6d49446ebd
Enable selecting elf2flt for RISC-V 64-bits no MMU builds and add support for it in the form of an additional patch (upstream pull request https://github.com/uclinux-dev/elf2flt/pull/22). Also modify the package Makefile.in file to add the -fPIC option to the target CFLAGS for RISC-V 64-bits no MMU builds. This patch is based on initial work by Christoph Hellwig <hch@lst.de>. Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com> Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
138 lines
4.2 KiB
Diff
138 lines
4.2 KiB
Diff
From 1dea576eac4289602adc4a37f48c80330bf82e63 Mon Sep 17 00:00:00 2001
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From: Damien Le Moal <damien.lemoal@wdc.com>
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Date: Wed, 9 Sep 2020 17:31:33 +0900
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Subject: [PATCH] elf2flt: add riscv 64-bits support
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Add support for riscv 64bits ISA by defining the relocation types
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R_RISCV_32_PCREL, R_RISCV_ADD32, R_RISCV_SUB32, R_RISCV_32 and
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R_RISCV_64. riscv64 support also needs the __global_pointer$ symbol to
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be defined right after the relocation tables in the data section.
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Furthermore, the .got and .got.plt sections must be reversed. These 2
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requirements are handled with runtime modifications of the default
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linker script using the append_sed() function.
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(1) For the .got.plt and .got sections order swap, append_sed() is used
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to rename "(.got.plt)" to "(.got.tmp)" and to rename "(.got)" to
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"(.got.plt)". A last call finalize the name swap by replacing
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"(.got.tmp)" with "(.got)"
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(2) For the global pointer synbol, a definition line starting with
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"RISCV_GP" is added. The "RISCV_GP" string is removed if the target CPU
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type is riscv64. The definition line is dropped for other CPU types.
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With these changes, buildroot/busybox builds and run on NOMMU
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systems with kernel 5.13. Tested on Canaan Kendryte K210 boards.
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This patch is based on earlier work by Christoph Hellwig <hch@lst.de>.
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Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
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---
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elf2flt.c | 23 +++++++++++++++++++++++
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elf2flt.ld.in | 9 +++++----
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ld-elf2flt.c | 16 ++++++++++++++++
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3 files changed, 44 insertions(+), 4 deletions(-)
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diff --git a/elf2flt.c b/elf2flt.c
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index f87f1fc..dbce467 100644
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--- a/elf2flt.c
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+++ b/elf2flt.c
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@@ -80,6 +80,8 @@ const char *elf2flt_progname;
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#include <elf/v850.h>
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#elif defined(TARGET_xtensa)
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#include <elf/xtensa.h>
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+#elif defined(TARGET_riscv64)
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+#include <elf/riscv.h>
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#endif
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#if defined(__MINGW32__)
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@@ -122,6 +124,8 @@ const char *elf2flt_progname;
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#define ARCH "nios2"
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#elif defined(TARGET_xtensa)
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#define ARCH "xtensa"
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+#elif defined(TARGET_riscv64)
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+#define ARCH "riscv64"
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#else
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#error "Don't know how to support your CPU architecture??"
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#endif
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@@ -797,6 +801,16 @@ output_relocs (
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goto good_32bit_resolved_reloc;
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default:
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goto bad_resolved_reloc;
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+#elif defined(TARGET_riscv64)
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+ case R_RISCV_32_PCREL:
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+ case R_RISCV_ADD32:
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+ case R_RISCV_SUB32:
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+ continue;
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+ case R_RISCV_32:
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+ case R_RISCV_64:
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+ goto good_32bit_resolved_reloc;
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+ default:
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+ goto bad_resolved_reloc;
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#else
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default:
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/* The default is to assume that the
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@@ -1806,6 +1820,15 @@ int main(int argc, char *argv[])
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if (!load_to_ram && !pfile)
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load_to_ram = 1;
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+#if defined(TARGET_riscv64)
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+ /*
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+ * riscv only supports loading text and data contiguously.
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+ * So fail if load_to_ram is false.
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+ */
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+ if (!load_to_ram)
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+ fatal("Loading to RAM ('-r' option) is required");
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+#endif
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+
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fname = argv[argc-1];
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if (pfile) {
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diff --git a/elf2flt.ld.in b/elf2flt.ld.in
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index ec1fe6f..c0c44b8 100644
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--- a/elf2flt.ld.in
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+++ b/elf2flt.ld.in
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@@ -70,10 +70,11 @@ W_RODAT *(.gnu.linkonce.r*)
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. = ALIGN(0x20) ;
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LONG(-1)
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. = ALIGN(0x20) ;
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-R_RODAT *(.rodata)
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-R_RODAT *(.rodata1)
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-R_RODAT *(.rodata.*)
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-R_RODAT *(.gnu.linkonce.r*)
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+RISCV_GP: __global_pointer$ = . + 0x800 ;
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+R_RODAT *(.rodata)
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+R_RODAT *(.rodata1)
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+R_RODAT *(.rodata.*)
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+R_RODAT *(.gnu.linkonce.r*)
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*(.data)
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*(.data1)
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*(.data.*)
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diff --git a/ld-elf2flt.c b/ld-elf2flt.c
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index e5de506..31b565f 100644
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--- a/ld-elf2flt.c
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+++ b/ld-elf2flt.c
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@@ -324,6 +324,22 @@ static int do_final_link(void)
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append_option(&other_options, concat(got_offset, "=", buf, NULL));
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}
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+ if (streq(TARGET_CPU, "riscv64")) {
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+ /*
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+ * The .got section must come before the .got.plt section
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+ * (gcc/ld bug ?).
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+ */
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+ append_sed(&sed, "(.got.plt)", "(.got.tmp)");
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+ append_sed(&sed, "(.got.plt)", "(.got)");
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+ append_sed(&sed, "(.got.tmp)", "(.got.plt)");
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+
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+ /* The global pointer symbol is defined after the GOT. */
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+ append_sed(&sed, "^RISCV_GP:", "");
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+ } else {
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+ /* Get rid of the global pointer definition. */
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+ append_sed(&sed, "^RISCV_GP:", NULL);
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+ }
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+
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/* Locate the default linker script, if we don't have one provided. */
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if (!linker_script)
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linker_script = concat(ldscriptpath, "/elf2flt.ld", NULL);
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--
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2.31.1
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