On 01/26/2014 01:08 AM, Qiaowei Ren wrote:
> This patch adds new fields about bound violation into siginfo
> structure. si_lower and si_upper are respectively lower bound
> and upper bound when bound violation is caused.
>
> These fields will be set in #BR exception handler by decoding
> the user instruction and constructing the faulting pointer.
> A userspace application can get violation address, lower bound
> and upper bound for bound violation from this new siginfo structure.
>
> Signed-off-by: Qiaowei Ren <qiaowei....@intel.com>
> ---
> arch/x86/include/asm/mpx.h | 19 +++
> arch/x86/kernel/mpx.c | 287
> ++++++++++++++++++++++++++++++++++++
> arch/x86/kernel/traps.c | 6 +
> include/uapi/asm-generic/siginfo.h | 9 +-
> kernel/signal.c | 4 +
> 5 files changed, 324 insertions(+), 1 deletions(-)
>
> diff --git a/arch/x86/include/asm/mpx.h b/arch/x86/include/asm/mpx.h
> index 9652e9e..e099573 100644
> --- a/arch/x86/include/asm/mpx.h
> +++ b/arch/x86/include/asm/mpx.h
> @@ -3,6 +3,7 @@
>
> #include <linux/types.h>
> #include <asm/ptrace.h>
> +#include <asm/insn.h>
>
> #ifdef CONFIG_X86_64
>
> @@ -30,6 +31,22 @@
>
> #endif
>
> +struct mpx_insn {
> + struct insn_field rex_prefix; /* REX prefix */
> + struct insn_field modrm;
> + struct insn_field sib;
> + struct insn_field displacement;
> +
> + unsigned char addr_bytes; /* effective address size */
> + unsigned char limit;
> + unsigned char x86_64;
> +
> + const unsigned char *kaddr; /* kernel address of insn to analyze */
> + const unsigned char *next_byte;
> +};
> +
> +#define MAX_MPX_INSN_SIZE 15
> +
> typedef union {
> struct {
> unsigned long ignored:MPX_IGN_BITS;
> @@ -40,5 +57,7 @@ typedef union {
> } mpx_addr;
>
> void do_mpx_bt_fault(struct xsave_struct *xsave_buf);
> +void do_mpx_bounds(struct pt_regs *regs, siginfo_t *info,
> + struct xsave_struct *xsave_buf);
>
> #endif /* _ASM_X86_MPX_H */
> diff --git a/arch/x86/kernel/mpx.c b/arch/x86/kernel/mpx.c
> index 9e91178..983abf7 100644
> --- a/arch/x86/kernel/mpx.c
> +++ b/arch/x86/kernel/mpx.c
> @@ -91,6 +91,269 @@ int mpx_release(struct task_struct *tsk)
> return 0;
> }
>
> +typedef enum {REG_TYPE_RM, REG_TYPE_INDEX, REG_TYPE_BASE} reg_type_t;
> +static unsigned long get_reg(struct mpx_insn *insn, struct pt_regs *regs,
> + reg_type_t type)
> +{
> + int regno = 0;
> + unsigned char modrm = (unsigned char)insn->modrm.value;
> + unsigned char sib = (unsigned char)insn->sib.value;
> +
> + static const int regoff[] = {
> + offsetof(struct pt_regs, ax),
> + offsetof(struct pt_regs, cx),
> + offsetof(struct pt_regs, dx),
> + offsetof(struct pt_regs, bx),
> + offsetof(struct pt_regs, sp),
> + offsetof(struct pt_regs, bp),
> + offsetof(struct pt_regs, si),
> + offsetof(struct pt_regs, di),
> +#ifdef CONFIG_X86_64
> + offsetof(struct pt_regs, r8),
> + offsetof(struct pt_regs, r9),
> + offsetof(struct pt_regs, r10),
> + offsetof(struct pt_regs, r11),
> + offsetof(struct pt_regs, r12),
> + offsetof(struct pt_regs, r13),
> + offsetof(struct pt_regs, r14),
> + offsetof(struct pt_regs, r15),
> +#endif
> + };
> +
> + switch (type) {
> + case REG_TYPE_RM:
> + regno = X86_MODRM_RM(modrm);
> + if (X86_REX_B(insn->rex_prefix.value) == 1)
> + regno += 8;
> + break;
> +
> + case REG_TYPE_INDEX:
> + regno = X86_SIB_INDEX(sib);
> + if (X86_REX_X(insn->rex_prefix.value) == 1)
> + regno += 8;
> + break;
> +
> + case REG_TYPE_BASE:
> + regno = X86_SIB_BASE(sib);
> + if (X86_REX_B(insn->rex_prefix.value) == 1)
> + regno += 8;
> + break;
> +
> + default:
> + break;
> + }
> +
> + return regs_get_register(regs, regoff[regno]);
> +}
This (and the rest of the decoder) is IMO hideous. Is there any reason
that this belongs in the kernel and not in, say, a libmpx?
(Why on earth does Intel not expose this stuff in cr2 or an MSR or
something?)
--Andy
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
