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switched to a real linker script

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master
Anton Lydike 3 years ago
parent b058330a16
commit 962b209f30
2 changed files with 238 additions and 34 deletions
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8
kinclude/boot.S
Unescape Escape View File

@ -33,12 +33,12 @@ _start:
.option norelax .option norelax
// init sp and gp // init sp and gp
la sp, stack_top la sp, stack_top
la gp, __global_pointer$ la gp, _gp
.option pop .option pop
// clear kernel bss section // clear kernel bss section
mv a0, zero mv a0, zero
la a1, __bss_start la a1, _bss_start
la a2, __bss_end la a2, _bss_end
jal memset jal memset
// jump to init // jump to init
@ -97,7 +97,7 @@ trap_vector:
.option push .option push
.option norelax .option norelax
la sp, stack_top la sp, stack_top
la gp, __global_pointer$ la gp, _gp
.option pop .option pop
jal trap_handle jal trap_handle

264
linker.ld
Unescape Escape View File

@ -1,32 +1,236 @@
OUTPUT_ARCH("riscv") /*======================================================================*/
ENTRY(_start) /* EMBARK linker script, based on the Default maven linker script */
/*======================================================================*/
/* for the original file, see:
https://github.com/pulp-platform/pulp-riscv-gnu-toolchain/blob/49dea1915979fdf91eb2ad4a8873e4cd88a6b811/riscv.ld */
/* I modified the original file minimally,
/* This is the default linker script for maven. It is based off of the
mips idt32.ld linker script. I have added many more comments and
tried to clean things up a bit. For more information about standard
MIPS sections see Section 9.5 of "See MIPS Run Linux" by Dominic
Sweetman. For more generic information about the init, fini, ctors,
and dtors sections see the paper titled "ELF From the Programmers
Perspective" by Hongiu Lu. */
/*----------------------------------------------------------------------*/
/* Setup */
/*----------------------------------------------------------------------*/
/* The OUTPUT_ARCH command specifies the machine architecture where the
argument is one of the names used in the BFD library. More
specifically one of the entires in bfd/cpu-mips.c */
OUTPUT_ARCH( "riscv" )
/* The ENTRY command specifies the entry point (ie. first instruction to
execute). The symbol _start is defined in crt0.S */
ENTRY( _start )
/* The GROUP command is special since the listed archives will be
searched repeatedly until there are no new undefined references. We
need this since -lc depends on -lgloss and -lgloss depends on -lc. I
thought gcc would automatically include -lgcc when needed, but
idt32.ld includes it explicitly here and I was seeing link errors
without it. */
GROUP( -lc -lgloss -lgcc )
/*----------------------------------------------------------------------*/
/* Sections */
/*----------------------------------------------------------------------*/
/* This is where we specify how the input sections map to output
sections. The .= commands set the location counter, and the
sections are inserted in increasing address order according to the
location counter. The following statement will take all of the .bar
input sections and reloate them into the .foo output section which
starts at address 0x1000.
. = 0.x1000;
.foo : { *(.bar) }
If we wrap an input specification with a KEEP command then it
prevents it from being eliminted during "link-time garbage
collection". I'm not sure what this is, so I just followed what was
done in idt32.ld.
We can also set a global external symbol to a specific address in the
output binary with this syntax:
_etext = .;
PROVIDE( etext = . );
This will set the global symbol _ftext to the current location. If we
wrap this in a PROVIDE commad, the symbol will only be set if it is
not defined. We do this with symbols which don't begin with an
underscore since technically in ansi C someone might have a function
with the same name (eg. etext).
If we need to label the beginning of a section we need to make sure
that the linker doesn't insert an orphan section inbetween where we
set the symbol and the actual begining of the section. We can do that
by assigning the location dot to itself.
. = .
_ftext = .;
.text :
{ }
*/
SECTIONS SECTIONS
{ {
/* start at an address > 12bit to ensure all addresses are loaded using auipc+addi instead of only addi (which is not relocatable)*/
. = 0xffffff; /*--------------------------------------------------------------------*/
.text : /* Code and read-only segment */
{ /*--------------------------------------------------------------------*/
*(.text._start)
*(.text) /* Begining of code and text segment */
} . = 0x00010000;
.sdata : _ftext = .;
{ PROVIDE( eprol = . );
__global_pointer$ = . + 0x800;
*(.srodata.cst16) *(.srodata.cst8) *(.srodata.cst4) *(.srodata.cst2) *(.srodata .srodata.*) /* text: Program code section */
*(.sdata .sdata.* .gnu.linkonce.s.*) .text :
} {
_edata = .; PROVIDE (edata = .); *(.text._start)
. = .; *(.text)
__bss_start = .; *(.text.*)
.sbss : *(.gnu.linkonce.t.*)
{ }
*(.dynsbss)
*(.sbss .sbss.* .gnu.linkonce.sb.*) /* init: Code to execute before main (called by crt0.S) */
*(.scommon) .init :
} {
__bss_end = .; KEEP( *(.init) )
.stack : }
{
*(.stack) /* fini: Code to execute after main (called by crt0.S) */
} .fini :
} {
KEEP( *(.fini) )
}
/* End of code and read-only segment */
PROVIDE( etext = . );
_etext = .;
/*--------------------------------------------------------------------*/
/* Global constructor/destructor segement */
/*--------------------------------------------------------------------*/
.preinit_array :
{
PROVIDE_HIDDEN (__preinit_array_start = .);
KEEP (*(.preinit_array))
PROVIDE_HIDDEN (__preinit_array_end = .);
}
.init_array :
{
PROVIDE_HIDDEN (__init_array_start = .);
KEEP (*(SORT(.init_array.*)))
KEEP (*(.init_array ))
PROVIDE_HIDDEN (__init_array_end = .);
}
.fini_array :
{
PROVIDE_HIDDEN (__fini_array_start = .);
KEEP (*(SORT(.fini_array.*)))
KEEP (*(.fini_array ))
PROVIDE_HIDDEN (__fini_array_end = .);
}
/* rodata: Read-only data */
.rodata :
{
*(.rdata)
*(.rodata)
*(.rodata.*)
*(.gnu.linkonce.r.*)
}
/*--------------------------------------------------------------------*/
/* Other misc gcc segments (this was in idt32.ld) */
/*--------------------------------------------------------------------*/
/* I am not quite sure about these sections but it seems they are for
C++ exception handling. I think .jcr is for "Java Class
Registration" but it seems to end up in C++ binaries as well. */
.eh_frame_hdr : { *(.eh_frame_hdr) }
.eh_frame : { KEEP( *(.eh_frame) ) }
.gcc_except_table : { *(.gcc_except_table) }
.jcr : { KEEP (*(.jcr)) }
/*--------------------------------------------------------------------*/
/* Initialized data segment */
/*--------------------------------------------------------------------*/
/* Start of initialized data segment */
. = ALIGN(16);
_fdata = .;
/* data: Writable data */
.data :
{
*(.data)
*(.data.*)
*(.gnu.linkonce.d.*)
}
/* End of initialized data segment */
PROVIDE( edata = . );
_edata = .;
/* Have _gp point to middle of sdata/sbss to maximize displacement range */
. = ALIGN(16);
_gp = . + 0x800;
/* Writable small data segment */
.sdata :
{
*(.sdata)
*(.sdata.*)
*(.srodata.*)
*(.gnu.linkonce.s.*)
}
/*--------------------------------------------------------------------*/
/* Uninitialized data segment */
/*--------------------------------------------------------------------*/
/* Start of uninitialized data segment */
. = ALIGN(8);
_fbss = .;
_bss_start = .;
/* Writable uninitialized small data segment */
.sbss :
{
*(.sbss)
*(.sbss.*)
*(.gnu.linkonce.sb.*)
}
/* bss: Uninitialized writeable data section */
. = .;
.bss :
{
*(.bss)
*(.bss.*)
*(.gnu.linkonce.b.*)
*(COMMON)
}
_bss_end = .;
.stack :
{
*(.stack)
}
/* End of uninitialized data segment (used by syscalls.c for heap) */
PROVIDE( end = . );
_end = ALIGN(8);
}

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