Commit-ID: e5e45f11110191740ecb365fa8c7a25814ce8ac8 Gitweb: https://git.kernel.org/tip/e5e45f11110191740ecb365fa8c7a25814ce8ac8 Author: Ricardo Neri <[email protected]> AuthorDate: Fri, 27 Oct 2017 13:25:38 -0700 Committer: Thomas Gleixner <[email protected]> CommitDate: Wed, 1 Nov 2017 21:50:11 +0100
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 <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> Reviewed-by: Borislav Petkov <[email protected]> Cc: "Michael S. Tsirkin" <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Dave Hansen <[email protected]> Cc: [email protected] Cc: Adrian Hunter <[email protected]> Cc: Paul Gortmaker <[email protected]> Cc: Huang Rui <[email protected]> Cc: Qiaowei Ren <[email protected]> Cc: Shuah Khan <[email protected]> Cc: Kees Cook <[email protected]> Cc: Jonathan Corbet <[email protected]> Cc: Jiri Slaby <[email protected]> Cc: Dmitry Vyukov <[email protected]> Cc: "Ravi V. Shankar" <[email protected]> Cc: Chris Metcalf <[email protected]> Cc: Brian Gerst <[email protected]> Cc: Arnaldo Carvalho de Melo <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Colin Ian King <[email protected]> Cc: Chen Yucong <[email protected]> Cc: Adam Buchbinder <[email protected]> Cc: Vlastimil Babka <[email protected]> Cc: Lorenzo Stoakes <[email protected]> Cc: Masami Hiramatsu <[email protected]> Cc: Paolo Bonzini <[email protected]> Cc: Andrew Morton <[email protected]> Cc: Thomas Garnier <[email protected]> Link: https://lkml.kernel.org/r/1509135945-13762-12-git-send-email-ricardo.neri-calde...@linux.intel.com --- arch/x86/include/asm/insn-eval.h | 1 + arch/x86/lib/insn-eval.c | 17 +++++++++++++++++ 2 files changed, 18 insertions(+) diff --git a/arch/x86/include/asm/insn-eval.h b/arch/x86/include/asm/insn-eval.h index 5cab1b1..7e8c963 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 4931d92..405ffeb 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
