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authorRicardo Neri <ricardo.neri-calderon@linux.intel.com>2017-10-27 23:25:39 +0300
committerThomas Gleixner <tglx@linutronix.de>2017-11-01 23:50:11 +0300
commit536b815388f7f4d2a7cd1418939902fb037ea370 (patch)
tree97891581ae044a8987bd309bc4baff6739976c68 /arch/x86/lib
parente5e45f11110191740ecb365fa8c7a25814ce8ac8 (diff)
downloadlinux-536b815388f7f4d2a7cd1418939902fb037ea370.tar.xz
x86/insn-eval: Add utility function to identify string instructions
String instructions are special because, in protected mode, the linear address is always obtained via the ES segment register in operands that use the (E)DI register; the DS segment register in operands that use the (E)SI register. Furthermore, segment override prefixes are ignored when calculating a linear address involving the (E)DI register; segment override prefixes can be used when calculating linear addresses involving the (E)SI register. It follows that linear addresses are calculated differently for the case of string instructions. The purpose of this utility function is to identify such instructions for callers to determine a linear address correctly. Note that this function only identifies string instructions; it does not determine what segment register to use in the address computation. That is left to callers. A subsequent commmit introduces a function to determine the segment register to use given the instruction, operands and segment override prefixes. Signed-off-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Borislav Petkov <bp@suse.de> Cc: "Michael S. Tsirkin" <mst@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: ricardo.neri@intel.com Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Huang Rui <ray.huang@amd.com> Cc: Qiaowei Ren <qiaowei.ren@intel.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Kees Cook <keescook@chromium.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: "Ravi V. Shankar" <ravi.v.shankar@intel.com> Cc: Chris Metcalf <cmetcalf@mellanox.com> Cc: Brian Gerst <brgerst@gmail.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Colin Ian King <colin.king@canonical.com> Cc: Chen Yucong <slaoub@gmail.com> Cc: Adam Buchbinder <adam.buchbinder@gmail.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Lorenzo Stoakes <lstoakes@gmail.com> Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Thomas Garnier <thgarnie@google.com> Link: https://lkml.kernel.org/r/1509135945-13762-13-git-send-email-ricardo.neri-calderon@linux.intel.com
Diffstat (limited to 'arch/x86/lib')
-rw-r--r--arch/x86/lib/insn-eval.c28
1 files changed, 28 insertions, 0 deletions
diff --git a/arch/x86/lib/insn-eval.c b/arch/x86/lib/insn-eval.c
index 405ffeb1c382..ac7b87c228b9 100644
--- a/arch/x86/lib/insn-eval.c
+++ b/arch/x86/lib/insn-eval.c
@@ -19,6 +19,34 @@ enum reg_type {
REG_TYPE_BASE,
};
+/**
+ * is_string_insn() - Determine if instruction is a string instruction
+ * @insn: Instruction containing the opcode to inspect
+ *
+ * Returns:
+ *
+ * true if the instruction, determined by the opcode, is any of the
+ * string instructions as defined in the Intel Software Development manual.
+ * False otherwise.
+ */
+static bool is_string_insn(struct insn *insn)
+{
+ insn_get_opcode(insn);
+
+ /* All string instructions have a 1-byte opcode. */
+ if (insn->opcode.nbytes != 1)
+ return false;
+
+ switch (insn->opcode.bytes[0]) {
+ case 0x6c ... 0x6f: /* INS, OUTS */
+ case 0xa4 ... 0xa7: /* MOVS, CMPS */
+ case 0xaa ... 0xaf: /* STOS, LODS, SCAS */
+ return true;
+ default:
+ return false;
+ }
+}
+
static int get_reg_offset(struct insn *insn, struct pt_regs *regs,
enum reg_type type)
{