the
	637	+ * per-cpu areas will use a bogus offset. Put a
	638	+ * compensating factor into __per_cpu_base to handle
	639	+ * this cleanly.
	640	+ *
	641	+ * What the per-cpu code calculates is:
	642	+ *
	643	+ * __per_cpu_base + (cpu << __per_cpu_shift)
	644	+ *
	645	+ * These two variables are zero initially, so to
	646	+ * make it all cancel out to zero we need to put
	647	+ * "0 - (cpu << 0)" into __per_cpu_base so that the
	648	+ * above formula evaluates to zero.
	649	+ *
	650	+ * We cannot even perform a printk() until this stuff
	651	+ * is setup as that calls cpu_clock() which uses
	652	+ * per-cpu variables.
	653	+ */
	654	+ sub %g0, %o0, %o1
	655	+ sethi %hi(__per_cpu_base), %o2
	656	+ stx %o1, [%o2 + %lo(__per_cpu_base)]
635	657	#else
636	658	mov 0, %o0
637	659	#endif
638	660	sth %o0, [%g6 + TI_CPU]
	661	+
	662	+ call prom_init_report
	663	+ nop
639	664
640	665	/* Off we go.... */
641	666	call start_kernel
...	...	@@ -48,7 +48,10 @@
48	48	prom_getstring(node, "version", prom_version, sizeof(prom_version));
49	49
50	50	prom_printf("\n");
	51	+}
51	52
	53	+void __init prom_init_report(void)
	54	+{
52	55	printk("PROMLIB: Sun IEEE Boot Prom '%s'\n", prom_version);
53	56	printk("PROMLIB: Root node compatible: %s\n", prom_root_compatible);
54	57	}