Define HAVE_ELF_CORE_DUMP and target_elf_gregset_t in target_elf.h,
mirroring struct user_regs_struct: pc followed by x1 (ra) through
x31 (t6). Implement elf_core_copy_regs() in elfload.c to populate
the gregset from CPURISCVState.
Without this, bprm->core_dump is NULL for RISC-V targets. When a
guest signal goes unhandled, dump_core_and_abort() skips the core
write and falls through to die_with_signal(), which re-raises the
signal to the host. The host kernel then writes an x86-64 core file
for the qemu-riscv64 process instead of a RISC-V guest core.
Signed-off-by: Matt Turner <mattst88@gmail.com>
Signed-off-by: Helge Deller <deller@gmx.de>
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