OriginalAuthor: Mike Kasick <[email protected]> This is needed if this kernel is booted using kexec-hardboot[1], because atags need to be in direct-mapped region, usually the first 16kB of RAM.
Ported from Jens Andersen <[email protected]>'s kernel for Asus TF201 [2]. [1] Hardboot: http://forum.xda-developers.com/showthread.php?t=1266827 [2] Original repository: http://git.io/EXpn2A Signed-off-by: Vojtech Bocek <[email protected]> --- arch/arm/boot/compressed/Makefile | 3 +++ arch/arm/boot/compressed/head.S | 44 ++++++++++++++++++++++++++++++++++++- arch/arm/boot/compressed/misc.c | 22 +++++++++++++++++++ 3 files changed, 68 insertions(+), 1 deletion(-) diff --git a/arch/arm/boot/compressed/Makefile b/arch/arm/boot/compressed/Makefile index 0c74a6f..7643b37 100644 --- a/arch/arm/boot/compressed/Makefile +++ b/arch/arm/boot/compressed/Makefile @@ -111,6 +111,9 @@ endif ifeq ($(CONFIG_CPU_ENDIAN_BE8),y) LDFLAGS_vmlinux += --be8 endif +ifneq ($(PARAMS_PHYS),) +LDFLAGS_vmlinux += --defsym params_phys=$(PARAMS_PHYS) +endif # ? LDFLAGS_vmlinux += -p # Report unresolved symbol references diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S index 24701d6..5773670 100644 --- a/arch/arm/boot/compressed/head.S +++ b/arch/arm/boot/compressed/head.S @@ -133,7 +133,9 @@ start: .word _edata @ zImage end address THUMB( .thumb ) 1: mov r7, r1 @ save architecture ID - mov r8, r2 @ save atags pointer + teq r0, #0 @ Check for kexec_boot_atags. + movne r8, r0 @ Save kexec_boot_tags. + moveq r8, r2 @ save atags pointer #ifndef __ARM_ARCH_2__ /* @@ -348,6 +350,44 @@ not_relocated: mov r0, #0 add r2, sp, #0x10000 @ 64k max mov r3, r7 bl decompress_kernel + +/* Copy the kernel tagged list (atags): + * + * The kernel requires atags to be located in a direct-mapped region, + * usually below the kernel in the first 16 kB of RAM. If they're above + * (the start of) the kernel, they need to be copied to a suitable + * location, e.g., the machine-defined params_phys. + * + * The assumption is that the tags will only be "out of place" if the + * decompressor code is also, so copying is implemented only in the "won't + * overwrite" case (which should be fixed). Still need to make sure that + * the copied tags don't overwrite either the kernel or decompressor code + * (or rather, the remainder of it since everything up to here has already + * been executed). + * + * r4: zreladdr (kernel start) + * r8: atags */ + + /* No need to copy atags if they're already below kernel */ + cmp r8, r4 + blo call_kernel + + /* r1: min(zreladdr, pc) */ + mov r1, pc + cmp r4, r1 + movlo r1, r4 + + /* Compute max space for atags, if max <= 0 don't copy. */ + ldr r0, =params_phys @ dest + subs r2, r1, r0 @ max = min(zreladdr, pc) - dest + bls call_kernel + + /* Copy atags to params_phys. */ + mov r1, r8 @ src + bl copy_atags + mov r8, r0 + +call_kernel: bl cache_clean_flush bl cache_off mov r0, #0 @ must be zero @@ -356,6 +396,8 @@ not_relocated: mov r0, #0 ARM( mov pc, r4 ) @ call kernel THUMB( bx r4 ) @ entry point is always ARM + .ltorg + .align 2 .type LC0, #object LC0: .word LC0 @ r1 diff --git a/arch/arm/boot/compressed/misc.c b/arch/arm/boot/compressed/misc.c index 832d372..c082769 100644 --- a/arch/arm/boot/compressed/misc.c +++ b/arch/arm/boot/compressed/misc.c @@ -25,6 +25,7 @@ unsigned int __machine_arch_type; #include <linux/stddef.h> /* for NULL */ #include <linux/linkage.h> #include <asm/string.h> +#include <asm/setup.h> static void putstr(const char *ptr); @@ -192,3 +193,24 @@ decompress_kernel(unsigned long output_start, unsigned long free_mem_ptr_p, else putstr(" done, booting the kernel.\n"); } + +const struct tag *copy_atags(struct tag *dest, const struct tag *src, size_t max) +{ + struct tag *tag; + size_t size; + + /* Find the last tag (ATAG_NONE). */ + for_each_tag(tag, (struct tag *)src) + continue; + + /* Include the last tag in copy. */ + size = (char *)tag - (char *)src + sizeof(struct tag_header); + + /* If there's not enough room, just use original and hope it works. */ + if (size > max) + return src; + + memcpy(dest, src, size); + + return dest; +} -- 1.7.10.4 -- Mailing list: https://launchpad.net/~ubuntu-phone Post to : [email protected] Unsubscribe : https://launchpad.net/~ubuntu-phone More help : https://help.launchpad.net/ListHelp
