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Commit b05e3703 authored by Martin Schwidefsky's avatar Martin Schwidefsky
Browse files

[S390] user-copy optimization fallout. 



Fix new restore_sigregs function. It copies the user space copy of the
old psw without correcting the psw.mask and the psw.addr high order bit.
While we are at it, simplify save_sigregs a bit.

Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent aa97b102

arch/s390/kernel/signal.c

+7 −10
Original line number Diff line number Diff line
@@ -113,17 +113,15 @@ sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss, 
/* Returns non-zero on fault. */

static int save_sigregs(struct pt_regs *regs, _sigregs __user *sregs)

{

	unsigned long old_mask = regs->psw.mask;

	_sigregs user_sregs;



	save_access_regs(current->thread.acrs);



	/* Copy a 'clean' PSW mask to the user to avoid leaking

	   information about whether PER is currently on.  */

	regs->psw.mask = PSW_MASK_MERGE(PSW_USER_BITS, regs->psw.mask);

	memcpy(&user_sregs.regs.psw, &regs->psw, sizeof(sregs->regs.psw) +

	       sizeof(sregs->regs.gprs));

	regs->psw.mask = old_mask;

	user_sregs.regs.psw.mask = PSW_MASK_MERGE(PSW_USER_BITS, regs->psw.mask);

	user_sregs.regs.psw.addr = regs->psw.addr;

	memcpy(&user_sregs.regs.gprs, &regs->gprs, sizeof(sregs->regs.gprs));

	memcpy(&user_sregs.regs.acrs, current->thread.acrs,

	       sizeof(sregs->regs.acrs));

	/*
@@ -139,7 +137,6 @@ static int save_sigregs(struct pt_regs *regs, _sigregs __user *sregs) 
/* Returns positive number on error */

static int restore_sigregs(struct pt_regs *regs, _sigregs __user *sregs)

{

	unsigned long old_mask = regs->psw.mask;

	int err;

	_sigregs user_sregs;
@@ -147,12 +144,12 @@ static int restore_sigregs(struct pt_regs *regs, _sigregs __user *sregs) 
	current_thread_info()->restart_block.fn = do_no_restart_syscall;



	err = __copy_from_user(&user_sregs, sregs, sizeof(_sigregs));

	regs->psw.mask = PSW_MASK_MERGE(old_mask, regs->psw.mask);

	regs->psw.addr |= PSW_ADDR_AMODE;

	if (err)

		return err;

	memcpy(&regs->psw, &user_sregs.regs.psw, sizeof(sregs->regs.psw) +

	       sizeof(sregs->regs.gprs));

	regs->psw.mask = PSW_MASK_MERGE(regs->psw.mask,

					user_sregs.regs.psw.mask);

	regs->psw.addr = PSW_ADDR_AMODE | user_sregs.regs.psw.addr;

	memcpy(&regs->gprs, &user_sregs.regs.gprs, sizeof(sregs->regs.gprs));

	memcpy(&current->thread.acrs, &user_sregs.regs.acrs,

	       sizeof(sregs->regs.acrs));

	restore_access_regs(current->thread.acrs);