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: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

diff --git a/arch/x86/include/asm/mpx.h b/arch/x86/include/asm/mpx.h
index 61eb4b63c5ec0730a848068e0b129521b04ecb13..d0b1434fb0b691b1e64d43cb2a13304e9258c30f 100644 (file)
--- a/arch/x86/include/asm/mpx.h
+++ b/arch/x86/include/asm/mpx.h
@@ -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)
 {

diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index e6db475164edec4f33e6f056cde5cbdfbe51a556..2155d2c7f49b668f199f5a62846be6c86acd7363 100644 (file)
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -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:

diff --git a/arch/x86/mm/mpx.c b/arch/x86/mm/mpx.c
index e500949bae24534ce7fea11d73bddb2810affa99..2385538e80656aca15b9507827d45885b453cf8d 100644 (file)
--- a/arch/x86/mm/mpx.c
+++ b/arch/x86/mm/mpx.c
@@ -118,14 +118,11 @@ bad_opcode:
  * 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)