From 3879965dfda08a24e7d44ed76bbcc2f4a41df1fa Mon Sep 17 00:00:00 2001 From: Damien Le Moal Date: Wed, 9 Sep 2020 17:31:33 +0900 Subject: [PATCH] elf2flt: add riscv 64-bits support Add support for riscv 64bits ISA by defining the relocation types R_RISCV_32_PCREL, R_RISCV_ADD32, R_RISCV_SUB32, R_RISCV_32 and R_RISCV_64. riscv64 support also needs the __global_pointer$ symbol to be defined right after the relocation tables in the data section. Furthermore, the .got and .got.plt sections must be reversed. These 2 requirements are handled with runtime modifications of the default linker script using the append_sed() function. (1) For the .got.plt and .got sections order swap, append_sed() is used to rename "(.got.plt)" to "(.got.tmp)" and to rename "(.got)" to "(.got.plt)". A last call finalize the name swap by replacing "(.got.tmp)" with "(.got)" (2) For the global pointer synbol, a definition line starting with "RISCV_GP" is added. The "RISCV_GP" string is removed if the target CPU type is riscv64. The definition line is dropped for other CPU types. With these changes, buildroot/busybox builds and run on NOMMU systems with kernel 5.13. Tested on Canaan Kendryte K210 boards. This patch is based on earlier work by Christoph Hellwig . Signed-off-by: Damien Le Moal --- elf2flt.c | 23 +++++++++++++++++++++++ elf2flt.ld.in | 1 + ld-elf2flt.c | 16 ++++++++++++++++ 3 files changed, 40 insertions(+) diff --git a/elf2flt.c b/elf2flt.c index ea6b5a1..7100c20 100644 --- a/elf2flt.c +++ b/elf2flt.c @@ -81,6 +81,8 @@ const char *elf2flt_progname; #include #elif defined(TARGET_xtensa) #include +#elif defined(TARGET_riscv64) +#include #endif #if defined(__MINGW32__) @@ -123,6 +125,8 @@ const char *elf2flt_progname; #define ARCH "nios2" #elif defined(TARGET_xtensa) #define ARCH "xtensa" +#elif defined(TARGET_riscv64) +#define ARCH "riscv64" #else #error "Don't know how to support your CPU architecture??" #endif @@ -821,6 +825,16 @@ output_relocs ( goto good_32bit_resolved_reloc; default: goto bad_resolved_reloc; +#elif defined(TARGET_riscv64) + case R_RISCV_32_PCREL: + case R_RISCV_ADD32: + case R_RISCV_SUB32: + continue; + case R_RISCV_32: + case R_RISCV_64: + goto good_32bit_resolved_reloc; + default: + goto bad_resolved_reloc; #else default: /* The default is to assume that the @@ -1841,6 +1855,15 @@ int main(int argc, char *argv[]) if (!load_to_ram && !pfile) load_to_ram = 1; +#if defined(TARGET_riscv64) + /* + * riscv only supports loading text and data contiguously. + * So fail if load_to_ram is false. + */ + if (!load_to_ram) + fatal("Loading to RAM ('-r' option) is required"); +#endif + fname = argv[argc-1]; if (pfile) { diff --git a/elf2flt.ld.in b/elf2flt.ld.in index 0df999d..f1eed1f 100644 --- a/elf2flt.ld.in +++ b/elf2flt.ld.in @@ -109,6 +109,7 @@ W_RODAT: *(.gnu.linkonce.r*) . = ALIGN(0x20) ; LONG(-1) . = ALIGN(0x20) ; +RISCV_GP: __global_pointer$ = . + 0x800 ; R_RODAT: *(.rodata) R_RODAT: *(.rodata1) R_RODAT: *(.rodata.*) diff --git a/ld-elf2flt.c b/ld-elf2flt.c index 7cb02d5..1a503dd 100644 --- a/ld-elf2flt.c +++ b/ld-elf2flt.c @@ -324,6 +324,22 @@ static int do_final_link(void) append_option(&other_options, concat(got_offset, "=", buf, NULL)); } + if (streq(TARGET_CPU, "riscv64")) { + /* + * The .got section must come before the .got.plt section + * (gcc/ld bug ?). + */ + append_sed(&sed, "(.got.plt)", "(.got.tmp)"); + append_sed(&sed, "(.got.plt)", "(.got)"); + append_sed(&sed, "(.got.tmp)", "(.got.plt)"); + + /* The global pointer symbol is defined after the GOT. */ + append_sed(&sed, "^RISCV_GP:", ""); + } else { + /* Get rid of the global pointer definition. */ + append_sed(&sed, "^RISCV_GP:", NULL); + } + /* Locate the default linker script, if we don't have one provided. */ if (!linker_script) linker_script = concat(ldscriptpath, "/elf2flt.ld", NULL); -- 2.35.1