[ARM] 4736/1: Export atags to userspace and allow kexec to use customised atags

Currently, the atags used by kexec are fixed to the ones originally used
to boot the kernel. This is less than ideal as changing the commandline,
initrd and other options would be a useful feature.

This patch exports the atags used for the current kernel to userspace
through an "atags" file in procfs. The presence of the file is
controlled by its own Kconfig option and cleans up several ifdef blocks
into a separate file. The tags for the new kernel are assumed to be at
a fixed location before the kernel image itself. The location of the
tags used to boot the original kernel is unimportant and no longer
saved.

Based on a patch from Uli Luckas <u.luckas@road.de>

Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
Acked-by: Uli Luckas <u.luckas@road.de>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 4 insertions, 26 deletions

diff --git a/arch/arm/kernel/relocate_kernel.S b/arch/arm/kernel/relocate_kernel.S
index 062c111c572f..61930eb09029 100644
--- a/arch/arm/kernel/relocate_kernel.S
+++ b/arch/arm/kernel/relocate_kernel.S
@@ -7,23 +7,6 @@
         .globl relocate_new_kernel
 relocate_new_kernel:
 
-        /* Move boot params back to where the kernel expects them */
-
-        ldr     r0,kexec_boot_params_address
-        teq     r0,#0
-        beq     8f
-
-        ldr     r1,kexec_boot_params_copy
-        mov     r6,#KEXEC_BOOT_PARAMS_SIZE/4
-7:
-        ldr     r5,[r1],#4
-        str     r5,[r0],#4
-        subs    r6,r6,#1
-        bne     7b
-
-8:
-        /* Boot params moved, now go on with the kernel */
-
         ldr     r0,kexec_indirection_page
         ldr     r1,kexec_start_address
 
@@ -67,7 +50,7 @@ relocate_new_kernel:
         mov lr,r1
         mov r0,#0
         ldr r1,kexec_mach_type
-        ldr r2,kexec_boot_params_address
+        ldr r2,kexec_boot_atags
         mov pc,lr
 
         .globl kexec_start_address
@@ -82,14 +65,9 @@ kexec_indirection_page:
 kexec_mach_type:
         .long   0x0
 
-        /* phy addr where new kernel will expect to find boot params */
-        .globl kexec_boot_params_address
-kexec_boot_params_address:
-        .long   0x0
-
-        /* phy addr where old kernel put a copy of orig boot params */
-        .globl kexec_boot_params_copy
-kexec_boot_params_copy:
+        /* phy addr of the atags for the new kernel */
+        .globl kexec_boot_atags
+kexec_boot_atags:
         .long   0x0
 
 relocate_new_kernel_end: