From 161b3589ea19ad262a2eebbf7b4f10aeb6812f35 Mon Sep 17 00:00:00 2001 From: Graeme Russ Date: Thu, 7 Oct 2010 20:03:29 +1100 Subject: [PATCH] x86: Place global data below stack before entering C By reserving space for the Global Data immediately below the stack during assembly level initialisation, the C declaration of the static global data can be removed, along with the 'RAM Bootstrap' function. This results in cleaner code, and the ability to pass boot-up flags from assembler into C --- arch/i386/cpu/start.S | 8 ++++++ arch/i386/include/asm/global_data.h | 24 +++++++++++++++-- arch/i386/lib/board.c | 42 +++++------------------------ 3 files changed, 37 insertions(+), 37 deletions(-) diff --git a/arch/i386/cpu/start.S b/arch/i386/cpu/start.S index 66ff4f3e06..cff4637589 100644 --- a/arch/i386/cpu/start.S +++ b/arch/i386/cpu/start.S @@ -25,6 +25,7 @@ #include #include +#include .section .text @@ -127,6 +128,13 @@ mem_ok: /* Set the upper memory limit parameter */ subl $CONFIG_SYS_STACK_SIZE, %eax + /* Reserve space for global data */ + subl $(GD_SIZE * 4), %eax + + /* %eax points to the global data structure */ + movl %esp, (GD_RAM_SIZE * 4)(%eax) + movl %ebx, (GD_FLAGS * 4)(%eax) + call board_init_f /* Enter, U-boot! */ /* indicate (lack of) progress */ diff --git a/arch/i386/include/asm/global_data.h b/arch/i386/include/asm/global_data.h index 3a9adc9c66..456f606ec8 100644 --- a/arch/i386/include/asm/global_data.h +++ b/arch/i386/include/asm/global_data.h @@ -33,6 +33,8 @@ * Keep it *SMALL* and remember to set CONFIG_SYS_GBL_DATA_SIZE > sizeof(gd_t) */ +#ifndef __ASSEMBLY__ + typedef struct { bd_t *bd; unsigned long flags; @@ -49,6 +51,26 @@ typedef struct { char env_buf[32]; /* buffer for getenv() before reloc. */ } gd_t; +extern gd_t *gd; + +#endif + +/* Word Offsets into Global Data - MUST match struct gd_t */ +#define GD_BD 0 +#define GD_FLAGS 1 +#define GD_BAUDRATE 2 +#define GD_HAVE_CONSOLE 3 +#define GD_RELOC_OFF 4 +#define GD_ENV_ADDR 5 +#define GD_ENV_VALID 6 +#define GD_CPU_CLK 7 +#define GD_BUS_CLK 8 +#define GD_RAM_SIZE 9 +#define GD_RESET_STATUS 10 +#define GD_JT 11 + +#define GD_SIZE 12 + /* * Global Data Flags */ @@ -61,8 +83,6 @@ typedef struct { #define GD_FLG_DISABLE_CONSOLE 0x00040 /* Disable console (in & out) */ #define GD_FLG_ENV_READY 0x00080 /* Environment imported into hash table */ -extern gd_t *gd; - #define DECLARE_GLOBAL_DATA_PTR #endif /* __ASM_GBL_DATA_H */ diff --git a/arch/i386/lib/board.c b/arch/i386/lib/board.c index 5002203ec8..00976a5d49 100644 --- a/arch/i386/lib/board.c +++ b/arch/i386/lib/board.c @@ -54,8 +54,6 @@ extern ulong _i386boot_rel_dyn_end; extern ulong _i386boot_bss_start; extern ulong _i386boot_bss_size; -void ram_bootstrap (void *, ulong); - const char version_string[] = U_BOOT_VERSION" (" U_BOOT_DATE " - " U_BOOT_TIME ")"; @@ -164,13 +162,12 @@ init_fnc_t *init_sequence[] = { NULL, }; -static gd_t gd_data; gd_t *gd; /* * Load U-Boot into RAM, initialize BSS, perform relocation adjustments */ -void board_init_f (ulong stack_limit) +void board_init_f (ulong gdp) { void *text_start = &_i386boot_text_start; void *u_boot_cmd_end = &__u_boot_cmd_end; @@ -184,12 +181,9 @@ void board_init_f (ulong stack_limit) ulong rel_offset; Elf32_Rel *re; - void (*start_func)(void *, ulong); - uboot_size = (ulong)u_boot_cmd_end - (ulong)text_start; - dest_addr = (void *)stack_limit - (uboot_size + (ulong)bss_size); + dest_addr = (void *)gdp - (uboot_size + (ulong)bss_size); rel_offset = text_start - dest_addr; - start_func = ram_bootstrap - rel_offset; /* First stage CPU initialization */ if (cpu_init_f() != 0) @@ -213,38 +207,16 @@ void board_init_f (ulong stack_limit) *(ulong *)(re->r_offset - rel_offset) -= (Elf32_Addr)rel_offset; } + ((gd_t *)gdp)->reloc_off = rel_offset; + ((gd_t *)gdp)->flags |= GD_FLG_RELOC; + /* Enter the relocated U-Boot! */ - start_func(dest_addr, rel_offset); + (board_init_r - rel_offset)((gd_t *)gdp, (ulong)dest_addr); + /* NOTREACHED - board_init_f() does not return */ while(1); } -/* - * We cannot initialize gd_data in board_init_f() because we would be - * attempting to write to flash (I have even tried using manual relocation - * adjustments on pointers but it just won't work) and board_init_r() does - * not have enough arguments to allow us to pass the relocation offset - * straight up. This bootstrap function (which runs in RAM) is used to - * setup gd_data in order to pass the relocation offset to the rest of - * U-Boot. - * - * TODO: The compiler optimization barrier is intended to stop GCC from - * optimizing this function into board_init_f(). It seems to work without - * it, but I've left it in to be sure. I think also that the barrier in - * board_init_r() is no longer needed, but left it in 'just in case' - */ -void ram_bootstrap (void *dest_addr, ulong rel_offset) -{ - /* compiler optimization barrier needed for GCC >= 3.4 */ - __asm__ __volatile__("": : :"memory"); - - /* tell others: relocation done */ - gd_data.reloc_off = rel_offset; - gd_data.flags |= GD_FLG_RELOC; - - board_init_r(&gd_data, (ulong)dest_addr); -} - void board_init_r(gd_t *id, ulong dest_addr) { char *s;