user/sven/linux.git/include/linux/compiler.h, branch v4.9.197

Backport minimal compiler_attributes.h to support GCC 9

2019-08-06T16:29:42Z

This adds support for __copy to v4.9.y so that we can use it in init/exit_module to avoid -Werror=missing-attributes errors on GCC 9. Link: https://lore.kernel.org/lkml/259986242.BvXPX32bHu@devpool35/ Cc: Suggested-by: Rolf Eike Beer Signed-off-by: Miguel Ojeda Signed-off-by: Greg Kroah-Hartman

compiler.h: Add read_word_at_a_time() function.

2019-08-04T07:33:32Z

[ Upstream commit 7f1e541fc8d57a143dd5df1d0a1276046e08c083 ] Sometimes we know that it's safe to do potentially out-of-bounds access because we know it won't cross a page boundary. Still, KASAN will report this as a bug. Add read_word_at_a_time() function which is supposed to be used in such cases. In read_word_at_a_time() KASAN performs relaxed check - only the first byte of access is validated. Signed-off-by: Andrey Ryabinin Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin

compiler.h, kasan: Avoid duplicating __read_once_size_nocheck()

2019-08-04T07:33:32Z

[ Upstream commit bdb5ac801af3d81d36732c2f640d6a1d3df83826 ] Instead of having two identical __read_once_size_nocheck() functions with different attributes, consolidate all the difference in new macro __no_kasan_or_inline and use it. No functional changes. Signed-off-by: Andrey Ryabinin Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin

bug.h: work around GCC PR82365 in BUG()

2019-07-10T07:55:44Z

[ Upstream commit 173a3efd3edb2ef6ef07471397c5f542a360e9c1 ] Looking at functions with large stack frames across all architectures led me discovering that BUG() suffers from the same problem as fortify_panic(), which I've added a workaround for already. In short, variables that go out of scope by calling a noreturn function or __builtin_unreachable() keep using stack space in functions afterwards. A workaround that was identified is to insert an empty assembler statement just before calling the function that doesn't return. I'm adding a macro "barrier_before_unreachable()" to document this, and insert calls to that in all instances of BUG() that currently suffer from this problem. The files that saw the largest change from this had these frame sizes before, and much less with my patch: fs/ext4/inode.c:82:1: warning: the frame size of 1672 bytes is larger than 800 bytes [-Wframe-larger-than=] fs/ext4/namei.c:434:1: warning: the frame size of 904 bytes is larger than 800 bytes [-Wframe-larger-than=] fs/ext4/super.c:2279:1: warning: the frame size of 1160 bytes is larger than 800 bytes [-Wframe-larger-than=] fs/ext4/xattr.c:146:1: warning: the frame size of 1168 bytes is larger than 800 bytes [-Wframe-larger-than=] fs/f2fs/inode.c:152:1: warning: the frame size of 1424 bytes is larger than 800 bytes [-Wframe-larger-than=] net/netfilter/ipvs/ip_vs_core.c:1195:1: warning: the frame size of 1068 bytes is larger than 800 bytes [-Wframe-larger-than=] net/netfilter/ipvs/ip_vs_core.c:395:1: warning: the frame size of 1084 bytes is larger than 800 bytes [-Wframe-larger-than=] net/netfilter/ipvs/ip_vs_ftp.c:298:1: warning: the frame size of 928 bytes is larger than 800 bytes [-Wframe-larger-than=] net/netfilter/ipvs/ip_vs_ftp.c:418:1: warning: the frame size of 908 bytes is larger than 800 bytes [-Wframe-larger-than=] net/netfilter/ipvs/ip_vs_lblcr.c:718:1: warning: the frame size of 960 bytes is larger than 800 bytes [-Wframe-larger-than=] drivers/net/xen-netback/netback.c:1500:1: warning: the frame size of 1088 bytes is larger than 800 bytes [-Wframe-larger-than=] In case of ARC and CRIS, it turns out that the BUG() implementation actually does return (or at least the compiler thinks it does), resulting in lots of warnings about uninitialized variable use and leaving noreturn functions, such as: block/cfq-iosched.c: In function 'cfq_async_queue_prio': block/cfq-iosched.c:3804:1: error: control reaches end of non-void function [-Werror=return-type] include/linux/dmaengine.h: In function 'dma_maxpq': include/linux/dmaengine.h:1123:1: error: control reaches end of non-void function [-Werror=return-type] This makes them call __builtin_trap() instead, which should normally dump the stack and kill the current process, like some of the other architectures already do. I tried adding barrier_before_unreachable() to panic() and fortify_panic() as well, but that had very little effect, so I'm not submitting that patch. Vineet said: : For ARC, it is double win. : : 1. Fixes 3 -Wreturn-type warnings : : | ../net/core/ethtool.c:311:1: warning: control reaches end of non-void function : [-Wreturn-type] : | ../kernel/sched/core.c:3246:1: warning: control reaches end of non-void function : [-Wreturn-type] : | ../include/linux/sunrpc/svc_xprt.h:180:1: warning: control reaches end of : non-void function [-Wreturn-type] : : 2. bloat-o-meter reports code size improvements as gcc elides the : generated code for stack return. Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82365 Link: http://lkml.kernel.org/r/20171219114112.939391-1-arnd@arndb.de Signed-off-by: Arnd Bergmann Acked-by: Vineet Gupta [arch/arc] Tested-by: Vineet Gupta [arch/arc] Cc: Mikael Starvik Cc: Jesper Nilsson Cc: Tony Luck Cc: Fenghua Yu Cc: Geert Uytterhoeven Cc: "David S. Miller" Cc: Christopher Li Cc: Thomas Gleixner Cc: Peter Zijlstra Cc: Kees Cook Cc: Ingo Molnar Cc: Josh Poimboeuf Cc: Will Deacon Cc: "Steven Rostedt (VMware)" Cc: Mark Rutland Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin [removed cris chunks - gregkh] Signed-off-by: Greg Kroah-Hartman

branch-check: fix long->int truncation when profiling branches

2018-07-03T09:23:07Z

commit 2026d35741f2c3ece73c11eb7e4a15d7c2df9ebe upstream. The function __builtin_expect returns long type (see the gcc documentation), and so do macros likely and unlikely. Unfortunatelly, when CONFIG_PROFILE_ANNOTATED_BRANCHES is selected, the macros likely and unlikely expand to __branch_check__ and __branch_check__ truncates the long type to int. This unintended truncation may cause bugs in various kernel code (we found a bug in dm-writecache because of it), so it's better to fix __branch_check__ to return long. Link: http://lkml.kernel.org/r/alpine.LRH.2.02.1805300818140.24812@file01.intranet.prod.int.rdu2.redhat.com Cc: Ingo Molnar Cc: stable@vger.kernel.org Fixes: 1f0d69a9fc815 ("tracing: profile likely and unlikely annotations") Signed-off-by: Mikulas Patocka Signed-off-by: Steven Rostedt (VMware) Signed-off-by: Greg Kroah-Hartman

compiler-gcc.h: Introduce __optimize function attribute

2018-02-22T14:43:53Z

commit df5d45aa08f848b79caf395211b222790534ccc7 upstream. Create a new function attribute __optimize, which allows to specify an optimization level on a per-function basis. Signed-off-by: Geert Uytterhoeven Acked-by: Ard Biesheuvel Signed-off-by: Herbert Xu Signed-off-by: Greg Kroah-Hartman

Merge tag 'gcc-plugins-v4.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

2016-10-15T17:03:15Z

Pull gcc plugins update from Kees Cook: "This adds a new gcc plugin named "latent_entropy". It is designed to extract as much possible uncertainty from a running system at boot time as possible, hoping to capitalize on any possible variation in CPU operation (due to runtime data differences, hardware differences, SMP ordering, thermal timing variation, cache behavior, etc). At the very least, this plugin is a much more comprehensive example for how to manipulate kernel code using the gcc plugin internals" * tag 'gcc-plugins-v4.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: latent_entropy: Mark functions with __latent_entropy gcc-plugins: Add latent_entropy plugin

Merge branch 'kbuild' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild

2016-10-14T21:26:58Z

Pull kbuild updates from Michal Marek: - EXPORT_SYMBOL for asm source by Al Viro. This does bring a regression, because genksyms no longer generates checksums for these symbols (CONFIG_MODVERSIONS). Nick Piggin is working on a patch to fix this. Plus, we are talking about functions like strcpy(), which rarely change prototypes. - Fixes for PPC fallout of the above by Stephen Rothwell and Nick Piggin - fixdep speedup by Alexey Dobriyan. - preparatory work by Nick Piggin to allow architectures to build with -ffunction-sections, -fdata-sections and --gc-sections - CONFIG_THIN_ARCHIVES support by Stephen Rothwell - fix for filenames with colons in the initramfs source by me. * 'kbuild' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild: (22 commits) initramfs: Escape colons in depfile ppc: there is no clear_pages to export powerpc/64: whitelist unresolved modversions CRCs kbuild: -ffunction-sections fix for archs with conflicting sections kbuild: add arch specific post-link Makefile kbuild: allow archs to select link dead code/data elimination kbuild: allow architectures to use thin archives instead of ld -r kbuild: Regenerate genksyms lexer kbuild: genksyms fix for typeof handling fixdep: faster CONFIG_ search ia64: move exports to definitions sparc32: debride memcpy.S a bit [sparc] unify 32bit and 64bit string.h sparc: move exports to definitions ppc: move exports to definitions arm: move exports to definitions s390: move exports to definitions m68k: move exports to definitions alpha: move exports to actual definitions x86: move exports to actual definitions ...

latent_entropy: Mark functions with __latent_entropy

2016-10-10T21:51:45Z

The __latent_entropy gcc attribute can be used only on functions and variables. If it is on a function then the plugin will instrument it for gathering control-flow entropy. If the attribute is on a variable then the plugin will initialize it with random contents. The variable must be an integer, an integer array type or a structure with integer fields. These specific functions have been selected because they are init functions (to help gather boot-time entropy), are called at unpredictable times, or they have variable loops, each of which provide some level of latent entropy. Signed-off-by: Emese Revfy [kees: expanded commit message] Signed-off-by: Kees Cook

kbuild: allow archs to select link dead code/data elimination

2016-09-09T08:47:00Z

Introduce LD_DEAD_CODE_DATA_ELIMINATION option for architectures to select to build with -ffunction-sections, -fdata-sections, and link with --gc-sections. It requires some work (documented) to ensure all unreferenced entrypoints are live, and requires toolchain and build verification, so it is made a per-arch option for now. On a random powerpc64le build, this yelds a significant size saving, it boots and runs fine, but there is a lot I haven't tested as yet, so these savings may be reduced if there are bugs in the link. text data bss dec filename 11169741 1180744 1923176 14273661 vmlinux 10445269 1004127 1919707 13369103 vmlinux.dce ~700K text, ~170K data, 6% removed from kernel image size. Signed-off-by: Nicholas Piggin Signed-off-by: Michal Marek