From f4619025a51747a3788fd1bb6bdc46e368a889a7 Mon Sep 17 00:00:00 2001 From: Russell King Date: Thu, 12 Jan 2006 17:17:57 +0000 Subject: [PATCH] [ARM] Allow r2 to be passed through the decompressor to the kernel This is part of a patch from Marc Singer to allow r2 to be passed to the kernel. Marc's original comments follow: This revised R2 (atags pointer) patch incorporates comments from Nico Pitre and Ben Dooks. It modifies the head.S files such that the R2 value set by the bootloader is conveyed to the kernel startup code. The kernel head.S heuristically validates the pointer. It will set R2 to zero if it believes the pointer is invalid. Presently, it requires that the ATAGS list reside in the first 16KiB of physical RAM. Relaxing this contraint may be both desirable as well as tricky. Signed-off-by: Marc Singer Signed-off-by: Russell King --- arch/arm/boot/compressed/head.S | 46 ++++++++++++++++++--------------- 1 file changed, 25 insertions(+), 21 deletions(-) diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S index 6abafb6f1844..aaa47400eb9c 100644 --- a/arch/arm/boot/compressed/head.S +++ b/arch/arm/boot/compressed/head.S @@ -84,7 +84,7 @@ kputc #'\n' kphex r5, 8 /* decompressed kernel start */ kputc #'-' - kphex r8, 8 /* decompressed kernel end */ + kphex r9, 8 /* decompressed kernel end */ kputc #'>' kphex r4, 8 /* kernel execution address */ kputc #'\n' @@ -116,7 +116,7 @@ start: .word start @ absolute load/run zImage address .word _edata @ zImage end address 1: mov r7, r1 @ save architecture ID - mov r8, #0 @ save r0 + mov r8, r2 @ save atags pointer #ifndef __ARM_ARCH_2__ /* @@ -144,7 +144,7 @@ not_angel: /* * some architecture specific code can be inserted - * by the linker here, but it should preserve r7 and r8. + * by the linker here, but it should preserve r7, r8, and r9. */ .text @@ -249,16 +249,17 @@ not_relocated: mov r0, #0 * r5 = decompressed kernel start * r6 = processor ID * r7 = architecture ID - * r8-r14 = unused + * r8 = atags pointer + * r9-r14 = corrupted */ add r1, r5, r0 @ end of decompressed kernel adr r2, reloc_start ldr r3, LC1 add r3, r2, r3 -1: ldmia r2!, {r8 - r13} @ copy relocation code - stmia r1!, {r8 - r13} - ldmia r2!, {r8 - r13} - stmia r1!, {r8 - r13} +1: ldmia r2!, {r9 - r14} @ copy relocation code + stmia r1!, {r9 - r14} + ldmia r2!, {r9 - r14} + stmia r1!, {r9 - r14} cmp r2, r3 blo 1b @@ -308,11 +309,12 @@ params: ldr r0, =params_phys * r4 = kernel execution address * r6 = processor ID * r7 = architecture number - * r8 = run-time address of "start" + * r8 = atags pointer + * r9 = run-time address of "start" (???) * On exit, - * r1, r2, r3, r8, r9, r12 corrupted + * r1, r2, r3, r9, r10, r12 corrupted * This routine must preserve: - * r4, r5, r6, r7 + * r4, r5, r6, r7, r8 */ .align 5 cache_on: mov r3, #8 @ cache_on function @@ -326,15 +328,15 @@ __setup_mmu: sub r3, r4, #16384 @ Page directory size * bits for the RAM area only. */ mov r0, r3 - mov r8, r0, lsr #18 - mov r8, r8, lsl #18 @ start of RAM - add r9, r8, #0x10000000 @ a reasonable RAM size + mov r9, r0, lsr #18 + mov r9, r9, lsl #18 @ start of RAM + add r10, r9, #0x10000000 @ a reasonable RAM size mov r1, #0x12 orr r1, r1, #3 << 10 add r2, r3, #16384 1: cmp r1, r8 @ if virt > start of RAM orrhs r1, r1, #0x0c @ set cacheable, bufferable - cmp r1, r9 @ if virt > end of RAM + cmp r1, r10 @ if virt > end of RAM bichs r1, r1, #0x0c @ clear cacheable, bufferable str r1, [r0], #4 @ 1:1 mapping add r1, r1, #1048576 @@ -403,26 +405,28 @@ __common_cache_on: * r5 = decompressed kernel start * r6 = processor ID * r7 = architecture ID - * r8-r14 = unused + * r8 = atags pointer + * r9-r14 = corrupted */ .align 5 -reloc_start: add r8, r5, r0 +reloc_start: add r9, r5, r0 debug_reloc_start mov r1, r4 1: .rept 4 - ldmia r5!, {r0, r2, r3, r9 - r13} @ relocate kernel - stmia r1!, {r0, r2, r3, r9 - r13} + ldmia r5!, {r0, r2, r3, r10 - r14} @ relocate kernel + stmia r1!, {r0, r2, r3, r10 - r14} .endr - cmp r5, r8 + cmp r5, r9 blo 1b debug_reloc_end call_kernel: bl cache_clean_flush bl cache_off - mov r0, #0 + mov r0, #0 @ must be zero mov r1, r7 @ restore architecture number + mov r2, r8 @ restore atags pointer mov pc, r4 @ call kernel /* -- 2.20.1