Commit-ID: 71271269ef9a997fb4416b2f8ef3558dd846c7cb Gitweb: https://git.kernel.org/tip/71271269ef9a997fb4416b2f8ef3558dd846c7cb Author: Ricardo Neri <[email protected]> AuthorDate: Fri, 27 Oct 2017 16:51:38 -0700 Committer: Ingo Molnar <[email protected]> CommitDate: Thu, 2 Nov 2017 09:55:14 +0100
x86/insn-eval: Extend get_seg_base_addr() to also obtain segment limit In protected mode, it is common to want to obtain the limit of a segment along with its base address. This is useful, for instance, to verify that an effective address lies within a segment before computing a linear address. Up to this point, this library only computes linear addresses in long mode. Subsequent patches will include support for protected mode. Support to verify the segment limit will be needed. Signed-off-by: Ricardo Neri <[email protected]> Cc: Adam Buchbinder <[email protected]> Cc: Adrian Hunter <[email protected]> Cc: Andrew Morton <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Arnaldo Carvalho de Melo <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Brian Gerst <[email protected]> Cc: Chen Yucong <[email protected]> Cc: Chris Metcalf <[email protected]> Cc: Colin Ian King <[email protected]> Cc: Dave Hansen <[email protected]> Cc: Dmitry Vyukov <[email protected]> Cc: Huang Rui <[email protected]> Cc: Jiri Slaby <[email protected]> Cc: Jonathan Corbet <[email protected]> Cc: Kees Cook <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Lorenzo Stoakes <[email protected]> Cc: Masami Hiramatsu <[email protected]> Cc: Michael S. Tsirkin <[email protected]> Cc: Paolo Bonzini <[email protected]> Cc: Paul Gortmaker <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Qiaowei Ren <[email protected]> Cc: Ravi V. Shankar <[email protected]> Cc: Shuah Khan <[email protected]> Cc: Thomas Garnier <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Vlastimil Babka <[email protected]> Cc: [email protected] Link: http://lkml.kernel.org/r/1509148310-30862-2-git-send-email-ricardo.neri-calde...@linux.intel.com Signed-off-by: Ingo Molnar <[email protected]> --- arch/x86/lib/insn-eval.c | 27 +++++++++++++++++++-------- 1 file changed, 19 insertions(+), 8 deletions(-) diff --git a/arch/x86/lib/insn-eval.c b/arch/x86/lib/insn-eval.c index 1c23ec0..91f08aa 100644 --- a/arch/x86/lib/insn-eval.c +++ b/arch/x86/lib/insn-eval.c @@ -729,25 +729,29 @@ int insn_get_modrm_rm_off(struct insn *insn, struct pt_regs *regs) } /** - * get_seg_base_addr() - obtain base address of a segment + * get_seg_base_limit() - obtain base address and limit of a segment * @insn: Instruction. Must be valid. * @regs: Register values as seen when entering kernel mode * @regoff: Operand offset, in pt_regs, used to resolve segment descriptor * @base: Obtained segment base + * @limit: Obtained segment limit * - * Obtain the base address of the segment associated with the operand @regoff - * and, if any or allowed, override prefixes in @insn. This function is + * Obtain the base address and limit of the segment associated with the operand + * @regoff and, if any or allowed, override prefixes in @insn. This function is * different from insn_get_seg_base() as the latter does not resolve the segment - * associated with the instruction operand. + * associated with the instruction operand. If a limit is not needed (e.g., + * when running in long mode), @limit can be NULL. * * Returns: * - * 0 on success. @base will contain the base address of the resolved segment. + * 0 on success. @base and @limit will contain the base address and of the + * resolved segment, respectively. * * -EINVAL on error. */ -static int get_seg_base_addr(struct insn *insn, struct pt_regs *regs, - int regoff, unsigned long *base) +static int get_seg_base_limit(struct insn *insn, struct pt_regs *regs, + int regoff, unsigned long *base, + unsigned long *limit) { int seg_reg_idx; @@ -762,6 +766,13 @@ static int get_seg_base_addr(struct insn *insn, struct pt_regs *regs, if (*base == -1L) return -EINVAL; + if (!limit) + return 0; + + *limit = get_seg_limit(regs, seg_reg_idx); + if (!(*limit)) + return -EINVAL; + return 0; } @@ -843,7 +854,7 @@ void __user *insn_get_addr_ref(struct insn *insn, struct pt_regs *regs) eff_addr += insn->displacement.value; } - ret = get_seg_base_addr(insn, regs, addr_offset, &seg_base); + ret = get_seg_base_limit(insn, regs, addr_offset, &seg_base, NULL); if (ret) goto out;
