On Fri, Feb 9, 2018 at 5:35 AM, Richard Henderson < richard.hender...@linaro.org> wrote:
> On 02/07/2018 05:28 PM, Michael Clark wrote: > > +++ b/hw/riscv/riscv_elf.c > > @@ -0,0 +1,244 @@ > > +/* > > + * elf.c - A simple package for manipulating symbol tables in elf > binaries. > > + * > > + * Taken from > > + * https://www.cs.cmu.edu/afs/cs.cmu.edu/academic/class/15213-f03/www/ > > + * ftrace/elf.c > > + * > > + */ > > +#include <stdio.h> > > +#include <stdlib.h> > > +#include <unistd.h> > > +#include <string.h> > > +#include <sys/stat.h> > > +#include <sys/types.h> > > +#include <sys/mman.h> > > +#include <errno.h> > > +#include <fcntl.h> > > +#include <glib.h> > > + > > +#include "hw/riscv/riscv_elf.h" > > + > > +/* > > + * elf_open - Map a binary into the address space and extract the > > + * locations of the static and dynamic symbol tables and their string > > + * tables. Return this information in a Elf object file handle that will > > + * be passed to all of the other elf functions. > > + */ > > +Elf_obj64 *elf_open64(const char *filename) > > +{ > > + int i, fd; > > + struct stat sbuf; > > + Elf_obj64 *ep; > > + Elf64_Shdr *shdr; > > + > > + ep = g_new(Elf_obj64, 1); > > + > > + /* Do some consistency checks on the binary */ > > + fd = open(filename, O_RDONLY); > > + if (fd == -1) { > > + fprintf(stderr, "Can't open \"%s\": %s\n", filename, > strerror(errno)); > > + exit(1); > > + } > > + if (fstat(fd, &sbuf) == -1) { > > + fprintf(stderr, "Can't stat \"%s\": %s\n", filename, > strerror(errno)); > > + exit(1); > > + } > > + if (sbuf.st_size < sizeof(Elf64_Ehdr)) { > > + fprintf(stderr, "\"%s\" is not an ELF binary object\n", > filename); > > + exit(1); > > + } > > + > > + /* It looks OK, so map the Elf binary into our address space */ > > + ep->mlen = sbuf.st_size; > > + ep->maddr = mmap(NULL, ep->mlen, PROT_READ, MAP_SHARED, fd, 0); > > + if (ep->maddr == (void *)-1) { > > + fprintf(stderr, "Can't mmap \"%s\": %s\n", filename, > strerror(errno)); > > + exit(1); > > + } > > + close(fd); > > + > > + /* The Elf binary begins with the Elf header */ > > + ep->ehdr = ep->maddr; > > + > > + /* check we have a 64-bit little-endian RISC-V ELF object */ > > + if (ep->ehdr->e_ident[EI_MAG0] != ELFMAG0 || > > + ep->ehdr->e_ident[EI_MAG1] != ELFMAG1 || > > + ep->ehdr->e_ident[EI_MAG2] != ELFMAG2 || > > + ep->ehdr->e_ident[EI_MAG3] != ELFMAG3 || > > + ep->ehdr->e_ident[EI_CLASS] != ELFCLASS64 || > > + ep->ehdr->e_ident[EI_DATA] != ELFDATA2LSB || > > + ep->ehdr->e_machine != EM_RISCV) > > + { > > + fprintf(stderr, "\"%s\" is not a 64-bit RISC-V ELF object\n", > filename); > > + exit(1); > > + } > > + > > + /* > > + * Find the static and dynamic symbol tables and their string > > + * tables in the the mapped binary. The sh_link field in symbol > > + * table section headers gives the section index of the string > > + * table for that symbol table. > > + */ > > + shdr = (Elf64_Shdr *)(ep->maddr + ep->ehdr->e_shoff); > > This duplicates, badly, existing code within include/hw/elf_ops.h. > > In particular, this fails to bswap these fields. As such, this code will > only > work on little-endian hosts. > There is enough information in the structures held in the syminfo table used by the disassembler however elf_ops.h currently throws away all symbols that are not STT_FUNC, and we are after STT_OBJECT symbols. We would need to add an option to load_elf to load the entire symbol table. Also, it runs qsort on the table by address, so we'd need to do a linear scan for the HTIF symbols by name. There are only two symbols we need: 'fromhost' and 'tohost'. /* We are only interested in function symbols. Throw everything else away. */ if (syms[i].st_shndx == SHN_UNDEF || syms[i].st_shndx >= SHN_LORESERVE || ELF_ST_TYPE(syms[i].st_info) != STT_FUNC) { nsyms--; if (i < nsyms) { syms[i] = syms[nsyms]; } continue; } It would be really nice if HTIF just specified registers in device-tree; alas it doesn't; and there is still quite a bit of code that depend on using these magic HTIF 'fromhost' and 'tohost' symbols. riscv-tests for one uses the HTIF mechanism and spike the official ISA simulator uses HTIF for IO.
