Started with the aarch64 support and modified it for RISC-V. The flattened structure support hasn't been written yet, but the rest of it should be correct for the LP64D ABI. We have potentially 6 different ABIs to support, so this requires checking elf header flags in riscv_init when setting the hook.
Signed-off-by: Jim Wilson <j...@sifive.com> --- backends/ChangeLog | 8 ++ backends/Makefile.am | 2 +- backends/riscv_init.c | 10 +- backends/riscv_retval.c | 251 ++++++++++++++++++++++++++++++++++++++++ 4 files changed, 269 insertions(+), 2 deletions(-) create mode 100644 backends/riscv_retval.c diff --git a/backends/ChangeLog b/backends/ChangeLog index c8234072..637aa8c2 100644 --- a/backends/ChangeLog +++ b/backends/ChangeLog @@ -1,5 +1,13 @@ 2018-12-27 Jim Wilson <j...@sifive.com> + * Makefile.am (riscv_SRCS): Add riscv_retval.c. + * riscv_init.c: Include libelfP.h. + (riscv_return_value_location_lp64d): Declare. + (riscv_init): Delete unused attribute from elf parameter. Register + riscv_return_value_location_lp64d hook if 64-bit ELF and 64-bit FP + registers. + * riscv_retval.c: New file. + * riscv_corenote.c (prstatus_regs): Change offset from 1 to 8. (PRSTATUS_REGSET_ITEMS): New. diff --git a/backends/Makefile.am b/backends/Makefile.am index 9d340425..fedeb93a 100644 --- a/backends/Makefile.am +++ b/backends/Makefile.am @@ -132,7 +132,7 @@ libebl_bpf_pic_a_SOURCES = $(bpf_SRCS) am_libebl_bpf_pic_a_OBJECTS = $(bpf_SRCS:.c=.os) riscv_SRCS = riscv_init.c riscv_symbol.c riscv_cfi.c riscv_regs.c \ - riscv_initreg.c riscv_corenote.c + riscv_initreg.c riscv_corenote.c riscv_retval.c libebl_riscv_pic_a_SOURCES = $(riscv_SRCS) am_libebl_riscv_pic_a_OBJECTS = $(riscv_SRCS:.c=.os) diff --git a/backends/riscv_init.c b/backends/riscv_init.c index 8b7ce8b5..ecee2910 100644 --- a/backends/riscv_init.c +++ b/backends/riscv_init.c @@ -33,12 +33,16 @@ #define RELOC_PREFIX R_RISCV_ #include "libebl_CPU.h" +#include "libelfP.h" + /* This defines the common reloc hooks based on riscv_reloc.def. */ #include "common-reloc.c" +extern __typeof (EBLHOOK (return_value_location)) + riscv_return_value_location_lp64d attribute_hidden; const char * -riscv_init (Elf *elf __attribute__ ((unused)), +riscv_init (Elf *elf, GElf_Half machine __attribute__ ((unused)), Ebl *eh, size_t ehlen) @@ -59,6 +63,10 @@ riscv_init (Elf *elf __attribute__ ((unused)), HOOK (eh, machine_flag_check); HOOK (eh, set_initial_registers_tid); HOOK (eh, core_note); + if (eh->class == ELFCLASS64 + && ((elf->state.elf64.ehdr->e_flags & EF_RISCV_FLOAT_ABI) + == EF_RISCV_FLOAT_ABI_DOUBLE)) + eh->return_value_location = riscv_return_value_location_lp64d; return MODVERSION; } diff --git a/backends/riscv_retval.c b/backends/riscv_retval.c new file mode 100644 index 00000000..35b6010b --- /dev/null +++ b/backends/riscv_retval.c @@ -0,0 +1,251 @@ +/* Function return value location for Linux/RISC-V ABI. + Copyright (C) 2018 Sifive, Inc. + Copyright (C) 2013 Red Hat, Inc. + This file is part of elfutils. + + This file is free software; you can redistribute it and/or modify + it under the terms of either + + * the GNU Lesser General Public License as published by the Free + Software Foundation; either version 3 of the License, or (at + your option) any later version + + or + + * the GNU General Public License as published by the Free + Software Foundation; either version 2 of the License, or (at + your option) any later version + + or both in parallel, as here. + + elfutils is distributed in the hope that it will be useful, but + WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + General Public License for more details. + + You should have received copies of the GNU General Public License and + the GNU Lesser General Public License along with this program. If + not, see <http://www.gnu.org/licenses/>. */ + +#ifdef HAVE_CONFIG_H +# include <config.h> +#endif + +#include <stdio.h> +#include <inttypes.h> + +#include <assert.h> +#include <dwarf.h> + +#define BACKEND riscv_ +#include "libebl_CPU.h" + +static int +dwarf_bytesize_aux (Dwarf_Die *die, Dwarf_Word *sizep) +{ + int bits; + if (((bits = 8 * dwarf_bytesize (die)) < 0 + && (bits = dwarf_bitsize (die)) < 0) + || bits % 8 != 0) + return -1; + + *sizep = bits / 8; + return 0; +} + +static int +pass_in_gpr_lp64 (const Dwarf_Op **locp, Dwarf_Word size) +{ + static const Dwarf_Op loc[] = + { + { .atom = DW_OP_reg10 }, { .atom = DW_OP_piece, .number = 8 }, + { .atom = DW_OP_reg11 }, { .atom = DW_OP_piece, .number = 8 } + }; + + *locp = loc; + return size <= 8 ? 1 : 4; +} + +static int +pass_by_ref (const Dwarf_Op **locp) +{ + static const Dwarf_Op loc[] = { { .atom = DW_OP_breg10 } }; + + *locp = loc; + return 1; +} + +static int +pass_in_fpr_lp64f (const Dwarf_Op **locp, Dwarf_Word size) +{ + static const Dwarf_Op loc[] = + { + { .atom = DW_OP_regx, .number = 42 }, + { .atom = DW_OP_piece, .number = 4 }, + { .atom = DW_OP_regx, .number = 43 }, + { .atom = DW_OP_piece, .number = 4 } + }; + + *locp = loc; + return size <= 4 ? 1 : 4; +} + +static int +pass_in_fpr_lp64d (const Dwarf_Op **locp, Dwarf_Word size) +{ + static const Dwarf_Op loc[] = + { + { .atom = DW_OP_regx, .number = 42 }, + { .atom = DW_OP_piece, .number = 8 }, + { .atom = DW_OP_regx, .number = 43 }, + { .atom = DW_OP_piece, .number = 8 } + }; + + *locp = loc; + return size <= 8 ? 1 : 4; +} + +static int +flatten_aggregate_arg (Dwarf_Die *typedie __attribute__ ((unused)), + Dwarf_Die *arg0 __attribute__ ((unused)), + Dwarf_Die *arg1 __attribute__ ((unused))) +{ + /* ??? */ + return 1; +} + +static int +pass_by_flattened_arg (const Dwarf_Op **locp __attribute__ ((unused)), + Dwarf_Word size __attribute__ ((unused)), + Dwarf_Die *arg0 __attribute__ ((unused)), + Dwarf_Die *arg1 __attribute__ ((unused))) +{ + /* ??? */ + return -2; +} + +int +riscv_return_value_location_lp64d (Dwarf_Die *functypedie, + const Dwarf_Op **locp) +{ + /* Start with the function's type, and get the DW_AT_type attribute, + which is the type of the return value. */ + Dwarf_Die typedie; + int tag = dwarf_peeled_die_type (functypedie, &typedie); + if (tag <= 0) + return tag; + + Dwarf_Word size = (Dwarf_Word)-1; + + /* If the argument type is a Composite Type that is larger than 16 + bytes, then the argument is copied to memory allocated by the + caller and the argument is replaced by a pointer to the copy. */ + if (tag == DW_TAG_structure_type || tag == DW_TAG_union_type + || tag == DW_TAG_class_type || tag == DW_TAG_array_type) + { + Dwarf_Die arg0, arg1; + + if (dwarf_aggregate_size (&typedie, &size) < 0) + return -1; + /* A struct containing just one floating-point real is passed as though + it were a standalone floating-point real. A struct containing two + floating-point reals is passed in two floating-point registers, if + neither is more than FLEN bits wide. A struct containing just one + complex floating-point number is passed as though it were a struct + containing two floating-point reals. A struct containing one + floating-point real and one integer (or bitfield), in either order, + is passed in a floating-point register and an integer register, + provided the floating-point real is no more than FLEN bits wide and + the integer is no more than XLEN bits wide. */ + if (tag == DW_TAG_structure_type + && flatten_aggregate_arg (&typedie, &arg0, &arg1)) + return pass_by_flattened_arg (locp, size, &arg0, &arg1); + /* Aggregates larger than 2*XLEN bits are passed by reference. */ + else if (size > 16) + return pass_by_ref (locp); + /* Aggregates whose total size is no more than XLEN bits are passed in + a register. Aggregates whose total size is no more than 2*XLEN bits + are passed in a pair of registers. */ + else + return pass_in_gpr_lp64 (locp, size); + } + + if (tag == DW_TAG_base_type + || tag == DW_TAG_pointer_type || tag == DW_TAG_ptr_to_member_type) + { + if (dwarf_bytesize_aux (&typedie, &size) < 0) + { + if (tag == DW_TAG_pointer_type || tag == DW_TAG_ptr_to_member_type) + size = 8; + else + return -1; + } + + Dwarf_Attribute attr_mem; + if (tag == DW_TAG_base_type) + { + Dwarf_Word encoding; + if (dwarf_formudata (dwarf_attr_integrate (&typedie, DW_AT_encoding, + &attr_mem), + &encoding) != 0) + return -1; + + switch (encoding) + { + case DW_ATE_boolean: + case DW_ATE_signed: + case DW_ATE_unsigned: + case DW_ATE_unsigned_char: + case DW_ATE_signed_char: + /* Scalars that are at most XLEN bits wide are passed in a single + argument register. Scalars that are 2*XLEN bits wide are + passed in a pair of argument registers. Scalars wider than + 2*XLEN are passed by reference; there are none for LP64D. */ + return pass_in_gpr_lp64 (locp, size); + + case DW_ATE_float: + /* A real floating-point argument is passed in a floating-point + argument register if it is no more than FLEN bits wide, + otherwise it is passed according to the integer calling + convention. */ + switch (size) + { + case 4: /* single */ + case 8: /* double */ + return pass_in_fpr_lp64d (locp, size); + + case 16: /* quad */ + return pass_in_gpr_lp64 (locp, size); + + default: + return -2; + } + + case DW_ATE_complex_float: + /* A complex floating-point number is passed as though it were a + struct containing two floating-point reals. */ + switch (size) + { + case 8: /* float _Complex */ + return pass_in_fpr_lp64f (locp, size); + + case 16: /* double _Complex */ + return pass_in_fpr_lp64d (locp, size); + + case 32: /* long double _Complex */ + return pass_by_ref (locp); + + default: + return -2; + } + } + + return -2; + } + else + return pass_in_gpr_lp64 (locp, size); + } + + *locp = NULL; + return 0; +} -- 2.19.2