Thread (15 messages) flat view 15 messages, 4 authors, 2011-02-07

[RFC] arm: Defer lookup of machine_type and vet of atags to setup.c

From: Russell King - ARM Linux <hidden>
Date: 2011-01-12 17:26:09
Also in: lkml
Subsystem: arm port, the rest · Maintainers: Russell King, Linus Torvalds

On Wed, Jan 12, 2011 at 10:16:44AM -0700, Grant Likely wrote:
On Wed, Jan 12, 2011 at 9:53 AM, Nicolas Pitre [off-list ref] wrote:
quoted
On Wed, 12 Jan 2011, Grant Likely wrote:
quoted
Actually it looks like the real problem is that the mmu has been
turned on, but the virtual mappings for devices have not yet been
established, and so the debug macros aren't using a valid address.
A temporary virtual mapping should be there -- look for addruart in
head.S.
Hi Russell and Nicolas,

Oops, yes all the early debug stuff works fine.  Stupid human trick on
my end, but I've sorted it out now.  Thanks for the help.  I'll have
patches to post later today.
I just hacked this up, and on Versatile (real hardware) it produces
the below for an invalid r1 value - and of course works for a proper r1
value.

Uncompressing Linux... done, booting the kernel.

Error: unrecognized/unsupported machine ID (r1 = 0x00123456).

Available machine support:

ID (hex)        NAME
00000183        ARM-Versatile PB
0000025e        ARM-Versatile AB

Please check your kernel config and/or bootloader.
diff --git a/arch/arm/kernel/head-common.S b/arch/arm/kernel/head-common.S
index bbecaac..c84b57d 100644
--- a/arch/arm/kernel/head-common.S
+++ b/arch/arm/kernel/head-common.S
@@ -25,81 +25,6 @@
  * machine ID for example).
  */
 	__HEAD
-__error_a:
-#ifdef CONFIG_DEBUG_LL
-	mov	r4, r1				@ preserve machine ID
-	adr	r0, str_a1
-	bl	printascii
-	mov	r0, r4
-	bl	printhex8
-	adr	r0, str_a2
-	bl	printascii
-	adr	r3, __lookup_machine_type_data
-	ldmia	r3, {r4, r5, r6}		@ get machine desc list
-	sub	r4, r3, r4			@ get offset between virt&phys
-	add	r5, r5, r4			@ convert virt addresses to
-	add	r6, r6, r4			@ physical address space
-1:	ldr	r0, [r5, #MACHINFO_TYPE]	@ get machine type
-	bl	printhex8
-	mov	r0, #'\t'
-	bl	printch
-	ldr     r0, [r5, #MACHINFO_NAME]	@ get machine name
-	add	r0, r0, r4
-	bl	printascii
-	mov	r0, #'\n'
-	bl	printch
-	add	r5, r5, #SIZEOF_MACHINE_DESC	@ next machine_desc
-	cmp	r5, r6
-	blo	1b
-	adr	r0, str_a3
-	bl	printascii
-	b	__error
-ENDPROC(__error_a)
-
-str_a1:	.asciz	"\nError: unrecognized/unsupported machine ID (r1 = 0x"
-str_a2:	.asciz	").\n\nAvailable machine support:\n\nID (hex)\tNAME\n"
-str_a3:	.asciz	"\nPlease check your kernel config and/or bootloader.\n"
-	.align
-#endif
-
-/*
- * Lookup machine architecture in the linker-build list of architectures.
- * Note that we can't use the absolute addresses for the __arch_info
- * lists since we aren't running with the MMU on (and therefore, we are
- * not in the correct address space).  We have to calculate the offset.
- *
- *  r1 = machine architecture number
- * Returns:
- *  r3, r4, r6 corrupted
- *  r5 = mach_info pointer in physical address space
- */
-__lookup_machine_type:
-	adr	r3, __lookup_machine_type_data
-	ldmia	r3, {r4, r5, r6}
-	sub	r3, r3, r4			@ get offset between virt&phys
-	add	r5, r5, r3			@ convert virt addresses to
-	add	r6, r6, r3			@ physical address space
-1:	ldr	r3, [r5, #MACHINFO_TYPE]	@ get machine type
-	teq	r3, r1				@ matches loader number?
-	beq	2f				@ found
-	add	r5, r5, #SIZEOF_MACHINE_DESC	@ next machine_desc
-	cmp	r5, r6
-	blo	1b
-	mov	r5, #0				@ unknown machine
-2:	mov	pc, lr
-ENDPROC(__lookup_machine_type)
-
-/*
- * Look in arch/arm/kernel/arch.[ch] for information about the
- * __arch_info structures.
- */
-	.align	2
-	.type	__lookup_machine_type_data, %object
-__lookup_machine_type_data:
-	.long	.
-	.long	__arch_info_begin
-	.long	__arch_info_end
-	.size	__lookup_machine_type_data, . - __lookup_machine_type_data
 
 /* Determine validity of the r2 atags pointer.  The heuristic requires
  * that the pointer be aligned, in the first 16k of physical RAM and
@@ -107,8 +32,6 @@ __lookup_machine_type_data:
  * of this function may be more lenient with the physical address and
  * may also be able to move the ATAGS block if necessary.
  *
- * r8  = machinfo
- *
  * Returns:
  *  r2 either valid atags pointer, or zero
  *  r5, r6 corrupted
@@ -183,17 +106,6 @@ __mmap_switched_data:
 	.size	__mmap_switched_data, . - __mmap_switched_data
 
 /*
- * This provides a C-API version of __lookup_machine_type
- */
-ENTRY(lookup_machine_type)
-	stmfd	sp!, {r4 - r6, lr}
-	mov	r1, r0
-	bl	__lookup_machine_type
-	mov	r0, r5
-	ldmfd	sp!, {r4 - r6, pc}
-ENDPROC(lookup_machine_type)
-
-/*
  * This provides a C-API version of __lookup_processor_type
  */
 ENTRY(lookup_processor_type)
diff --git a/arch/arm/kernel/head-nommu.S b/arch/arm/kernel/head-nommu.S
index 814ce1a..6b1e0ad 100644
--- a/arch/arm/kernel/head-nommu.S
+++ b/arch/arm/kernel/head-nommu.S
@@ -44,9 +44,6 @@ ENTRY(stext)
 	bl	__lookup_processor_type		@ r5=procinfo r9=cpuid
 	movs	r10, r5				@ invalid processor (r5=0)?
 	beq	__error_p				@ yes, error 'p'
-	bl	__lookup_machine_type		@ r5=machinfo
-	movs	r8, r5				@ invalid machine (r5=0)?
-	beq	__error_a			@ yes, error 'a'
 
 	adr	lr, BSYM(__after_proc_init)	@ return (PIC) address
  ARM(	add	pc, r10, #PROCINFO_INITFUNC	)
diff --git a/arch/arm/kernel/head.S b/arch/arm/kernel/head.S
index 06aed19..084db6c 100644
--- a/arch/arm/kernel/head.S
+++ b/arch/arm/kernel/head.S
@@ -87,14 +87,10 @@ ENTRY(stext)
 	movs	r10, r5				@ invalid processor (r5=0)?
  THUMB( it	eq )		@ force fixup-able long branch encoding
 	beq	__error_p			@ yes, error 'p'
-	bl	__lookup_machine_type		@ r5=machinfo
-	movs	r8, r5				@ invalid machine (r5=0)?
- THUMB( it	eq )		@ force fixup-able long branch encoding
-	beq	__error_a			@ yes, error 'a'
 
 	/*
 	 * r1 = machine no, r2 = atags,
-	 * r8 = machinfo, r9 = cpuid, r10 = procinfo
+	 * r9 = cpuid, r10 = procinfo
 	 */
 	bl	__vet_atags
 #ifdef CONFIG_SMP_ON_UP
@@ -108,7 +104,7 @@ ENTRY(stext)
 	/*
 	 * The following calls CPU specific code in a position independent
 	 * manner.  See arch/arm/mm/proc-*.S for details.  r10 = base of
-	 * xxx_proc_info structure selected by __lookup_machine_type
+	 * xxx_proc_info structure selected by __lookup_processor_type
 	 * above.  On return, the CPU will be ready for the MMU to be
 	 * turned on, and r0 will hold the CPU control register value.
 	 */
@@ -127,7 +123,6 @@ ENDPROC(stext)
  * amount which are required to get the kernel running, which
  * generally means mapping in the kernel code.
  *
- * r8  = machinfo
  * r9  = cpuid
  * r10 = procinfo
  *
diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index 7c5499d..eb952a7 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -308,7 +308,44 @@ static void __init cacheid_init(void)
  * already provide the required functionality.
  */
 extern struct proc_info_list *lookup_processor_type(unsigned int);
-extern struct machine_desc *lookup_machine_type(unsigned int);
+
+static void __init early_print(const char *str, ...)
+{
+	extern void printascii(const char *);
+	char buf[256];
+	va_list ap;
+
+	va_start(ap, str);
+	vsnprintf(buf, sizeof(buf), str, ap);
+	va_end(ap);
+
+#ifdef CONFIG_DEBUG_LL
+	printascii(buf);
+#endif
+	printk("%s", buf);
+}
+
+static struct machine_desc * __init lookup_machine_type(unsigned int type)
+{
+	extern struct machine_desc __arch_info_begin[], __arch_info_end[];
+	struct machine_desc *p;
+
+	for (p = __arch_info_begin; p < __arch_info_end; p++)
+		if (type == p->nr)
+			return p;
+
+	early_print("\n"
+		"Error: unrecognized/unsupported machine ID (r1 = 0x%08x).\n\n"
+		"Available machine support:\n\nID (hex)\tNAME\n", type);
+
+	for (p = __arch_info_begin; p < __arch_info_end; p++)
+		early_print("%08x\t%s\n", p->nr, p->name);
+
+	early_print("\nPlease check your kernel config and/or bootloader.\n");
+
+	while (true)
+		/* can't use cpu_relax() here as it may require MMU setup */;
+}
 
 static void __init feat_v6_fixup(void)
 {
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