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authorRicardo Neri <ricardo.neri-calderon@linux.intel.com>2017-10-27 23:25:38 +0300
committerThomas Gleixner <tglx@linutronix.de>2017-11-01 23:50:11 +0300
commite5e45f11110191740ecb365fa8c7a25814ce8ac8 (patch)
tree0c91441d2c0e9167dc575db84c0e7caaf0578dd8 /arch/x86
parented594e4ba5bfe268d63d7cee3c1a827e3dd5056f (diff)
downloadlinux-e5e45f11110191740ecb365fa8c7a25814ce8ac8.tar.xz
x86/insn-eval: Add a utility function to get register offsets
The function get_reg_offset() returns the offset to the register the argument specifies as indicated in an enumeration of type offset. Callers of this function would need the definition of such enumeration. This is not needed. Instead, add helper functions for this purpose. These functions are useful in cases when, for instance, the caller needs to decide whether the operand is a register or a memory location by looking at the rm part of the ModRM byte. As of now, this is the only helper function that is needed. 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/1509135945-13762-12-git-send-email-ricardo.neri-calderon@linux.intel.com
Diffstat (limited to 'arch/x86')
-rw-r--r--arch/x86/include/asm/insn-eval.h1
-rw-r--r--arch/x86/lib/insn-eval.c17
2 files changed, 18 insertions, 0 deletions
diff --git a/arch/x86/include/asm/insn-eval.h b/arch/x86/include/asm/insn-eval.h
index 5cab1b1da84d..7e8c9633a377 100644
--- a/arch/x86/include/asm/insn-eval.h
+++ b/arch/x86/include/asm/insn-eval.h
@@ -12,5 +12,6 @@
#include <asm/ptrace.h>
void __user *insn_get_addr_ref(struct insn *insn, struct pt_regs *regs);
+int insn_get_modrm_rm_off(struct insn *insn, struct pt_regs *regs);
#endif /* _ASM_X86_INSN_EVAL_H */
diff --git a/arch/x86/lib/insn-eval.c b/arch/x86/lib/insn-eval.c
index 4931d9252dde..405ffeb1c382 100644
--- a/arch/x86/lib/insn-eval.c
+++ b/arch/x86/lib/insn-eval.c
@@ -100,6 +100,23 @@ static int get_reg_offset(struct insn *insn, struct pt_regs *regs,
return regoff[regno];
}
+/**
+ * insn_get_modrm_rm_off() - Obtain register in r/m part of the ModRM byte
+ * @insn: Instruction containing the ModRM byte
+ * @regs: Register values as seen when entering kernel mode
+ *
+ * Returns:
+ *
+ * The register indicated by the r/m part of the ModRM byte. The
+ * register is obtained as an offset from the base of pt_regs. In specific
+ * cases, the returned value can be -EDOM to indicate that the particular value
+ * of ModRM does not refer to a register and shall be ignored.
+ */
+int insn_get_modrm_rm_off(struct insn *insn, struct pt_regs *regs)
+{
+ return get_reg_offset(insn, regs, REG_TYPE_RM);
+}
+
/*
* return the address being referenced be instruction
* for rm=3 returning the content of the rm reg