ARCv2 has some configuration dependent registers (r30, r58, r59) which could be targetted by the compiler. To keep the ABI stable, these were unconditionally part of the glibc ABI (sysdeps/unix/sysv/linux/arc/sys/ucontext.h:mcontext_t) however we missed populating them (by saving/restoring them across signal handling).
This patch fixes the issue by - adding arcv2 ABI regs to kernel struct sigcontext - populating them during signal handling
Change to struct sigcontext might seem like a glibc ABI change (although it primarily uses ucontext_t:mcontext_t) but the fact is - it has only been extended (existing fields are not touched) - the old sigcontext was ABI incomplete to begin with anyways
Fixes: https://github.com/foss-for-synopsys-dwc-arc-processors/linux/issues/53 Cc: stable@vger.kernel.org Reported-by: Vladimir Isaev isaev@synopsys.com Signed-off-by: Vineet Gupta vgupta@synopsys.com --- arch/arc/include/uapi/asm/sigcontext.h | 1 + arch/arc/kernel/signal.c | 29 ++++++++++++++++++++++++++ 2 files changed, 30 insertions(+)
diff --git a/arch/arc/include/uapi/asm/sigcontext.h b/arch/arc/include/uapi/asm/sigcontext.h index 95f8a4380e11..7a5449dfcb29 100644 --- a/arch/arc/include/uapi/asm/sigcontext.h +++ b/arch/arc/include/uapi/asm/sigcontext.h @@ -18,6 +18,7 @@ */ struct sigcontext { struct user_regs_struct regs; + struct user_regs_arcv2 v2abi; };
#endif /* _ASM_ARC_SIGCONTEXT_H */ diff --git a/arch/arc/kernel/signal.c b/arch/arc/kernel/signal.c index b3ccb9e5ffe4..534b3d9bafc8 100644 --- a/arch/arc/kernel/signal.c +++ b/arch/arc/kernel/signal.c @@ -94,6 +94,21 @@ stash_usr_regs(struct rt_sigframe __user *sf, struct pt_regs *regs,
err = __copy_to_user(&(sf->uc.uc_mcontext.regs.scratch), &uregs.scratch, sizeof(sf->uc.uc_mcontext.regs.scratch)); + + if (is_isa_arcv2()) { + struct user_regs_arcv2 v2abi; + + v2abi.r30 = regs->r30; +#ifdef CONFIG_ARC_HAS_ACCL_REGS + v2abi.r58 = regs->r58; + v2abi.r59 = regs->r59; +#else + v2abi.r58 = v2abi.r59 = 0; +#endif + err |= __copy_to_user(&(sf->uc.uc_mcontext.v2abi), &v2abi, + sizeof(sf->uc.uc_mcontext.v2abi)); + } + err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(sigset_t));
return err ? -EFAULT : 0; @@ -109,6 +124,20 @@ static int restore_usr_regs(struct pt_regs *regs, struct rt_sigframe __user *sf) err |= __copy_from_user(&uregs.scratch, &(sf->uc.uc_mcontext.regs.scratch), sizeof(sf->uc.uc_mcontext.regs.scratch)); + + if (is_isa_arcv2()) { + struct user_regs_arcv2 v2abi; + + err |= __copy_from_user(&v2abi, &(sf->uc.uc_mcontext.v2abi), + sizeof(sf->uc.uc_mcontext.v2abi)); + + regs->r30 = v2abi.r30; +#ifdef CONFIG_ARC_HAS_ACCL_REGS + regs->r58 = v2abi.r58; + regs->r59 = v2abi.r59; +#endif + } + if (err) return -EFAULT;