kernel/arch/powerpc/lib/code-patching.c, branch linux-4.16.y

powerpc/lib/feature-fixups: use raw_patch_instruction()

2018-01-21T04:06:25Z

feature fixups need to use patch_instruction() early in the boot, even before the code is relocated to its final address, requiring patch_instruction() to use PTRRELOC() in order to address data. But feature fixups applies on code before it is set to read only, even for modules. Therefore, feature fixups can use raw_patch_instruction() instead. Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman

powerpc/lib/code-patching: refactor patch_instruction()

2018-01-21T04:06:25Z

patch_instruction() uses almost the same sequence as __patch_instruction() This patch refactor it so that patch_instruction() uses __patch_instruction() instead of duplicating code. Signed-off-by: Christophe Leroy Acked-by: Balbir Singh Signed-off-by: Michael Ellerman

powerpc/modules: Don't try to restore r2 after a sibling call

2017-12-11T02:03:29Z

When attempting to load a livepatch module, I got the following error: module_64: patch_module: Expect noop after relocate, got 3c820000 The error was triggered by the following code in unregister_netdevice_queue(): 14c: 00 00 00 48 b 14c 14c: R_PPC64_REL24 net_set_todo 150: 00 00 82 3c addis r4,r2,0 GCC didn't insert a nop after the branch to net_set_todo() because it's a sibling call, so it never returns. The nop isn't needed after the branch in that case. Signed-off-by: Josh Poimboeuf Acked-by: Naveen N. Rao Reviewed-and-tested-by: Kamalesh Babulal Signed-off-by: Michael Ellerman

powerpc: Fix boot on BOOK3S_32 with CONFIG_STRICT_KERNEL_RWX

2017-11-22T12:04:20Z

On powerpc32, patch_instruction() is called by apply_feature_fixups() which is called from early_init() There is the following note in front of early_init(): * Note that the kernel may be running at an address which is different * from the address that it was linked at, so we must use RELOC/PTRRELOC * to access static data (including strings). -- paulus Therefore, slab_is_available() cannot be called yet, and text_poke_area must be addressed with PTRRELOC() Fixes: 95902e6c8864 ("powerpc/mm: Implement STRICT_KERNEL_RWX on PPC32") Cc: stable@vger.kernel.org # v4.14+ Reported-by: Meelis Roos Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman

powerpc/lib/code-patching: Use alternate map for patch_instruction()

2017-07-03T13:12:19Z

This patch creates the window using text_poke_area, allocated via get_vm_area(). text_poke_area is per CPU to avoid locking. text_poke_area for each cpu is setup using late_initcall, prior to setup of these alternate mapping areas, we continue to use direct write to change/modify kernel text. With the ability to use alternate mappings to write to kernel text, it provides us the freedom to then turn text read-only and implement CONFIG_STRICT_KERNEL_RWX. This code is CPU hotplug aware to ensure that the we have mappings for any new cpus as they come online and tear down mappings for any CPUs that go offline. Signed-off-by: Balbir Singh Signed-off-by: Michael Ellerman

powerpc/kprobes: Convert __kprobes to NOKPROBE_SYMBOL()

2017-04-23T10:32:25Z

Along similar lines as commit 9326638cbee2 ("kprobes, x86: Use NOKPROBE_SYMBOL() instead of __kprobes annotation"), convert __kprobes annotation to either NOKPROBE_SYMBOL() or nokprobe_inline. The latter forces inlining, in which case the caller needs to be added to NOKPROBE_SYMBOL(). Also: - blacklist arch_deref_entry_point(), and - convert a few regular inlines to nokprobe_inline in lib/sstep.c A key benefit is the ability to detect such symbols as being blacklisted. Before this patch: $ cat /sys/kernel/debug/kprobes/blacklist | grep read_mem $ perf probe read_mem Failed to write event: Invalid argument Error: Failed to add events. $ dmesg | tail -1 [ 3736.112815] Could not insert probe at _text+10014968: -22 After patch: $ cat /sys/kernel/debug/kprobes/blacklist | grep read_mem 0xc000000000072b50-0xc000000000072d20 read_mem $ perf probe read_mem read_mem is blacklisted function, skip it. Added new events: (null):(null) (on read_mem) probe:read_mem (on read_mem) You can now use it in all perf tools, such as: perf record -e probe:read_mem -aR sleep 1 $ grep " read_mem" /proc/kallsyms c000000000072b50 t read_mem c0000000005f3b40 t read_mem $ cat /sys/kernel/debug/kprobes/list c0000000005f3b48 k read_mem+0x8 [DISABLED] Acked-by: Masami Hiramatsu Signed-off-by: Naveen N. Rao [mpe: Minor change log formatting, fix up some conflicts] Signed-off-by: Michael Ellerman

kprobes: move kprobe declarations to asm-generic/kprobes.h

2017-02-28T02:43:45Z

Often all is needed is these small helpers, instead of compiler.h or a full kprobes.h. This is important for asm helpers, in fact even some asm/kprobes.h make use of these helpers... instead just keep a generic asm file with helpers useful for asm code with the least amount of clutter as possible. Likewise we need now to also address what to do about this file for both when architectures have CONFIG_HAVE_KPROBES, and when they do not. Then for when architectures have CONFIG_HAVE_KPROBES but have disabled CONFIG_KPROBES. Right now most asm/kprobes.h do not have guards against CONFIG_KPROBES, this means most architecture code cannot include asm/kprobes.h safely. Correct this and add guards for architectures missing them. Additionally provide architectures that not have kprobes support with the default asm-generic solution. This lets us force asm/kprobes.h on the header include/linux/kprobes.h always, but most importantly we can now safely include just asm/kprobes.h on architecture code without bringing the full kitchen sink of header files. Two architectures already provided a guard against CONFIG_KPROBES on its kprobes.h: sh, arch. The rest of the architectures needed gaurds added. We avoid including any not-needed headers on asm/kprobes.h unless kprobes have been enabled. In a subsequent atomic change we can try now to remove compiler.h from include/linux/kprobes.h. During this sweep I've also identified a few architectures defining a common macro needed for both kprobes and ftrace, that of the definition of the breakput instruction up. Some refer to this as BREAKPOINT_INSTRUCTION. This must be kept outside of the #ifdef CONFIG_KPROBES guard. [mcgrof@kernel.org: fix arm64 build] Link: http://lkml.kernel.org/r/CAB=NE6X1WMByuARS4mZ1g9+W=LuVBnMDnh_5zyN0CLADaVh=Jw@mail.gmail.com [sfr@canb.auug.org.au: fixup for kprobes declarations moving] Link: http://lkml.kernel.org/r/20170214165933.13ebd4f4@canb.auug.org.au Link: http://lkml.kernel.org/r/20170203233139.32682-1-mcgrof@kernel.org Signed-off-by: Luis R. Rodriguez Signed-off-by: Stephen Rothwell Acked-by: Masami Hiramatsu Cc: Arnd Bergmann Cc: Masami Hiramatsu Cc: Ananth N Mavinakayanahalli Cc: Anil S Keshavamurthy Cc: David S. Miller Cc: Ingo Molnar Cc: Thomas Gleixner Cc: H. Peter Anvin Cc: Andy Lutomirski Cc: Steven Rostedt Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

powerpc/kprobes: Implement Optprobes

2017-02-10T02:28:04Z

Current infrastructure of kprobe uses the unconditional trap instruction to probe a running kernel. Optprobe allows kprobe to replace the trap with a branch instruction to a detour buffer. Detour buffer contains instructions to create an in memory pt_regs. Detour buffer also has a call to optimized_callback() which in turn call the pre_handler(). After the execution of the pre-handler, a call is made for instruction emulation. The NIP is determined in advanced through dummy instruction emulation and a branch instruction is created to the NIP at the end of the trampoline. To address the limitation of branch instruction in POWER architecture, detour buffer slot is allocated from a reserved area. For the time being, 64KB is reserved in memory for this purpose. Instructions which can be emulated using analyse_instr() are the candidates for optimization. Before optimization ensure that the address range between the detour buffer allocated and the instruction being probed is within +/- 32MB. Signed-off-by: Anju T Sudhakar Signed-off-by: Naveen N. Rao Acked-by: Masami Hiramatsu Signed-off-by: Michael Ellerman

powerpc: Add helper to check if offset is within relative branch range

2017-02-10T02:28:03Z

To permit the use of relative branch instruction in powerpc, the target address has to be relatively nearby, since the address is specified in an immediate field (24 bit filed) in the instruction opcode itself. Here nearby refers to 32MB on either side of the current instruction. This patch verifies whether the target address is within +/- 32MB range or not. Signed-off-by: Naveen N. Rao Signed-off-by: Anju T Sudhakar Signed-off-by: Michael Ellerman

Replace with globally

2016-12-24T19:46:01Z

This was entirely automated, using the script by Al: PATT='^[[:blank:]]*#[[:blank:]]*include[[:blank:]]*' sed -i -e "s!$PATT!#include !" \ $(git grep -l "$PATT"|grep -v ^include/linux/uaccess.h) to do the replacement at the end of the merge window. Requested-by: Al Viro Signed-off-by: Linus Torvalds