Re: [Patch] Per CPU MCA/INIT data save areas

[Takao Indoh <indou.takao@soft.fujitsu.com>]

Hi,

On Tue, 31 Aug 2004 16:12:25 -0500 (CDT), Russ Anderson wrote:

>
>This is a patch to create per cpu MCA/INIT data save areas.
>
>Signed-off-by: Russ Anderson <rja@sgi.com>
>
>High level description:
>
>  Linux currently has one MCA & INIT save area for saving
>  stack and other data.  This patch creates per cpu MCA/INIT 
>  save areas, so that each cpu can save its own MCA & INIT stack 
>  data.
>
>  The per MCA/INIT save areas replace the global areas defined
>  in arch/ia64/kernel/mca.c for MCA processor state dump, 
>  MCA stack, MCA stack frame, INIT stack, and MCA bspstore.
>
>  The code to access those save areas is updated to use the
>  per cpu save areas.
>
>  No changes are made to the MCA flow, ie all the old locks
>  are still in place.  The point of this patch is to establish
>  the per cpu save areas.  Additional usage of the save areas,
>  such as enabling concurrent INIT or MCA handling, will be
>  the subject of other patches.
>


I am interested in INIT stack improvement and tried your patch, but
it didn't work. I reviewed the patch and found some bugs. After I fixed
them, your patch seemed to work correctly.
I corrected the following two parts.

1) MINSTATE_START_SAVE_MIN_PHYS

THIS_CPU(cpu_info) is insufficient. We need to find appropriate
address of cpu_info structure for each cpu using thread_info->cpu
and __per_cpu_offset like this:

	THIS_CPU(cpu_info) + __per_cpu_offset[cpu];

BTW, I used tpa to get physical address, but I am not sure TLB is valid 
in the OS_INIT. tpa is available?


2) find_pernode_space()

cpu_data points the address of the top of per_cpu area, not cpuinfo_ia64
structure. Therefore,

	cpuinfo = (struct cpuinfo_ia64 *)cpu_data;

This has to be fixed as follows.

	cpuinfo = (struct cpuinfo_ia64 *)(__va(cpu_data) +
	    ((char *)&per_cpu__cpu_info - __per_cpu_start));

In your patch, ia64_mca_data is set if ((cpu = 0) ||
(node_cpuid[cpu].phys_id > 0)) is true.
I don't know what "node_cpuid[cpu].phys_id" is, but I found that it is
initialized at acpi_boot_init(). find_pernode_space() is called earlier
than acpi_boot_init(), so this condition always returns false except
cpu0. Therefore, I remove this condition. (But this may be dependent on kernel
configuration.)

This is a patch I updated. I reviewed only the INIT code, so there may be
some bugs in MCA code.

Best Regards,
Takao Indoh


diff -Nur linux-2.6.8.1.org/arch/ia64/kernel/asm-offsets.c linux-2.6.8.1/arch/ia64/kernel/asm-offsets.c
--- linux-2.6.8.1.org/arch/ia64/kernel/asm-offsets.c	2004-09-14 15:15:40.878796742 +0900
+++ linux-2.6.8.1/arch/ia64/kernel/asm-offsets.c	2004-09-13 16:29:04.000000000 +0900
@@ -45,6 +45,7 @@
 	DEFINE(IA64_TASK_TGID_OFFSET, offsetof (struct task_struct, tgid));
 	DEFINE(IA64_TASK_THREAD_KSP_OFFSET, offsetof (struct task_struct, thread.ksp));
 	DEFINE(IA64_TASK_THREAD_ON_USTACK_OFFSET, offsetof (struct task_struct, thread.on_ustack));
+	DEFINE(IA64_THREAD_INFO_CPU_OFFSET, offsetof (struct thread_info, cpu));
 
 	BLANK();
 
@@ -194,6 +195,13 @@
 	DEFINE(IA64_CPUINFO_NSEC_PER_CYC_OFFSET, offsetof (struct cpuinfo_ia64, nsec_per_cyc));
 	DEFINE(IA64_TIMESPEC_TV_NSEC_OFFSET, offsetof (struct timespec, tv_nsec));
 
+    /* used by arch/ia64/kernel/mca_asm.S */
+	DEFINE(IA64_CPUINFO_MCA_DATA, offsetof (struct cpuinfo_ia64, ia64_mca_data));
+	DEFINE(IA64_MCA_PROC_STATE_DUMP, offsetof (struct ia64_mca_cpu_s, ia64_mca_proc_state_dump));
+	DEFINE(IA64_MCA_STACK, offsetof (struct ia64_mca_cpu_s, ia64_mca_stack));
+	DEFINE(IA64_MCA_STACKFRAME, offsetof (struct ia64_mca_cpu_s, ia64_mca_stackframe));
+	DEFINE(IA64_MCA_BSPSTORE, offsetof (struct ia64_mca_cpu_s, ia64_mca_bspstore));
+	DEFINE(IA64_INIT_STACK, offsetof (struct ia64_mca_cpu_s, ia64_init_stack));
 
 	DEFINE(CLONE_IDLETASK_BIT, 12);
 #if CLONE_IDLETASK != (1 << 12)
diff -Nur linux-2.6.8.1.org/arch/ia64/kernel/mca.c linux-2.6.8.1/arch/ia64/kernel/mca.c
--- linux-2.6.8.1.org/arch/ia64/kernel/mca.c	2004-09-14 15:15:40.875867055 +0900
+++ linux-2.6.8.1/arch/ia64/kernel/mca.c	2004-09-14 14:50:29.537018381 +0900
@@ -3,6 +3,9 @@
  * Purpose:	Generic MCA handling layer
  *
  * Updated for latest kernel
+ * Copyright (C) 2004 Silicon Graphics, Inc
+ *	Russ Anderson <rja@sgi.com>
+ *
  * Copyright (C) 2003 Hewlett-Packard Co
  *	David Mosberger-Tang <davidm@hpl.hp.com>
  *
@@ -90,11 +93,6 @@
 /* Used by mca_asm.S */
 ia64_mca_sal_to_os_state_t	ia64_sal_to_os_handoff_state;
 ia64_mca_os_to_sal_state_t	ia64_os_to_sal_handoff_state;
-u64				ia64_mca_proc_state_dump[512];
-u64				ia64_mca_stack[1024] __attribute__((aligned(16)));
-u64				ia64_mca_stackframe[32];
-u64				ia64_mca_bspstore[1024];
-u64				ia64_init_stack[KERNEL_STACK_SIZE/8] __attribute__((aligned(16)));
 u64				ia64_mca_serialize;
 
 /* In mca_asm.S */
diff -Nur linux-2.6.8.1.org/arch/ia64/kernel/mca_asm.S linux-2.6.8.1/arch/ia64/kernel/mca_asm.S
--- linux-2.6.8.1.org/arch/ia64/kernel/mca_asm.S	2004-09-14 15:15:40.877820180 +0900
+++ linux-2.6.8.1/arch/ia64/kernel/mca_asm.S	2004-09-13 14:08:18.000000000 +0900
@@ -1,6 +1,9 @@
 //
 // assembly portion of the IA64 MCA handling
 //
+// 04/08/27 Russ Anderson <rja@sgi.com>
+//		   Added per cpu MCA/INIT stack save areas.
+//
 // Mods by cfleck to integrate into kernel build
 // 00/03/15 davidm Added various stop bits to get a clean compile
 //
@@ -102,11 +105,6 @@
 	.global ia64_os_mca_dispatch_end
 	.global ia64_sal_to_os_handoff_state
 	.global	ia64_os_to_sal_handoff_state
-	.global	ia64_mca_proc_state_dump
-	.global	ia64_mca_stack
-	.global	ia64_mca_stackframe
-	.global	ia64_mca_bspstore
-	.global ia64_init_stack
 
 	.text
 	.align 16
@@ -318,17 +316,17 @@
 done_tlb_purge_and_reload:
 
 	// Setup new stack frame for OS_MCA handling
-	movl	r2=ia64_mca_bspstore;;	// local bspstore area location in r2
-	DATA_VA_TO_PA(r2);;
-	movl	r3=ia64_mca_stackframe;; // save stack frame to memory in r3
-	DATA_VA_TO_PA(r3);;
+	addl	r2 = THIS_CPU(cpu_info) + IA64_CPUINFO_MCA_DATA,r0;;
+	ld8	r2=[r2];;	// r2 pointing to top of this cpu's MCA/INIT save area
+	addl	r3 = IA64_MCA_STACKFRAME, r2
+	addl	r12 = IA64_MCA_STACK, r2
+	addl	r2 = IA64_MCA_BSPSTORE, r2;;
+
 	rse_switch_context(r6,r3,r2);;	// RSC management in this new context
-	movl	r12=ia64_mca_stack
 	mov	r2=8*1024;;		// stack size must be same as C array
 	add	r12=r2,r12;;		// stack base @ bottom of array
 	adds	r12=-16,r12;;		// allow 16 bytes of scratch
 					// (C calling convention)
-	DATA_VA_TO_PA(r12);;
 
         // Enter virtual mode from physical mode
 	VIRTUAL_MODE_ENTER(r2, r3, ia64_os_mca_virtual_begin, r4)
@@ -344,9 +342,9 @@
 ia64_os_mca_virtual_end:
 
 	// restore the original stack frame here
-	movl    r2=ia64_mca_stackframe	// restore stack frame from memory at r2
-	;;
-	DATA_VA_TO_PA(r2)
+	addl	r2 = THIS_CPU(cpu_info) + IA64_CPUINFO_MCA_DATA,r0;;
+	ld8	r2=[r2];;	// r2 pointing to top of this cpu's MCA/INIT save area
+	addl	r2 = IA64_MCA_STACKFRAME, r2;;
 	movl    r4=IA64_PSR_MC
 	;;
 	rse_return_context(r4,r3,r2)	// switch from interrupt context for RSE
@@ -387,8 +385,10 @@
 ia64_os_mca_proc_state_dump:
 // Save bank 1 GRs 16-31 which will be used by c-language code when we switch
 //  to virtual addressing mode.
-	LOAD_PHYSICAL(p0,r2,ia64_mca_proc_state_dump)// convert OS state dump area to physical address
-
+	addl		r2 = THIS_CPU(cpu_info) + IA64_CPUINFO_MCA_DATA,r0;;
+	ld8		r2=[r2];;	// r2 pointing to top of this cpu's MCA/INIT save area
+	addl		r2 = IA64_MCA_PROC_STATE_DUMP, r2;;
+					// r2 now points at ia64_mca_proc_state_dump area
 // save ar.NaT
 	mov		r5=ar.unat                  // ar.unat
 
@@ -618,9 +618,10 @@
 ia64_os_mca_proc_state_restore:
 
 // Restore bank1 GR16-31
-	movl		r2=ia64_mca_proc_state_dump	// Convert virtual address
-	;;						// of OS state dump area
-	DATA_VA_TO_PA(r2)				// to physical address
+	addl		r2=THIS_CPU(cpu_info) + IA64_CPUINFO_MCA_DATA, r0;;
+	ld8		r2=[r2];;	// r2 pointing to top of this cpu's MCA/INIT save area
+	addl		r2 = IA64_MCA_PROC_STATE_DUMP, r2;;
+					// r2 now points at ia64_mca_proc_state_dump area
 
 restore_GRs:                                    // restore bank-1 GRs 16-31
 	bsw.1;;
diff -Nur linux-2.6.8.1.org/arch/ia64/kernel/minstate.h linux-2.6.8.1/arch/ia64/kernel/minstate.h
--- linux-2.6.8.1.org/arch/ia64/kernel/minstate.h	2004-09-14 15:15:40.876843617 +0900
+++ linux-2.6.8.1/arch/ia64/kernel/minstate.h	2004-09-14 15:14:39.406141245 +0900
@@ -37,7 +37,18 @@
  * go virtual and don't want to destroy the iip or ipsr.
  */
 #define MINSTATE_START_SAVE_MIN_PHYS								\
-(pKStk) movl sp=ia64_init_stack+IA64_STK_OFFSET-IA64_PT_REGS_SIZE;				\
+(pKStk) adds r16=IA64_TASK_SIZE+IA64_THREAD_INFO_CPU_OFFSET,r1;;	/* thread_info->cpu */	\
+(pKStk) ld4 r16=[r16];				/* smp_processor_id */				\
+(pKStk) movl r2=__per_cpu_offset;;								\
+(pKStk) shladd r2=r16,3,r2;;									\
+(pKStk) tpa r2=r2;;				/* compute physical addr */			\
+(pKStk) ld8 r2=[r2];				/* __per_cpu_offset[cpu] */			\
+(pKStk) movl r17=THIS_CPU(cpu_info);;								\
+(pKStk) add r2=r17,r2;;				/*  cpu_info structure  */			\
+(pKStk) adds r2=IA64_CPUINFO_MCA_DATA,r2;;							\
+(pKStk) tpa r2=r2;;				/* compute physical addr */			\
+(pKStk) ld8 r2=[r2];;				/* Address of local cpu MCA/INIT save area */	\
+(pKStk) addl sp=IA64_INIT_STACK+IA64_STK_OFFSET-IA64_PT_REGS_SIZE, r2;				\
 (pUStk)	mov ar.rsc=0;		/* set enforced lazy mode, pl 0, little-endian, loadrs=0 */	\
 (pUStk)	addl r22=IA64_RBS_OFFSET,r1;		/* compute base of register backing store */	\
 	;;											\
diff -Nur linux-2.6.8.1.org/arch/ia64/mm/discontig.c linux-2.6.8.1/arch/ia64/mm/discontig.c
--- linux-2.6.8.1.org/arch/ia64/mm/discontig.c	2004-09-14 15:15:40.874890492 +0900
+++ linux-2.6.8.1/arch/ia64/mm/discontig.c	2004-09-14 14:46:57.596591290 +0900
@@ -4,6 +4,10 @@
  * Copyright (c) 2001 Tony Luck <tony.luck@intel.com>
  * Copyright (c) 2002 NEC Corp.
  * Copyright (c) 2002 Kimio Suganuma <k-suganuma@da.jp.nec.com>
+ * Copyright (c) 2003-2004 Silicon Graphics, Inc
+ *      Russ Anderson <rja@sgi.com>
+ *      Jesse Barnes <jbarnes@sgi.com>
+ *      Jack Steiner <steiner@sgi.com>
  */
 
 /*
@@ -21,6 +25,7 @@
 #include <asm/meminit.h>
 #include <asm/numa.h>
 #include <asm/sections.h>
+#include <asm/mca.h>
 
 /*
  * Track per-node information needed to setup the boot memory allocator, the
@@ -206,12 +211,33 @@
 }
 
 /**
+ * early_nr_phys_cpus_node - return number of physical cpus on a given node
+ * @node: node to check
+ *
+ * Count the number of physical cpus on @node.  These are cpus that actually
+ * exist.  We can't use nr_cpus_node() yet because
+ * acpi_boot_init() (which builds the node_to_cpu_mask array) hasn't been
+ * called yet.
+ */
+static int early_nr_phys_cpus_node(int node)
+{
+	int cpu, n = 0;
+
+	for (cpu = 0; cpu < NR_CPUS; cpu++)
+		if (node = node_cpuid[cpu].nid)
+			if ((cpu = 0) || node_cpuid[cpu].phys_id)
+				n++;
+
+	return n;
+}
+
+/**
  * early_nr_cpus_node - return number of cpus on a given node
  * @node: node to check
  *
  * Count the number of cpus on @node.  We can't use nr_cpus_node() yet because
  * acpi_boot_init() (which builds the node_to_cpu_mask array) hasn't been
- * called yet.
+ * called yet.  Note that node 0 will also count all non-existent cpus.
  */
 static int early_nr_cpus_node(int node)
 {
@@ -238,12 +264,15 @@
  *   |                        |
  *   |~~~~~~~~~~~~~~~~~~~~~~~~| <-- NODEDATA_ALIGN(start, node) for the first
  *   |    PERCPU_PAGE_SIZE *  |     start and length big enough
- *   |        NR_CPUS         |
+ *   |    cpus_on_this_node   | Node 0 will also have entries for all non-existent cpus.
  *   |------------------------|
  *   |   local pg_data_t *    |
  *   |------------------------|
  *   |  local ia64_node_data  |
  *   |------------------------|
+ *   |    MCA/INIT data *     |
+ *   |    cpus_on_this_node   |
+ *   |------------------------|
  *   |          ???           |
  *   |________________________|
  *
@@ -255,10 +284,11 @@
 static int __init find_pernode_space(unsigned long start, unsigned long len,
 				     int node)
 {
-	unsigned long epfn, cpu, cpus;
+	unsigned long epfn, cpu, cpus, phys_cpus;
 	unsigned long pernodesize = 0, pernode, pages, mapsize;
-	void *cpu_data;
+	void *cpu_data, *mca_data_phys;
 	struct bootmem_data *bdp = &mem_data[node].bootmem_data;
+	struct cpuinfo_ia64 *cpuinfo;
 
 	epfn = (start + len) >> PAGE_SHIFT;
 
@@ -281,9 +311,11 @@
 	 * for good alignment and alias prevention.
 	 */
 	cpus = early_nr_cpus_node(node);
+	phys_cpus = early_nr_phys_cpus_node(node);
 	pernodesize += PERCPU_PAGE_SIZE * cpus;
 	pernodesize += L1_CACHE_ALIGN(sizeof(pg_data_t));
 	pernodesize += L1_CACHE_ALIGN(sizeof(struct ia64_node_data));
+	pernodesize += L1_CACHE_ALIGN(sizeof(ia64_mca_cpu_t)) * phys_cpus;
 	pernodesize = PAGE_ALIGN(pernodesize);
 	pernode = NODEDATA_ALIGN(start, node);
 
@@ -302,6 +334,9 @@
 		mem_data[node].node_data = __va(pernode);
 		pernode += L1_CACHE_ALIGN(sizeof(struct ia64_node_data));
 
+		mca_data_phys = (void *)pernode;
+		pernode += L1_CACHE_ALIGN(sizeof(ia64_mca_cpu_t)) * phys_cpus;
+
 		mem_data[node].pgdat->bdata = bdp;
 		pernode += L1_CACHE_ALIGN(sizeof(pg_data_t));
 
@@ -314,6 +349,9 @@
 			if (node = node_cpuid[cpu].nid) {
 				memcpy(__va(cpu_data), __phys_per_cpu_start,
 				       __per_cpu_end - __per_cpu_start);
+				cpuinfo = (struct cpuinfo_ia64 *)(__va(cpu_data) + ((char *) &per_cpu__cpu_info - __per_cpu_start));
+				cpuinfo->ia64_mca_data = __va(mca_data_phys);
+				mca_data_phys += L1_CACHE_ALIGN(sizeof(ia64_mca_cpu_t));
 				__per_cpu_offset[cpu] = (char*)__va(cpu_data) -
 					__per_cpu_start;
 				cpu_data += PERCPU_PAGE_SIZE;
diff -Nur linux-2.6.8.1.org/include/asm-ia64/mca.h linux-2.6.8.1/include/asm-ia64/mca.h
--- linux-2.6.8.1.org/include/asm-ia64/mca.h	2004-09-14 15:15:40.870007680 +0900
+++ linux-2.6.8.1/include/asm-ia64/mca.h	2004-09-13 14:08:18.000000000 +0900
@@ -5,6 +5,7 @@
  * Copyright (C) 1999, 2004 Silicon Graphics, Inc.
  * Copyright (C) Vijay Chander (vijay@engr.sgi.com)
  * Copyright (C) Srinivasa Thirumalachar (sprasad@engr.sgi.com)
+ * Copyright (C) Russ Anderson <rja@sgi.com>
  */
 
 #ifndef _ASM_IA64_MCA_H
@@ -107,6 +108,14 @@
 						 */
 } ia64_mca_os_to_sal_state_t;
 
+typedef struct ia64_mca_cpu_s {
+	u64		ia64_mca_proc_state_dump[512];
+	u64		ia64_mca_stack[1024] __attribute__((aligned(16)));
+	u64		ia64_mca_stackframe[32];
+	u64		ia64_mca_bspstore[1024];
+	u64		ia64_init_stack[KERNEL_STACK_SIZE/8] __attribute__((aligned(16)));
+} ia64_mca_cpu_t;
+
 extern void ia64_mca_init(void);
 extern void ia64_os_mca_dispatch(void);
 extern void ia64_os_mca_dispatch_end(void);
diff -Nur linux-2.6.8.1.org/include/asm-ia64/processor.h linux-2.6.8.1/include/asm-ia64/processor.h
--- linux-2.6.8.1.org/include/asm-ia64/processor.h	2004-09-14 15:15:40.876843617 +0900
+++ linux-2.6.8.1/include/asm-ia64/processor.h	2004-09-13 14:08:18.000000000 +0900
@@ -2,6 +2,8 @@
 #define _ASM_IA64_PROCESSOR_H
 
 /*
+ * Copyright (C) 2004 Silicon Graphics, Inc
+ *      Russ Anderson <rja@sgi.com>
  * Copyright (C) 1998-2004 Hewlett-Packard Co
  *	David Mosberger-Tang <davidm@hpl.hp.com>
  *	Stephane Eranian <eranian@hpl.hp.com>
@@ -171,6 +173,7 @@
 #ifdef CONFIG_NUMA
 	struct ia64_node_data *node_data;
 #endif
+	__u64 *ia64_mca_data;	/* prt to MCA/INIT processor state */
 };
 
 DECLARE_PER_CPU(struct cpuinfo_ia64, cpu_info);