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Date: Mon, 10 Jan 2011 19:15:53 -0700
From: Grant Likely <grant.likely@...retlab.ca>
To: Russell King <linux@....linux.org.uk>,
linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Cc: Catalin Marinas <catalin.marinas@....com>,
Jeremy Kerr <jeremy.kerr@...onical.com>,
Nicolas Pitre <nicolas.pitre@...onical.com>
Subject: [RFC] arm: Defer lookup of machine_type and vet of atags to setup.c
Since the debug macros no longer depend on the machine type
information, both the machine type lookup and the atags vetting can be
deferred to setup_arch() in setup.c which simplifies the code
somewhat.
This patch removes both __machine_type_lookup and __vet_atags() from
head.S. The atags vetting is moved to setup_arch(). machine_type
lookup is already called from setup_machine() in addition to where it
was called from head.S.
I've tried to preserve the existing behaviour in this patch so the
extra atags vetting is only using when CONFIG_MMU is selected. I may
be being overly cautious, and if so then it is probably possible to
simplify the code further.
Signed-off-by: Grant Likely <grant.likely@...retlab.ca>
---
Hi Russell,
I'm not sure if this is a valid change or not, but from what I can
tell it looks like machine and atag processing no longer needs
to be handled as early as head.S. Please take a look and let me know
what you think.
I've boot tested this on Tegra and versatile qemu, but that's about
it.
Thanks,
g.
arch/arm/kernel/head-common.S | 35 -----------------------------------
arch/arm/kernel/head.S | 5 -----
arch/arm/kernel/setup.c | 16 ++++++++++++++++
3 files changed, 16 insertions(+), 40 deletions(-)
diff --git a/arch/arm/kernel/head-common.S b/arch/arm/kernel/head-common.S
index bbecaac..7956a48 100644
--- a/arch/arm/kernel/head-common.S
+++ b/arch/arm/kernel/head-common.S
@@ -11,10 +11,6 @@
*
*/
-#define ATAG_CORE 0x54410001
-#define ATAG_CORE_SIZE ((2*4 + 3*4) >> 2)
-#define ATAG_CORE_SIZE_EMPTY ((2*4) >> 2)
-
/*
* Exception handling. Something went wrong and we can't proceed. We
* ought to tell the user, but since we don't have any guarantee that
@@ -101,37 +97,6 @@ __lookup_machine_type_data:
.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
- * that the ATAG_CORE marker is first and present. Future revisions
- * 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
- */
-__vet_atags:
- tst r2, #0x3 @ aligned?
- bne 1f
-
- ldr r5, [r2, #0] @ is first tag ATAG_CORE?
- cmp r5, #ATAG_CORE_SIZE
- cmpne r5, #ATAG_CORE_SIZE_EMPTY
- bne 1f
- ldr r5, [r2, #4]
- ldr r6, =ATAG_CORE
- cmp r5, r6
- bne 1f
-
- mov pc, lr @ atag pointer is ok
-
-1: mov r2, #0
- mov pc, lr
-ENDPROC(__vet_atags)
-
/*
* The following fragment of code is executed with the MMU on in MMU mode,
* and uses absolute addresses; this is not position independent.
diff --git a/arch/arm/kernel/head.S b/arch/arm/kernel/head.S
index 6bd82d2..9c0e938 100644
--- a/arch/arm/kernel/head.S
+++ b/arch/arm/kernel/head.S
@@ -87,11 +87,6 @@ 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'
- bl __vet_atags
#ifdef CONFIG_SMP_ON_UP
bl __fixup_smp
#endif
diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index 336f14e..cd28089 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -814,6 +814,22 @@ void __init setup_arch(char **cmdline_p)
if (mdesc->soft_reboot)
reboot_setup("s");
+#if defined(CONFIG_MMU)
+ /*
+ * Determine validity of the atags pointer. The heuristic requires
+ * that the pointer be aligned, and that the ATAG_CORE marker is
+ * first and present.
+ */
+ if (__atags_pointer & 0x3)
+ __atags_pointer = 0;
+ if (__atags_pointer) {
+ struct tag *t = phys_to_virt(__atags_pointer);
+ if ((t->hdr.size != tag_size(tag_core)) &&
+ (t->hdr.size != sizeof(struct tag_header)) &&
+ (t->hdr.tag != ATAG_CORE))
+ __atags_pointer = 0;
+ }
+#endif
if (__atags_pointer)
tags = phys_to_virt(__atags_pointer);
else if (mdesc->boot_params)
--
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