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Clear bss at runtime like Nintendo actually does

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This commit is contained in:
TuxSH 2018-02-28 22:29:17 +01:00
parent 303774aeb7
commit 0a89831193
2 changed files with 32 additions and 17 deletions
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31
exosphere/linker.ld
View file

@ -68,8 +68,14 @@ SECTIONS
build/package2.o(.rodata*)
build/package2.o(.data*)
. = ALIGN(8);
} >pk2ldr AT>fake
.pk2ldr.bss :
{
. = ALIGN(8);
__pk2ldr_bss_start__ = ABSOLUTE(.);
build/package2.o(.bss*)
. = ALIGN(16);
. = ALIGN(8);
__pk2ldr_end__ = ABSOLUTE(.);
} >pk2ldr AT>fake
@ -79,7 +85,7 @@ SECTIONS
__vectors_lma__ = LOADADDR(.vectors);
__vectors_start__ = ABSOLUTE(.);
KEEP (*(.vectors*))
. = ALIGN(16);
. = ALIGN(8);
__vectors_end__ = ABSOLUTE(.);
} >evt AT>fake
@ -178,16 +184,6 @@ SECTIONS
*(.data .data.* .gnu.linkonce.d.*)
CONSTRUCTORS
. = ALIGN(8);
/*
We're too lazy to clear BSS so we integrate it into .data.
Nintendo does the same for this main segment's BSS.
*/
__bss_start__ = ABSOLUTE(.);
*(.dynbss)
*(.bss .bss.* .gnu.linkonce.b.*)
*(COMMON)
. = ALIGN(8);
__bss_end__ = ABSOLUTE(.);
} >main AT>fake
@ -209,6 +205,17 @@ SECTIONS
.dynstr : { *(.dynstr) } >main AT>fake
.rela.dyn : { *(.rela.*); __main_end__ = ABSOLUTE(.);} >main AT>fake
.bss :
{
. = ALIGN(8);
__main_bss_start__ = ABSOLUTE(.);
*(.dynbss)
*(.bss .bss.* .gnu.linkonce.b.*)
*(COMMON)
. = ALIGN(8);
__main_end__ = ABSOLUTE(.);
} >main AT>fake
__end__ = ABSOLUTE(.) ;
. = ALIGN(0x1000);

18
exosphere/src/coldboot_init.c
View file

@ -1,3 +1,4 @@
#include <string.h>
#include "utils.h"
#include "mmu.h"
#include "memory_map.h"
@ -5,8 +6,8 @@
extern const uint8_t __start_cold[];
extern const uint8_t __warmboot_crt0_start__[], __warmboot_crt0_end__[], __warmboot_crt0_lma__[];
extern const uint8_t __main_start__[], __main_end__[], __main_lma__[];
extern const uint8_t __pk2ldr_start__[], __pk2ldr_end__[], __pk2ldr_lma__[];
extern const uint8_t __main_start__[], __main_bss_start__[], __main_end__[], __main_lma__[];
extern const uint8_t __pk2ldr_start__[], __pk2ldr_bss_start__[], __pk2ldr_end__[], __pk2ldr_lma__[];
extern const uint8_t __vectors_start__[], __vectors_end__[], __vectors_lma__[];
/* warmboot_init.c */
@ -120,10 +121,17 @@ __attribute__((target("cmodel=large"), noinline)) static void copy_other_section
copy_lma_to_vma(__vectors_start__, __vectors_lma__, __vectors_end__ - __vectors_start__);
}
__attribute__((target("cmodel=large"), noinline)) static void clear_bss(void) {
memset((void *)__pk2ldr_bss_start__, 0, __pk2ldr_end__ - __pk2ldr_bss_start__);
memset((void *)__main_bss_start__, 0, __main_end__ - __main_bss_start__);
}
void coldboot_init(void) {
/* TODO: Set NX BOOTLOADER clock time field */
copy_warmboot_crt0();
/* At this point, we can (and will) access functions located in .warm_crt0 */
/* TODO: initialize DMA controllers, etc. */
configure_ttbls();
copy_other_sections();
@ -131,7 +139,7 @@ void coldboot_init(void) {
flush_dcache_all_tzram_pa();
invalidate_icache_all_inner_shareable_tzram_pa();
/* At this point we can access all the mapped segments */
/* TODO: zero-initialize the cpu context */
/* Nintendo clears the (emtpy) pk2ldr's BSS section here , but we embed it 0-filled in the binary */
/* At this point we can access all the mapped segments (all other functions, data...) normally */
clear_bss();
}