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Date: Mon, 18 Dec 2017 16:34:10 +0800 From: Rui Wang <rui.y.wang@...el.com> To: linux-kernel@...r.kernel.org, x86@...nel.org Cc: dave.hansen@...ux.intel.com, rui.y.wang@...el.com Subject: [PATCH] x86/mpx/selftests: Fix wrong bounds with old _sigfault I fixed this on my machine and forgot to tell anyone until a recent bug report. The patch almost get lost. Archiving it here. For distributions with old userspace header files, the _sigfault structure is different. mpx-mini-test fails with the following error: [root@...ley]# mpx-mini-test_64 tabletest XSAVE is supported by HW & OS XSAVE processor supported state mask: 0x2ff XSAVE OS supported state mask: 0x2ff BNDREGS: size: 64 user: 1 supervisor: 0 aligned: 0 BNDCSR: size: 64 user: 1 supervisor: 0 aligned: 0 starting mpx bounds table test ERROR: siginfo bounds do not match shadow bounds for register 0 Fix it by using the correct offset of _lower/_upper in _sigfault. RHEL needs this patch to work. Fixes: e754aedc26ef ("x86/mpx, selftests: Add MPX self test") Signed-off-by: Rui Wang <rui.y.wang@...el.com> --- tools/testing/selftests/x86/mpx-mini-test.c | 27 +++++++++++++++++++++++++-- 1 files changed, 25 insertions(+), 2 deletions(-) diff --git a/tools/testing/selftests/x86/mpx-mini-test.c b/tools/testing/selftests/x86/mpx-mini-test.c index ec0f6b4..45035c3 100644 --- a/tools/testing/selftests/x86/mpx-mini-test.c +++ b/tools/testing/selftests/x86/mpx-mini-test.c @@ -315,11 +315,34 @@ static uint64_t read_mpx_status_sig(ucontext_t *uctxt) return si->si_upper; } #else + +/* This deals with old version of _sigfault in some distros +old _sigfault: + struct { + void *si_addr; + } _sigfault; + +new _sigfault: + struct { + void __user *_addr; + int _trapno; + short _addr_lsb; + union { + struct { + void __user *_lower; + void __user *_upper; + } _addr_bnd; + __u32 _pkey; + }; + } _sigfault; +*/ static inline void **__si_bounds_hack(siginfo_t *si) { void *sigfault = &si->_sifields._sigfault; void *end_sigfault = sigfault + sizeof(si->_sifields._sigfault); - void **__si_lower = end_sigfault; + int *trapno = (int*)end_sigfault; + /* skip _trapno and _addr_lsb */ + void **__si_lower = (void**)(trapno + 2); return __si_lower; } @@ -331,7 +354,7 @@ static uint64_t read_mpx_status_sig(ucontext_t *uctxt) static inline void *__si_bounds_upper(siginfo_t *si) { - return (*__si_bounds_hack(si)) + sizeof(void *); + return *(__si_bounds_hack(si) + 1); } #endif -- 1.7.5.4
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