From 5154d4f2adfdabe5aeb247e5b2b6b10fae5f6d50 Mon Sep 17 00:00:00 2001 From: Denys Vlasenko Date: Thu, 12 Feb 2015 20:18:52 +0100 Subject: [PATCH] uprobes/x86: Fix 2-byte opcode table Enabled probing of lar, lsl, popcnt, lddqu, prefetch insns. They should be safe to probe, they throw no exceptions. Enabled probing of 3-byte opcodes 0f 38-3f xx - these are vector isns, so should be safe. Enabled probing of many currently undefined 0f xx insns. At the rate new vector instructions are getting added, we don't want to constantly enable more bits. We want to only occasionally *disable* ones which for some reason can't be probed. This includes 0f 24,26 opcodes, which are undefined since Pentium. On 486, they were "mov to/from test register". Explained more fully what 0f 78,79 opcodes are. Explained what 0f ae opcode is. (It's unclear why we don't allow probing it, but let's not change it for now). Signed-off-by: Denys Vlasenko Cc: Andy Lutomirski Cc: Jim Keniston Cc: Masami Hiramatsu Cc: Oleg Nesterov Cc: Srikar Dronamraju Link: http://lkml.kernel.org/r/1423768732-32194-3-git-send-email-dvlasenk@redhat.com Signed-off-by: Ingo Molnar --- arch/x86/kernel/uprobes.c | 52 +++++++++++++-------------------------- 1 file changed, 17 insertions(+), 35 deletions(-) diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c index aa1da96d09ff..81f8adb0679e 100644 --- a/arch/x86/kernel/uprobes.c +++ b/arch/x86/kernel/uprobes.c @@ -189,61 +189,43 @@ static volatile u32 good_insns_64[256 / 32] = { * 0f 01 - SGDT/SIDT/LGDT/LIDT/SMSW/-/LMSW/INVLPG group. * Also encodes tons of other system insns if mod=11. * Some are in fact non-system: xend, xtest, rdtscp, maybe more - * 0f 02 - lar (why? should be safe, it throws no exceptipons) - * 0f 03 - lsl (why? should be safe, it throws no exceptipons) - * 0f 04 - undefined * 0f 05 - syscall * 0f 06 - clts (CPL0 insn) * 0f 07 - sysret * 0f 08 - invd (CPL0 insn) * 0f 09 - wbinvd (CPL0 insn) - * 0f 0a - undefined * 0f 0b - ud2 - * 0f 0c - undefined - * 0f 0d - prefetchFOO (amd prefetch insns) - * 0f 18 - prefetchBAR (intel prefetch insns) - * 0f 24 - mov from test regs (perhaps entire 20-27 area can be disabled (special reg ops)) - * 0f 25 - undefined - * 0f 26 - mov to test regs - * 0f 27 - undefined - * 0f 30 - wrmsr (CPL0 insn) + * 0f 30 - wrmsr (CPL0 insn) (then why rdmsr is allowed, it's also CPL0 insn?) * 0f 34 - sysenter * 0f 35 - sysexit - * 0f 36 - undefined * 0f 37 - getsec - * 0f 38-3f - 3-byte opcodes (why?? all look safe) - * 0f 78 - vmread - * 0f 79 - vmwrite - * 0f 7a - undefined - * 0f 7b - undefined - * 0f 7c - undefined - * 0f 7d - undefined - * 0f a6 - undefined - * 0f a7 - undefined - * 0f b8 - popcnt (why?? it's an ordinary ALU op) - * 0f d0 - undefined - * 0f f0 - lddqu (why?? it's an ordinary vector load op) - * 0f ff - undefined + * 0f 78 - vmread (Intel VMX. CPL0 insn) + * 0f 79 - vmwrite (Intel VMX. CPL0 insn) + * Note: with prefixes, these two opcodes are + * extrq/insertq/AVX512 convert vector ops. + * 0f ae - group15: [f]xsave,[f]xrstor,[v]{ld,st}mxcsr,clflush[opt], + * {rd,wr}{fs,gs}base,{s,l,m}fence. + * Why? They are all user-executable. */ static volatile u32 good_2byte_insns[256 / 32] = { /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ /* ---------------------------------------------- */ - W(0x00, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1) | /* 00 */ - W(0x10, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1) , /* 10 */ - W(0x20, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1) | /* 20 */ - W(0x30, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) , /* 30 */ + W(0x00, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 1, 0, 1, 1, 1, 1) | /* 00 */ + W(0x10, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 10 */ + W(0x20, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 20 */ + W(0x30, 0, 1, 1, 1, 0, 0, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1) , /* 30 */ W(0x40, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 40 */ W(0x50, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 50 */ W(0x60, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 60 */ - W(0x70, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1) , /* 70 */ + W(0x70, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1) , /* 70 */ W(0x80, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 80 */ W(0x90, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 90 */ - W(0xa0, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 1) | /* a0 */ - W(0xb0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1) , /* b0 */ + W(0xa0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1) | /* a0 */ + W(0xb0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* b0 */ W(0xc0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* c0 */ - W(0xd0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* d0 */ + W(0xd0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* d0 */ W(0xe0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* e0 */ - W(0xf0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0) /* f0 */ + W(0xf0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) /* f0 */ /* ---------------------------------------------- */ /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ }; -- 2.34.1