Commit 8d68fa0e authored by Eric W. Biederman's avatar Eric W. Biederman
Browse files

signal/x86: Move mpx siginfo generation into do_bounds 



This separates the logic of generating the signal from the logic of
gathering the information about the bounds violation.

Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatar"Eric W. Biederman" <ebiederm@xmission.com>
parent 8a35eb22

arch/x86/include/asm/mpx.h

+9 −3
Original line number Diff line number Diff line
@@ -57,8 +57,14 @@ 
#define MPX_BNDCFG_ADDR_MASK	(~((1UL<<MPX_BNDCFG_TAIL)-1))

#define MPX_BNDSTA_ERROR_CODE	0x3



struct mpx_fault_info {

	void __user *addr;

	void __user *lower;

	void __user *upper;

};



#ifdef CONFIG_X86_INTEL_MPX

siginfo_t *mpx_generate_siginfo(struct pt_regs *regs);

int mpx_fault_info(struct mpx_fault_info *info, struct pt_regs *regs);

int mpx_handle_bd_fault(void);

static inline int kernel_managing_mpx_tables(struct mm_struct *mm)

{
@@ -78,9 +84,9 @@ void mpx_notify_unmap(struct mm_struct *mm, struct vm_area_struct *vma, 
unsigned long mpx_unmapped_area_check(unsigned long addr, unsigned long len,

		unsigned long flags);

#else

static inline siginfo_t *mpx_generate_siginfo(struct pt_regs *regs)

static inline int mpx_fault_info(struct mpx_fault_info *info, struct pt_regs *regs)

{

	return NULL;

	return -EINVAL;

}

static inline int mpx_handle_bd_fault(void)

{

arch/x86/kernel/traps.c

+14 −5
Original line number Diff line number Diff line
@@ -455,7 +455,6 @@ dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code) 
dotraplinkage void do_bounds(struct pt_regs *regs, long error_code)

{

	const struct mpx_bndcsr *bndcsr;

	siginfo_t *info;



	RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");

	if (notify_die(DIE_TRAP, "bounds", regs, error_code,
@@ -493,8 +492,11 @@ dotraplinkage void do_bounds(struct pt_regs *regs, long error_code) 
			goto exit_trap;

		break; /* Success, it was handled */

	case 1: /* Bound violation. */

		info = mpx_generate_siginfo(regs);

		if (IS_ERR(info)) {

	{

		struct mpx_fault_info mpx;

		struct siginfo info;



		if (mpx_fault_info(&mpx, regs)) {

			/*

			 * We failed to decode the MPX instruction.  Act as if

			 * the exception was not caused by MPX.
@@ -508,9 +510,16 @@ dotraplinkage void do_bounds(struct pt_regs *regs, long error_code) 
		 * allows and application to possibly handle the

		 * #BR exception itself.

		 */

		do_trap(X86_TRAP_BR, SIGSEGV, "bounds", regs, error_code, info);

		kfree(info);

		clear_siginfo(&info);

		info.si_signo = SIGSEGV;

		info.si_errno = 0;

		info.si_code  = SEGV_BNDERR;

		info.si_addr  = mpx.addr;

		info.si_lower = mpx.lower;

		info.si_upper = mpx.upper;

		do_trap(X86_TRAP_BR, SIGSEGV, "bounds", regs, error_code, &info);

		break;

	}

	case 0: /* No exception caused by Intel MPX operations. */

		goto exit_trap;

	default:

arch/x86/mm/mpx.c

+9 −21
Original line number Diff line number Diff line
@@ -118,14 +118,11 @@ static int mpx_insn_decode(struct insn *insn, 
 * anything it wants in to the instructions.  We can not

 * trust anything about it.  They might not be valid

 * instructions or might encode invalid registers, etc...

 *

 * The caller is expected to kfree() the returned siginfo_t.

 */

siginfo_t *mpx_generate_siginfo(struct pt_regs *regs)

int mpx_fault_info(struct mpx_fault_info *info, struct pt_regs *regs)

{

	const struct mpx_bndreg_state *bndregs;

	const struct mpx_bndreg *bndreg;

	siginfo_t *info = NULL;

	struct insn insn;

	uint8_t bndregno;

	int err;
@@ -153,11 +150,6 @@ siginfo_t *mpx_generate_siginfo(struct pt_regs *regs) 
	/* now go select the individual register in the set of 4 */

	bndreg = &bndregs->bndreg[bndregno];



	info = kzalloc(sizeof(*info), GFP_KERNEL);

	if (!info) {

		err = -ENOMEM;

		goto err_out;

	}

	/*

	 * The registers are always 64-bit, but the upper 32

	 * bits are ignored in 32-bit mode.  Also, note that the
@@ -168,27 +160,23 @@ siginfo_t *mpx_generate_siginfo(struct pt_regs *regs) 
	 * complains when casting from integers to different-size

	 * pointers.

	 */

	info->si_lower = (void __user *)(unsigned long)bndreg->lower_bound;

	info->si_upper = (void __user *)(unsigned long)~bndreg->upper_bound;

	info->si_addr_lsb = 0;

	info->si_signo = SIGSEGV;

	info->si_errno = 0;

	info->si_code = SEGV_BNDERR;

	info->si_addr = insn_get_addr_ref(&insn, regs);

	info->lower = (void __user *)(unsigned long)bndreg->lower_bound;

	info->upper = (void __user *)(unsigned long)~bndreg->upper_bound;

	info->addr  = insn_get_addr_ref(&insn, regs);



	/*

	 * We were not able to extract an address from the instruction,

	 * probably because there was something invalid in it.

	 */

	if (info->si_addr == (void __user *)-1) {

	if (info->addr == (void __user *)-1) {

		err = -EINVAL;

		goto err_out;

	}

	trace_mpx_bounds_register_exception(info->si_addr, bndreg);

	return info;

	trace_mpx_bounds_register_exception(info->addr, bndreg);

	return 0;

err_out:

	/* info might be NULL, but kfree() handles that */

	kfree(info);

	return ERR_PTR(err);

	return err;

}



static __user void *mpx_get_bounds_dir(void)