On Thu, Apr 5, 2018 at 12:44 AM, Laurent Vivier wrote:
> Le 02/03/2018 à 14:51, Michael Clark a écrit :
> > Implementation of linux user emulation for RISC-V.
> >
> > Reviewed-by: Richard Henderson
> > Signed-off-by: Sagar Karandikar
> > Signed-off-by: Michael Clark
> > ---
> > linux-user/elfload.c | 22 +++
> > linux-user/main.c | 99 +
> > linux-user/riscv/syscall_nr.h | 287 ++
>
> > linux-user/riscv/target_cpu.h | 18 +++
> > linux-user/riscv/target_elf.h | 14 ++
> > linux-user/riscv/target_signal.h | 23 +++
> > linux-user/riscv/target_structs.h | 46 ++
> > linux-user/riscv/target_syscall.h | 56
> > linux-user/riscv/termbits.h | 222 +
> > linux-user/signal.c | 203 ++-
> > linux-user/syscall.c | 2 +
> > linux-user/syscall_defs.h | 13 +-
> > target/riscv/cpu_user.h | 13 ++
> > 13 files changed, 1012 insertions(+), 6 deletions(-)
> > create mode 100644 linux-user/riscv/syscall_nr.h
> > create mode 100644 linux-user/riscv/target_cpu.h
> > create mode 100644 linux-user/riscv/target_elf.h
> > create mode 100644 linux-user/riscv/target_signal.h
> > create mode 100644 linux-user/riscv/target_structs.h
> > create mode 100644 linux-user/riscv/target_syscall.h
> > create mode 100644 linux-user/riscv/termbits.h
> > create mode 100644 target/riscv/cpu_user.h
> >
> ...
> > diff --git a/linux-user/signal.c b/linux-user/signal.c
> > index 9a380b9..4d3f244 100644
> > --- a/linux-user/signal.c
> > +++ b/linux-user/signal.c
> ...
> > +static abi_ulong get_sigframe(struct target_sigaction *ka,
> > + CPURISCVState *regs, size_t framesize)
> > +{
> > +abi_ulong sp = regs->gpr[xSP];
> > +int onsigstack = on_sig_stack(sp);
> > +
> > +/* redzone */
> > +/* This is the X/Open sanctioned signal stack switching. */
> > +if ((ka->sa_flags & TARGET_SA_ONSTACK) != 0 && !onsigstack) {
> > +sp = target_sigaltstack_used.ss_sp + target_sigaltstack_used.ss_
> size;
> > +}
> > +
> > +sp -= framesize;
> > +sp &= ~3UL; /* align sp on 4-byte boundary */
>
> kernel aligns using 0xf. Why do you use a different alignment?
Thanks for reviewing this! This looks like a bug!
I'm raising this as an issue on the riscv-qemu tracker so that its easier
than searching through the mail archive:
- https://github.com/riscv/riscv-qemu/issues/129
> +
> > +/* If we are on the alternate signal stack and would overflow it,
> don't.
> > + Return an always-bogus address instead so we will die with
> SIGSEGV. */
> > +if (onsigstack && !likely(on_sig_stack(sp))) {
> > +return -1L;
> > +}
> > +
> > +return sp;
> > +}
> Other question why don't you use the same logic as in kernel?
>
> 1- check for signal stack overflow
> 2- check for X/Open sanctioned signal stack switching
>
> static inline void __user *get_sigframe(struct ksignal *ksig,
> struct pt_regs *regs, size_t framesize)
> {
> unsigned long sp;
> /* Default to using normal stack */
> sp = regs->sp;
>
> /*
> * If we are on the alternate signal stack and would overflow
> it, don't.
> * Return an always-bogus address instead so we will die with
> SIGSEGV.
> */
> if (on_sig_stack(sp) && !likely(on_sig_stack(sp - framesize)))
> return (void __user __force *)(-1UL);
>
> /* This is the X/Open sanctioned signal stack switching. */
> sp = sigsp(sp, ksig) - framesize;
>
> /* Align the stack frame. */
> sp &= ~0xfUL;
>
> return (void __user *)sp;
> }
>
> Thanks,
> Laurent
>
