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nios2: enable use of global pointer indirect addressing

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needs to be 0x8000 after .sdata and .sbss sections since
register offsets are 16-bit signed values.

Change-Id: Ia7486d32af81e54a6ebac6be7ec308dfdeafe79e
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
This commit is contained in:
Andrew Boie 2016-06-30 11:57:51 -07:00 • committed by Inaky Perez-Gonzalez
commit fca3591bce
3 changed files with 43 additions and 27 deletions
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4
arch/nios2/Makefile
View file

@ -1,9 +1,5 @@
-include $(srctree)/arch/$(ARCH)/soc/$(SOC_PATH)/Makefile
# FIXME: Disable use of global pointer for now, this isn't properly set up
# in our linker script.
arch_cflags := $(call cc-option,-G0)
# Put functions and data in their own binary sections so that ld can
# garbage collect them
arch_cflags += $(call cc-option,-ffunction-sections) \

6
arch/nios2/core/crt0.S
View file

@ -145,9 +145,9 @@ SECTION_FUNC(TEXT, __start)
/* Align the stack pointer */
and sp, sp, r1
/* TODO Setup the global pointer
* ZEP-272
*/
/* Initialize global pointer with the linker variable we set */
movhi gp, %hi(_gp)
ori gp, gp, %lo(_gp)
/* TODO if shadow register sets enabled, interate through them to set
* up. Need to clear r0, write gp, set the execption stack pointer

60
include/arch/nios2/linker.ld
View file

@ -182,29 +182,11 @@ SECTIONS
} GROUP_LINK_IN(RAMABLE_REGION)
#endif
SECTION_PROLOGUE(_DATA_SECTION_NAME,,)
SECTION_PROLOGUE(initlevel, (OPTIONAL),)
{
#ifndef CONFIG_XIP
_image_ram_start = .;
#endif
*(.data)
*(".data.*")
KEEP(*(.isr_irq*))
/* sections for IRQ0-9 */
KEEP(*(SORT(.gnu.linkonce.isr_irq[0-9])))
/* sections for IRQ10-99 */
KEEP(*(SORT(.gnu.linkonce.isr_irq[0-9][0-9])))
/* sections for IRQ100-999 */
KEEP(*(SORT(.gnu.linkonce.isr_irq[0-9][0-9][0-9])))
} GROUP_LINK_IN(RAMABLE_REGION)
SECTION_PROLOGUE(initlevel, (OPTIONAL),)
{
DEVICE_INIT_SECTIONS()
} GROUP_LINK_IN(RAMABLE_REGION)
@ -255,6 +237,43 @@ SECTIONS
_k_event_list_end = .;
} GROUP_LINK_IN(RAMABLE_REGION)
SECTION_PROLOGUE(_DATA_SECTION_NAME,,)
{
KEEP(*(.isr_irq*))
/* sections for IRQ0-9 */
KEEP(*(SORT(.gnu.linkonce.isr_irq[0-9])))
/* sections for IRQ10-99 */
KEEP(*(SORT(.gnu.linkonce.isr_irq[0-9][0-9])))
/* sections for IRQ100-999 */
KEEP(*(SORT(.gnu.linkonce.isr_irq[0-9][0-9][0-9])))
*(.data)
*(".data.*")
/* the Nios2 architecture only has 16-bit signed immediate offsets in
* the instructions, so accessing a general address requires typically
* three instructions – basically, two for the two halves of the 32-bit
* address, and one to merge them – but if we can put the most commonly
* accessed globals in a special 64K span of memory addressed by the GP
* register, then we can access those values in a single instruction,
* saving both codespace and runtime.
*
* Since these immediate offsets are signed, place gp 0x8000 past the
* beginning of .sdata so that we can use both positive and negative
* offsets.
*/
_gp = ABSOLUTE(. + 0x8000);
PROVIDE(gp = _gp);
*(.sdata .sdata.* .gnu.linkonce.s.*)
*(.sdata2 .sdata2.* .gnu.linkonce.s2.*)
} GROUP_LINK_IN(RAMABLE_REGION)
__data_ram_end = .;
SECTION_PROLOGUE(_BSS_SECTION_NAME,(NOLOAD),)
@ -265,8 +284,9 @@ SECTIONS
*/
. = ALIGN(4);
__bss_start = .;
*(.bss)
*(.sbss)
*(".sbss.*")
*(.bss)
*(".bss.*")
COMMON_SYMBOLS
/*