Commit 96f1b001 authored by Vineet Gupta's avatar Vineet Gupta
Browse files

ARCv2: save ABI registers across signal handling 

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>
Tested-by: default avatarkernel test robot <lkp@intel.com>
Reported-by: default avatarVladimir Isaev <isaev@synopsys.com>
Signed-off-by: default avatarVineet Gupta <vgupta@synopsys.com>
parent d07f6ca9

arch/arc/include/uapi/asm/sigcontext.h

+1 −0
Original line number Diff line number Diff line
@@ -18,6 +18,7 @@ 
 */

struct sigcontext {

	struct user_regs_struct regs;

	struct user_regs_arcv2 v2abi;

};



#endif /* _ASM_ARC_SIGCONTEXT_H */

arch/arc/kernel/signal.c

+43 −0
Original line number Diff line number Diff line
@@ -61,6 +61,41 @@ struct rt_sigframe { 
	unsigned int sigret_magic;

};



static int save_arcv2_regs(struct sigcontext *mctx, struct pt_regs *regs)

{

	int err = 0;

#ifndef CONFIG_ISA_ARCOMPACT

	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(&mctx->v2abi, &v2abi, sizeof(v2abi));

#endif

	return err;

}



static int restore_arcv2_regs(struct sigcontext *mctx, struct pt_regs *regs)

{

	int err = 0;

#ifndef CONFIG_ISA_ARCOMPACT

	struct user_regs_arcv2 v2abi;



	err = __copy_from_user(&v2abi, &mctx->v2abi, sizeof(v2abi));



	regs->r30 = v2abi.r30;

#ifdef CONFIG_ARC_HAS_ACCL_REGS

	regs->r58 = v2abi.r58;

	regs->r59 = v2abi.r59;

#endif

#endif

	return err;

}



static int

stash_usr_regs(struct rt_sigframe __user *sf, struct pt_regs *regs,

	       sigset_t *set)
@@ -94,6 +129,10 @@ 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())

		err |= save_arcv2_regs(&(sf->uc.uc_mcontext), regs);



	err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(sigset_t));



	return err ? -EFAULT : 0;
@@ -109,6 +148,10 @@ 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())

		err |= restore_arcv2_regs(&(sf->uc.uc_mcontext), regs);



	if (err)

		return -EFAULT;