diff --git a/arch/x86/stage1.c b/arch/x86/stage1.c index dcd0ab3942..2ae6f259ce 100644 --- a/arch/x86/stage1.c +++ b/arch/x86/stage1.c @@ -70,10 +70,19 @@ void init_archive(struct mem_file *archive) } +/* + * The name is slightly misleading because this is the initial stack pointer, + * not the address of the first element on the stack. + */ void *bottom_of_stack(void) { - /* -4-4 because CONFIG_CARBASE + CONFIG_CARSIZE - 4 is initial %esp */ - return (void *)(CONFIG_CARBASE + CONFIG_CARSIZE - 4 - 4); + /* -4 because CONFIG_CARBASE + CONFIG_CARSIZE - 4 is initial %esp */ + return (void *)(CONFIG_CARBASE + CONFIG_CARSIZE - 4); +} + +struct global_vars *global_vars(void) +{ + return (struct global_vars *)(bottom_of_stack() - sizeof(struct global_vars)); } void dump_mem_range(int msg_level, unsigned char *buf, int size) diff --git a/include/arch/x86/cpu.h b/include/arch/x86/cpu.h index 51d2aa3630..725a8ed3b2 100644 --- a/include/arch/x86/cpu.h +++ b/include/arch/x86/cpu.h @@ -202,6 +202,7 @@ static inline __attribute__((always_inline)) void hlt(void) } SHARED(bottom_of_stack, void *, void); +SHARED(global_vars, struct global_vars *, void); #ifdef CONFIG_CONSOLE_BUFFER #define PRINTK_BUF_SIZE_CAR (CONFIG_CARSIZE / 2) diff --git a/include/console.h b/include/console.h index 0a23c0b114..920d7db653 100644 --- a/include/console.h +++ b/include/console.h @@ -59,6 +59,18 @@ struct printk_buffer { }; #endif +/* + * If you change struct global_vars in any way, you have to fix all stage0 asm + * code. The stage0 asm code modification is nontrivial (size of the struct, + * alignment, initialization, order of struct members, initialization). + * Depending on your compiler, real breakage may happen. + */ +struct global_vars { +#ifdef CONFIG_CONSOLE_BUFFER + struct printk_buffer *printk_buffer; +#endif +}; + SHARED_WITH_ATTRIBUTES(printk, int, __attribute__((format (printf, 2, 3))), int msg_level, const char *fmt, ...); SHARED(banner, void, int msg_level, const char *msg); diff --git a/lib/console.c b/lib/console.c index 9cad3b7b7f..6557638578 100644 --- a/lib/console.c +++ b/lib/console.c @@ -35,13 +35,16 @@ static unsigned int console_loglevel(void) } #ifdef CONFIG_CONSOLE_BUFFER +struct printk_buffer *printk_buffer_addr(void) +{ + return global_vars()->printk_buffer; +} + void printk_buffer_move(void *newaddr, int newsize) { - struct printk_buffer **p; struct printk_buffer *oldbuf, *newbuf; int copylen; - p = bottom_of_stack(); - oldbuf = *p; + oldbuf = printk_buffer_addr(); newbuf = newaddr; newbuf->len = newsize; newbuf->readoffset = 0; @@ -68,17 +71,10 @@ void printk_buffer_move(void *newaddr, int newsize) &oldbuf->buffer[0], copylen); newbuf->writeoffset += copylen; } - *p = newbuf; + global_vars()->printk_buffer = newbuf; return; } -struct printk_buffer *printk_buffer_addr(void) -{ - struct printk_buffer **p; - p = bottom_of_stack(); - return *p; -} - void printk_buffer_init(void) { struct printk_buffer *buf = printk_buffer_addr();