kernel.git/arch/x86/kernel/alternative.c, branch linux-3.18.y

kprobes, x86: Allow kprobes on text_poke/hw_breakpoint

2014-04-24T08:03:02Z

Allow kprobes on text_poke/hw_breakpoint because those are not related to the critical int3-debug recursive path of kprobes at this moment. Signed-off-by: Masami Hiramatsu Reviewed-by: Steven Rostedt Cc: Andrew Morton Cc: Borislav Petkov Cc: Fengguang Wu Cc: Jiri Kosina Cc: Oleg Nesterov Cc: Paul Gortmaker Link: http://lkml.kernel.org/r/20140417081807.26341.73219.stgit@ltc230.yrl.intra.hitachi.co.jp Signed-off-by: Ingo Molnar

lockdep, x86/alternatives: Drop ancient lockdep fixup message

2013-09-28T08:09:41Z

It messes up the output of the nodes/cores bootup table and it is obsolete anyway, see 17abecfe651c x86: fix up alternatives with lockdep enabled Signed-off-by: Borislav Petkov Cc: huawei.libin@huawei.com Cc: wangyijing@huawei.com Cc: fenghua.yu@intel.com Cc: guohanjun@huawei.com Cc: paul.gortmaker@windriver.com Link: http://lkml.kernel.org/r/20130927143442.GE4422@pd.tnic Signed-off-by: Ingo Molnar

kprobes/x86: Call out into INT3 handler directly instead of using notifier

2013-07-23T08:12:57Z

In fd4363fff3d96 ("x86: Introduce int3 (breakpoint)-based instruction patching"), the mechanism that was introduced for notifying alternatives code from int3 exception handler that and exception occured was die_notifier. This is however problematic, as early code might be using jump labels even before the notifier registration has been performed, which will then lead to an oops due to unhandled exception. One of such occurences has been encountered by Fengguang: int3: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC Modules linked in: CPU: 1 PID: 0 Comm: swapper/1 Not tainted 3.11.0-rc1-01429-g04bf576 #8 task: ffff88000da1b040 ti: ffff88000da1c000 task.ti: ffff88000da1c000 RIP: 0010:[] [] ttwu_do_wakeup+0x28/0x225 RSP: 0000:ffff88000dd03f10 EFLAGS: 00000006 RAX: 0000000000000000 RBX: ffff88000dd12940 RCX: ffffffff81769c40 RDX: 0000000000000002 RSI: 0000000000000000 RDI: 0000000000000001 RBP: ffff88000dd03f28 R08: ffffffff8176a8c0 R09: 0000000000000002 R10: ffffffff810ff484 R11: ffff88000dd129e8 R12: ffff88000dbc90c0 R13: ffff88000dbc90c0 R14: ffff88000da1dfd8 R15: ffff88000da1dfd8 FS: 0000000000000000(0000) GS:ffff88000dd00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 00000000ffffffff CR3: 0000000001c88000 CR4: 00000000000006e0 Stack: ffff88000dd12940 ffff88000dbc90c0 ffff88000da1dfd8 ffff88000dd03f48 ffffffff81109e2b ffff88000dd12940 0000000000000000 ffff88000dd03f68 ffffffff81109e9e 0000000000000000 0000000000012940 ffff88000dd03f98 Call Trace: [] ttwu_do_activate.constprop.56+0x6d/0x79 [] sched_ttwu_pending+0x67/0x84 [] scheduler_ipi+0x15a/0x2b0 [] smp_reschedule_interrupt+0x38/0x41 [] reschedule_interrupt+0x6d/0x80 [] ? __atomic_notifier_call_chain+0x5/0xc1 [] ? native_safe_halt+0xd/0x16 [] default_idle+0x147/0x282 [] arch_cpu_idle+0x3d/0x5d [] cpu_idle_loop+0x46d/0x5db [] cpu_startup_entry+0x84/0x84 [] start_secondary+0x3c8/0x3d5 [...] Fix this by directly calling poke_int3_handler() from the int3 exception handler (analogically to what ftrace has been doing already), instead of relying on notifier, registration of which might not have yet been finalized by the time of the first trap. Reported-and-tested-by: Fengguang Wu Signed-off-by: Jiri Kosina Acked-by: Masami Hiramatsu Cc: H. Peter Anvin Cc: Fengguang Wu Cc: Steven Rostedt Link: http://lkml.kernel.org/r/alpine.LNX.2.00.1307231007490.14024@pobox.suse.cz Signed-off-by: Ingo Molnar

kprobes/x86: Remove unused text_poke_smp() and text_poke_smp_batch() functions

2013-07-19T07:57:04Z

Since introducing the text_poke_bp() for all text_poke_smp*() callers, text_poke_smp*() are now unused. This patch basically reverts: 3d55cc8a058e ("x86: Add text_poke_smp for SMP cross modifying code") 7deb18dcf047 ("x86: Introduce text_poke_smp_batch() for batch-code modifying") and related commits. This patch also fixes a Kconfig dependency issue on STOP_MACHINE in the case of CONFIG_SMP && !CONFIG_MODULE_UNLOAD. Signed-off-by: Masami Hiramatsu Reviewed-by: Jiri Kosina Cc: H. Peter Anvin Cc: Steven Rostedt Cc: Jason Baron Cc: yrl.pp-manager.tt@hitachi.com Cc: Borislav Petkov Link: http://lkml.kernel.org/r/20130718114753.26675.18714.stgit@mhiramat-M0-7522 Signed-off-by: Ingo Molnar

x86: Introduce int3 (breakpoint)-based instruction patching

2013-07-17T00:55:29Z

Introduce a method for run-time instruction patching on a live SMP kernel based on int3 breakpoint, completely avoiding the need for stop_machine(). The way this is achieved: - add a int3 trap to the address that will be patched - sync cores - update all but the first byte of the patched range - sync cores - replace the first byte (int3) by the first byte of replacing opcode - sync cores According to http://lkml.indiana.edu/hypermail/linux/kernel/1001.1/01530.html synchronization after replacing "all but first" instructions should not be necessary (on Intel hardware), as the syncing after the subsequent patching of the first byte provides enough safety. But there's not only Intel HW out there, and we'd rather be on a safe side. If any CPU instruction execution would collide with the patching, it'd be trapped by the int3 breakpoint and redirected to the provided "handler" (which would typically mean just skipping over the patched region, acting as "nop" has been there, in case we are doing nop -> jump and jump -> nop transitions). Ftrace has been using this very technique since 08d636b ("ftrace/x86: Have arch x86_64 use breakpoints instead of stop machine") for ages already, and jump labels are another obvious potential user of this. Based on activities of Masami Hiramatsu a few years ago. Reviewed-by: Steven Rostedt Reviewed-by: Masami Hiramatsu Signed-off-by: Jiri Kosina Link: http://lkml.kernel.org/r/alpine.LNX.2.00.1307121102440.29788@pobox.suse.cz Signed-off-by: H. Peter Anvin

x86, cpu: Expand cpufeature facility to include cpu bugs

2013-04-02T17:12:52Z

We add another 32-bit vector at the end of the ->x86_capability bitvector which collects bugs present in CPUs. After all, a CPU bug is a kind of a capability, albeit a strange one. Signed-off-by: Borislav Petkov Link: http://lkml.kernel.org/r/1363788448-31325-2-git-send-email-bp@alien8.de Signed-off-by: H. Peter Anvin

Merge branch 'x86-cleanups-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2012-10-01T17:47:45Z

Pull x86/cleanups from Ingo Molnar: "Smaller cleanups" * 'x86-cleanups-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: arch/x86: Remove unecessary semicolons x86, boot: Remove obsolete and unused constant RAMDISK

Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2012-10-01T17:46:27Z

Pull x86/asm changes from Ingo Molnar: "The one change that stands out is the alternatives patching change that prevents us from ever patching back instructions from SMP to UP: this simplifies things and speeds up CPU hotplug. Other than that it's smaller fixes, cleanups and improvements." * 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86: Unspaghettize do_trap() x86_64: Work around old GAS bug x86: Use REP BSF unconditionally x86: Prefer TZCNT over BFS x86/64: Adjust types of temporaries used by ffs()/fls()/fls64() x86: Drop unnecessary kernel_eflags variable on 64-bit x86/smp: Don't ever patch back to UP if we unplug cpus

arch/x86: Remove unecessary semicolons

2012-09-19T15:32:48Z

Found by http://coccinelle.lip6.fr/ Signed-off-by: Peter Senna Tschudin Cc: avi@redhat.com Cc: mtosatti@redhat.com Cc: a.p.zijlstra@chello.nl Cc: rusty@rustcorp.com.au Cc: masami.hiramatsu.pt@hitachi.com Cc: suresh.b.siddha@intel.com Cc: joerg.roedel@amd.com Cc: agordeev@redhat.com Cc: yinghai@kernel.org Cc: bhelgaas@google.com Cc: liuj97@gmail.com Link: http://lkml.kernel.org/r/1347986174-30287-7-git-send-email-peter.senna@gmail.com Signed-off-by: Ingo Molnar

x86/smp: Don't ever patch back to UP if we unplug cpus

2012-08-23T08:45:13Z

We still patch SMP instructions to UP variants if we boot with a single CPU, but not at any other time. In particular, not if we unplug CPUs to return to a single cpu. Paul McKenney points out: mean offline overhead is 6251/48=130.2 milliseconds. If I remove the alternatives_smp_switch() from the offline path [...] the mean offline overhead is 550/42=13.1 milliseconds Basically, we're never going to get those 120ms back, and the code is pretty messy. We get rid of: 1) The "smp-alt-once" boot option. It's actually "smp-alt-boot", the documentation is wrong. It's now the default. 2) The skip_smp_alternatives flag used by suspend. 3) arch_disable_nonboot_cpus_begin() and arch_disable_nonboot_cpus_end() which were only used to set this one flag. Signed-off-by: Rusty Russell Cc: Paul McKenney Cc: Suresh Siddha Cc: Linus Torvalds Cc: Andrew Morton Cc: Peter Zijlstra Link: http://lkml.kernel.org/r/87vcgwwive.fsf@rustcorp.com.au Signed-off-by: Ingo Molnar