linux-dev - Linux kernel development work

Age	Commit message (Collapse)	Author	Files	Lines
2014-11-18	x86: Remove arbitrary instruction size limit in instruction decoder	Dave Hansen	1	-1/+1
	The current x86 instruction decoder steps along through the instruction stream but always ensures that it never steps farther than the largest possible instruction size (MAX_INSN_SIZE). The MPX code is now going to be doing some decoding of userspace instructions. We copy those from userspace in to the kernel and they're obviously completely untrusted coming from userspace. In addition to the constraint that instructions can only be so long, we also have to be aware of how long the buffer is that came in from userspace. This _looks_ to be similar to what the perf and kprobes is doing, but it's unclear to me whether they are affected. The whole reason we need this is that it is perfectly valid to be executing an instruction within MAX_INSN_SIZE bytes of an unreadable page. We should be able to gracefully handle short reads in those cases. This adds support to the decoder to record how long the buffer being decoded is and to refuse to "validate" the instruction if we would have gone over the end of the buffer to decode it. The kprobes code probably needs to be looked at here a bit more carefully. This patch still respects the MAX_INSN_SIZE limit there but the kprobes code does look like it might be able to be a bit more strict than it currently is. Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Acked-by: Jim Keniston <jkenisto@us.ibm.com> Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: x86@kernel.org Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Paul Mackerras <paulus@samba.org> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Cc: "David S. Miller" <davem@davemloft.net> Link: http://lkml.kernel.org/r/20141114153957.E6B01535@viggo.jf.intel.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2013-01-24	arch/x86/tools/insn_sanity.c: Identify source of messages	Andrew Morton	1	-2/+8
	The kernel build prints: Building modules, stage 2. TEST posttest MODPOST 3821 modules TEST posttest Success: decoded and checked 1000000 random instructions with 0 errors (seed:0xaac4bc47) CC arch/x86/boot/a20.o CC arch/x86/boot/cmdline.o AS arch/x86/boot/copy.o HOSTCC arch/x86/boot/mkcpustr CC arch/x86/boot/cpucheck.o CC arch/x86/boot/early_serial_console.o which is irritating because you don't know what program is proudly pronouncing its success. So, as described in "console mode programming user interface guidelines version 101" which doesn't exist, change this program to identify the source of its messages. Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2011-12-05	x86/tools: Add decoded instruction dump mode	Masami Hiramatsu	1	-3/+4
	Add instruction dump mode to insn_sanity tool for checking decoder really decoded instructions. This mode is enabled when passing double -v (-vv) to insn_sanity. It is useful for who wants to check whether the decoder can decode some instructions correctly. e.g. $ echo 0f 73 10 11 \| ./insn_sanity -y -vv -i - Instruction = { .prefixes = { .value = 0, bytes[] = {0, 0, 0, 0}, .got = 1, .nbytes = 0}, .rex_prefix = { .value = 0, bytes[] = {0, 0, 0, 0}, .got = 1, .nbytes = 0}, .vex_prefix = { .value = 0, bytes[] = {0, 0, 0, 0}, .got = 1, .nbytes = 0}, .opcode = { .value = 29455, bytes[] = {f, 73, 0, 0}, .got = 1, .nbytes = 2}, .modrm = { .value = 16, bytes[] = {10, 0, 0, 0}, .got = 1, .nbytes = 1}, .sib = { .value = 0, bytes[] = {0, 0, 0, 0}, .got = 1, .nbytes = 0}, .displacement = { .value = 0, bytes[] = {0, 0, 0, 0}, .got = 1, .nbytes = 0}, .immediate1 = { .value = 17, bytes[] = {11, 0, 0, 0}, .got = 1, .nbytes = 1}, .immediate2 = { .value = 0, bytes[] = {0, 0, 0, 0}, .got = 0, .nbytes = 0}, .attr = 44800, .opnd_bytes = 4, .addr_bytes = 8, .length = 4, .x86_64 = 1, .kaddr = 0x7fff0f7d9430} Success: decoded and checked 1 given instructions with 0 errors (seed:0x0) Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: yrl.pp-manager.tt@hitachi.com Link: http://lkml.kernel.org/r/20111205120603.15475.91192.stgit@cloud Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-12-05	x86/tools: Fix insn_sanity message outputs	Masami Hiramatsu	1	-2/+2
	Fix x86 instruction decoder test to dump all error messages to stderr and others to stdout. Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: yrl.pp-manager.tt@hitachi.com Link: http://lkml.kernel.org/r/20111205120550.15475.70149.stgit@cloud Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-12-05	x86/tools: Fix instruction decoder message output	Masami Hiramatsu	1	-4/+3
	Fix instruction decoder test (insn_sanity), so that it doesn't show both info and error messages twice on same instruction. (In that case, show only error message) Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: yrl.pp-manager.tt@hitachi.com Link: http://lkml.kernel.org/r/20111205120545.15475.7928.stgit@cloud Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-11-10	x86, perf: Add a build-time sanity test to the x86 decoder	Masami Hiramatsu	1	-0/+275
	Add a sanity test of x86 insn decoder against a stream of randomly generated input, at build time. This test is also able to reproduce any bug that might trigger by allowing the passing of random-seed and iteration-number to the test, or by passing input which has invalid byte code. Changes in V2: - Code cleanup. - Show how to reproduce the error by insn_sanity test. Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: acme@redhat.com Cc: ming.m.lin@intel.com Cc: robert.richter@amd.com Cc: ravitillo@lbl.gov Cc: yrl.pp-manager.tt@hitachi.com Cc: Andi Kleen <andi@firstfloor.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/20111020140109.20938.92572.stgit@localhost.localdomain Signed-off-by: Ingo Molnar <mingo@elte.hu>