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ARCv2: save ABI registers across signal handling

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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: kernel test robot <lkp@intel.com>
Reported-by: Vladimir Isaev <isaev@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
This commit is contained in:
Vineet Gupta 2021-06-08 19:39:25 -07:00
parent d07f6ca923
commit 96f1b00138
2 changed files with 44 additions and 0 deletions
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1
arch/arc/include/uapi/asm/sigcontext.h
View File

@ -18,6 +18,7 @@
*/
struct sigcontext {
struct user_regs_struct regs;
struct user_regs_arcv2 v2abi;
};
#endif /* _ASM_ARC_SIGCONTEXT_H */

43
arch/arc/kernel/signal.c
View File

@ -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;