kernel/tools/objtool/arch/x86/decode.c, branch linux-5.1.y

objtool: Fix Clang enum conversion warning

2017-12-28T12:11:13Z

Fix the following Clang enum conversion warning: arch/x86/decode.c:141:20: error: implicit conversion from enumeration type 'enum op_src_type' to different enumeration type 'enum op_dest_type' [-Werror,-Wenum-conversion] op->dest.type = OP_SRC_REG; ~ ^~~~~~~~~~ It just happened to work before because OP_SRC_REG and OP_DEST_REG have the same value. Signed-off-by: Lukas Bulwahn Signed-off-by: Josh Poimboeuf Reviewed-by: Nicholas Mc Guire Reviewed-by: Nick Desaulniers Cc: Jiri Slaby Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Fixes: baa41469a7b9 ("objtool: Implement stack validation 2.0") Link: http://lkml.kernel.org/r/b4156c5738bae781c392e7a3691aed4514ebbdf2.1514323568.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar

objtool: Move synced files to their original relative locations

2017-11-07T09:48:23Z

This will enable more straightforward comparisons, and it also makes the files 100% identical. Suggested-by: Ingo Molnar Signed-off-by: Josh Poimboeuf Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/407b2aaa317741f48fcf821592c0e96ab3be1890.1509974346.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar

objtool: Support unoptimized frame pointer setup

2017-09-28T05:25:54Z

Arnd Bergmann reported a bunch of warnings like: crypto/jitterentropy.o: warning: objtool: jent_fold_time()+0x3b: call without frame pointer save/setup crypto/jitterentropy.o: warning: objtool: jent_stuck()+0x1d: call without frame pointer save/setup crypto/jitterentropy.o: warning: objtool: jent_unbiased_bit()+0x15: call without frame pointer save/setup crypto/jitterentropy.o: warning: objtool: jent_read_entropy()+0x32: call without frame pointer save/setup crypto/jitterentropy.o: warning: objtool: jent_entropy_collector_free()+0x19: call without frame pointer save/setup and arch/x86/events/core.o: warning: objtool: collect_events uses BP as a scratch register arch/x86/events/core.o: warning: objtool: events_ht_sysfs_show()+0x22: call without frame pointer save/setup With certain rare configurations, GCC sometimes sets up the frame pointer with: lea (%rsp),%rbp instead of: mov %rsp,%rbp The instructions are equivalent, so treat the former like the latter. Reported-by: Arnd Bergmann Signed-off-by: Josh Poimboeuf Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/a468af8b28a69b83fffc6d7668be9b6fcc873699.1506526584.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar

objtool: Handle another GCC stack pointer adjustment bug

2017-09-23T13:06:19Z

The kbuild bot reported the following warning with GCC 4.4 and a randconfig: net/socket.o: warning: objtool: compat_sock_ioctl()+0x1083: stack state mismatch: cfa1=7+160 cfa2=-1+0 This is caused by another GCC non-optimization, where it backs up and restores the stack pointer for no apparent reason: 2f91: 48 89 e0 mov %rsp,%rax 2f94: 4c 89 e7 mov %r12,%rdi 2f97: 4c 89 f6 mov %r14,%rsi 2f9a: ba 20 00 00 00 mov $0x20,%edx 2f9f: 48 89 c4 mov %rax,%rsp This issue would have been happily ignored before the following commit: dd88a0a0c861 ("objtool: Handle GCC stack pointer adjustment bug") But now that objtool is paying attention to such stack pointer writes to/from a register, it needs to understand them properly. In this case that means recognizing that the "mov %rsp, %rax" instruction is potentially a backup of the stack pointer. Reported-by: kbuild test robot Signed-off-by: Josh Poimboeuf Cc: Alexander Potapenko Cc: Andrey Ryabinin Cc: Andy Lutomirski Cc: Arnd Bergmann Cc: Dmitriy Vyukov Cc: Linus Torvalds Cc: Matthias Kaehlcke Cc: Miguel Bernal Marin Cc: Peter Zijlstra Cc: Thomas Gleixner Fixes: dd88a0a0c861 ("objtool: Handle GCC stack pointer adjustment bug") Link: http://lkml.kernel.org/r/8c7aa8e9a36fbbb6655d9d8e7cea58958c912da8.1505942196.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar

objtool: Handle GCC stack pointer adjustment bug

2017-08-30T08:48:41Z

Arnd Bergmann reported the following warning with GCC 7.1.1: fs/fs_pin.o: warning: objtool: pin_kill()+0x139: stack state mismatch: cfa1=7+88 cfa2=7+96 And the kbuild robot reported the following warnings with GCC 5.4.1: fs/fs_pin.o: warning: objtool: pin_kill()+0x182: return with modified stack frame fs/quota/dquot.o: warning: objtool: dquot_alloc_inode()+0x140: stack state mismatch: cfa1=7+120 cfa2=7+128 fs/quota/dquot.o: warning: objtool: dquot_free_inode()+0x11a: stack state mismatch: cfa1=7+112 cfa2=7+120 Those warnings are caused by an unusual GCC non-optimization where it uses an intermediate register to adjust the stack pointer. It does: lea 0x8(%rsp), %rcx ... mov %rcx, %rsp Instead of the obvious: add $0x8, %rsp It makes no sense to use an intermediate register, so I opened a GCC bug to track it: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81813 But it's not exactly a high-priority bug and it looks like we'll be stuck with this issue for a while. So for now we have to track register values when they're loaded with stack pointer offsets. This is kind of a big workaround for a tiny problem, but c'est la vie. I hope to eventually create a GCC plugin to implement a big chunk of objtool's functionality. Hopefully at that point we'll be able to remove of a lot of these GCC-isms from the objtool code. Reported-by: Arnd Bergmann Reported-by: kbuild test robot Signed-off-by: Josh Poimboeuf Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/6a41a96884c725e7f05413bb7df40cfe824b2444.1504028945.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar

objtool: Fix '-mtune=atom' decoding support in objtool 2.0

2017-07-28T06:33:32Z

With '-mtune=atom', which is enabled with CONFIG_MATOM=y, GCC uses some unusual instructions for setting up the stack. Instead of: mov %rsp, %rbp it does: lea (%rsp), %rbp And instead of: add imm, %rsp it does: lea disp(%rsp), %rsp Add support for these instructions to the objtool decoder. Reported-by: Arnd Bergmann Signed-off-by: Josh Poimboeuf Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Fixes: baa41469a7b9 ("objtool: Implement stack validation 2.0") Link: http://lkml.kernel.org/r/4ea1db896e821226efe1f8e09f270771bde47e65.1501188854.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar

objtool: Assume unannotated UD2 instructions are dead ends

2017-07-28T06:33:32Z

Arnd reported some false positive warnings with GCC 7: drivers/hid/wacom_wac.o: warning: objtool: wacom_bpt3_touch()+0x2a5: stack state mismatch: cfa1=7+8 cfa2=6+16 drivers/iio/adc/vf610_adc.o: warning: objtool: vf610_adc_calculate_rates() falls through to next function vf610_adc_sample_set() drivers/pwm/pwm-hibvt.o: warning: objtool: hibvt_pwm_get_state() falls through to next function hibvt_pwm_remove() drivers/pwm/pwm-mediatek.o: warning: objtool: mtk_pwm_config() falls through to next function mtk_pwm_enable() drivers/spi/spi-bcm2835.o: warning: objtool: .text: unexpected end of section drivers/spi/spi-bcm2835aux.o: warning: objtool: .text: unexpected end of section drivers/watchdog/digicolor_wdt.o: warning: objtool: dc_wdt_get_timeleft() falls through to next function dc_wdt_restart() When GCC 7 detects a potential divide-by-zero condition, it sometimes inserts a UD2 instruction for the case where the divisor is zero, instead of letting the hardware trap on the divide instruction. Objtool doesn't consider UD2 to be fatal unless it's annotated with unreachable(). So it considers the GCC-generated UD2 to be non-fatal, and it tries to follow the control flow past the UD2 and gets confused. Previously, objtool *did* assume UD2 was always a dead end. That changed with the following commit: d1091c7fa3d5 ("objtool: Improve detection of BUG() and other dead ends") The motivation behind that change was that Peter was planning on using UD2 for __WARN(), which is *not* a dead end. However, it turns out that some emulators rely on UD2 being fatal, so he ended up using 'ud0' instead: 9a93848fe787 ("x86/debug: Implement __WARN() using UD0") For GCC 4.5+, it should be safe to go back to the previous assumption that UD2 is fatal, even when it's not annotated with unreachable(). But for pre-4.5 versions of GCC, the unreachable() macro isn't supported, so such cases of UD2 need to be explicitly annotated as reachable. Reported-by: Arnd Bergmann Signed-off-by: Josh Poimboeuf Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Fixes: d1091c7fa3d5 ("objtool: Improve detection of BUG() and other dead ends") Link: http://lkml.kernel.org/r/e57fa9dfede25f79487da8126ee9cdf7b856db65.1501188854.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar

objtool: Implement stack validation 2.0

2017-06-30T08:19:19Z

This is a major rewrite of objtool. Instead of only tracking frame pointer changes, it now tracks all stack-related operations, including all register saves/restores. In addition to making stack validation more robust, this also paves the way for undwarf generation. Signed-off-by: Josh Poimboeuf Cc: Andy Lutomirski Cc: Jiri Slaby Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: live-patching@vger.kernel.org Link: http://lkml.kernel.org/r/678bd94c0566c6129bcc376cddb259c4c5633004.1498659915.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar

objtool: Improve detection of BUG() and other dead ends

2017-02-24T08:10:52Z

The BUG() macro's use of __builtin_unreachable() via the unreachable() macro tells gcc that the instruction is a dead end, and that it's safe to assume the current code path will not execute past the previous instruction. On x86, the BUG() macro is implemented with the 'ud2' instruction. When objtool's branch analysis sees that instruction, it knows the current code path has come to a dead end. Peter Zijlstra has been working on a patch to change the WARN macros to use 'ud2'. That patch will break objtool's assumption that 'ud2' is always a dead end. Generally it's best for objtool to avoid making those kinds of assumptions anyway. The more ignorant it is of kernel code internals, the better. So create a more generic way for objtool to detect dead ends by adding an annotation to the unreachable() macro. The annotation stores a pointer to the end of the unreachable code path in an '__unreachable' section. Objtool can read that section to find the dead ends. Tested-by: Peter Zijlstra (Intel) Signed-off-by: Josh Poimboeuf Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/41a6d33971462ebd944a1c60ad4bf5be86c17b77.1487712920.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar

objtool: Fix IRET's opcode

2017-01-19T07:39:44Z

The IRET opcode is 0xcf according to the Intel manual and also to objdump of my vmlinux: 1ea8: 48 cf iretq Fix the opcode in arch_decode_instruction(). The previous value (0xc5) seems to correspond to LDS. Signed-off-by: Jiri Slaby Acked-by: Josh Poimboeuf Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/20170118132921.19319-1-jslaby@suse.cz Signed-off-by: Ingo Molnar