kernel/linux.git/include/linux/compiler_attributes.h, branch v6.4-rc6

Remove Intel compiler support

2023-03-05T18:49:37+00:00

include/linux/compiler-intel.h had no update in the past 3 years. We often forget about the third C compiler to build the kernel. For example, commit a0a12c3ed057 ("asm goto: eradicate CC_HAS_ASM_GOTO") only mentioned GCC and Clang. init/Kconfig defines CC_IS_GCC and CC_IS_CLANG but not CC_IS_ICC, and nobody has reported any issue. I guess the Intel Compiler support is broken, and nobody is caring about it. Harald Arnesen pointed out ICC (classic Intel C/C++ compiler) is deprecated: $ icc -v icc: remark #10441: The Intel(R) C++ Compiler Classic (ICC) is deprecated and will be removed from product release in the second half of 2023. The Intel(R) oneAPI DPC++/C++ Compiler (ICX) is the recommended compiler moving forward. Please transition to use this compiler. Use '-diag-disable=10441' to disable this message. icc version 2021.7.0 (gcc version 12.1.0 compatibility) Arnd Bergmann provided a link to the article, "Intel C/C++ compilers complete adoption of LLVM". lib/zstd/common/compiler.h and lib/zstd/compress/zstd_fast.c were kept untouched for better sync with https://github.com/facebook/zstd Link: https://www.intel.com/content/www/us/en/developer/articles/technical/adoption-of-llvm-complete-icx.html Signed-off-by: Masahiro Yamada Acked-by: Arnd Bergmann Reviewed-by: Nick Desaulniers Reviewed-by: Nathan Chancellor Reviewed-by: Miguel Ojeda Signed-off-by: Linus Torvalds

Merge tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux

2023-02-21T23:27:48+00:00

Pull arm64 updates from Catalin Marinas: - Support for arm64 SME 2 and 2.1. SME2 introduces a new 512-bit architectural register (ZT0, for the look-up table feature) that Linux needs to save/restore - Include TPIDR2 in the signal context and add the corresponding kselftests - Perf updates: Arm SPEv1.2 support, HiSilicon uncore PMU updates, ACPI support to the Marvell DDR and TAD PMU drivers, reset DTM_PMU_CONFIG (ARM CMN) at probe time - Support for DYNAMIC_FTRACE_WITH_CALL_OPS on arm64 - Permit EFI boot with MMU and caches on. Instead of cleaning the entire loaded kernel image to the PoC and disabling the MMU and caches before branching to the kernel bare metal entry point, leave the MMU and caches enabled and rely on EFI's cacheable 1:1 mapping of all of system RAM to populate the initial page tables - Expose the AArch32 (compat) ELF_HWCAP features to user in an arm64 kernel (the arm32 kernel only defines the values) - Harden the arm64 shadow call stack pointer handling: stash the shadow stack pointer in the task struct on interrupt, load it directly from this structure - Signal handling cleanups to remove redundant validation of size information and avoid reading the same data from userspace twice - Refactor the hwcap macros to make use of the automatically generated ID registers. It should make new hwcaps writing less error prone - Further arm64 sysreg conversion and some fixes - arm64 kselftest fixes and improvements - Pointer authentication cleanups: don't sign leaf functions, unify asm-arch manipulation - Pseudo-NMI code generation optimisations - Minor fixes for SME and TPIDR2 handling - Miscellaneous updates: ARCH_FORCE_MAX_ORDER is now selectable, replace strtobool() to kstrtobool() in the cpufeature.c code, apply dynamic shadow call stack in two passes, intercept pfn changes in set_pte_at() without the required break-before-make sequence, attempt to dump all instructions on unhandled kernel faults * tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: (130 commits) arm64: fix .idmap.text assertion for large kernels kselftest/arm64: Don't require FA64 for streaming SVE+ZA tests kselftest/arm64: Copy whole EXTRA context arm64: kprobes: Drop ID map text from kprobes blacklist perf: arm_spe: Print the version of SPE detected perf: arm_spe: Add support for SPEv1.2 inverted event filtering perf: Add perf_event_attr::config3 arm64/sme: Fix __finalise_el2 SMEver check drivers/perf: fsl_imx8_ddr_perf: Remove set-but-not-used variable arm64/signal: Only read new data when parsing the ZT context arm64/signal: Only read new data when parsing the ZA context arm64/signal: Only read new data when parsing the SVE context arm64/signal: Avoid rereading context frame sizes arm64/signal: Make interface for restore_fpsimd_context() consistent arm64/signal: Remove redundant size validation from parse_user_sigframe() arm64/signal: Don't redundantly verify FPSIMD magic arm64/cpufeature: Use helper macros to specify hwcaps arm64/cpufeature: Always use symbolic name for feature value in hwcaps arm64/sysreg: Initial unsigned annotations for ID registers arm64/sysreg: Initial annotation of signed ID registers ...

Compiler attributes: GCC cold function alignment workarounds

2023-01-24T11:49:42+00:00

Contemporary versions of GCC (e.g. GCC 12.2.0) drop the alignment specified by '-falign-functions=N' for functions marked with the __cold__ attribute, and potentially for callees of __cold__ functions as these may be implicitly marked as __cold__ by the compiler. LLVM appears to respect '-falign-functions=N' in such cases. This has been reported to GCC in bug 88345: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88345 ... which also covers alignment being dropped when '-Os' is used, which will be addressed in a separate patch. Currently, use of '-falign-functions=N' is limited to CONFIG_FUNCTION_ALIGNMENT, which is largely used for performance and/or analysis reasons (e.g. with CONFIG_DEBUG_FORCE_FUNCTION_ALIGN_64B), but isn't necessary for correct functionality. However, this dropped alignment isn't great for the performance and/or analysis cases. Subsequent patches will use CONFIG_FUNCTION_ALIGNMENT as part of arm64's ftrace implementation, which will require all instrumented functions to be aligned to at least 8-bytes. This patch works around the dropped alignment by avoiding the use of the __cold__ attribute when CONFIG_FUNCTION_ALIGNMENT is non-zero, and by specifically aligning abort(), which GCC implicitly marks as __cold__. As the __cold macro is now dependent upon config options (which is against the policy described at the top of compiler_attributes.h), it is moved into compiler_types.h. I've tested this by building and booting a kernel configured with defconfig + CONFIG_EXPERT=y + CONFIG_DEBUG_FORCE_FUNCTION_ALIGN_64B=y, and looking for misaligned text symbols in /proc/kallsyms: * arm64: Before: # uname -rm 6.2.0-rc3 aarch64 # grep ' [Tt] ' /proc/kallsyms | grep -iv '[048c]0 [Tt] ' | wc -l 5009 After: # uname -rm 6.2.0-rc3-00001-g2a2bedf8bfa9 aarch64 # grep ' [Tt] ' /proc/kallsyms | grep -iv '[048c]0 [Tt] ' | wc -l 919 * x86_64: Before: # uname -rm 6.2.0-rc3 x86_64 # grep ' [Tt] ' /proc/kallsyms | grep -iv '[048c]0 [Tt] ' | wc -l 11537 After: # uname -rm 6.2.0-rc3-00001-g2a2bedf8bfa9 x86_64 # grep ' [Tt] ' /proc/kallsyms | grep -iv '[048c]0 [Tt] ' | wc -l 2805 There's clearly a substantial reduction in the number of misaligned symbols. From manual inspection, the remaining unaligned text labels are a combination of ACPICA functions (due to the use of '-Os'), static call trampolines, and non-function labels in assembly, which will be dealt with in subsequent patches. Signed-off-by: Mark Rutland Cc: Florent Revest Cc: Masami Hiramatsu Cc: Peter Zijlstra Cc: Steven Rostedt Cc: Will Deacon Cc: Miguel Ojeda Cc: Nick Desaulniers Link: https://lore.kernel.org/r/20230123134603.1064407-3-mark.rutland@arm.com Signed-off-by: Catalin Marinas

fortify: Use __builtin_dynamic_object_size() when available

2023-01-05T20:08:29+00:00

Since the commits starting with c37495d6254c ("slab: add __alloc_size attributes for better bounds checking"), the compilers have runtime allocation size hints available in some places. This was immediately available to CONFIG_UBSAN_BOUNDS, but CONFIG_FORTIFY_SOURCE needed updating to explicitly make use of the hints via the associated __builtin_dynamic_object_size() helper. Detect and use the builtin when it is available, increasing the accuracy of the mitigation. When runtime sizes are not available, __builtin_dynamic_object_size() falls back to __builtin_object_size(), leaving the existing bounds checking unchanged. Additionally update the VMALLOC_LINEAR_OVERFLOW LKDTM test to make the hint invisible, otherwise the architectural defense is not exercised (the buffer overflow is detected in the memset() rather than when it crosses the edge of the allocation). Cc: Arnd Bergmann Cc: Greg Kroah-Hartman Cc: Nick Desaulniers Cc: Nathan Chancellor Cc: Tom Rix Cc: linux-hardening@vger.kernel.org Cc: llvm@lists.linux.dev Reviewed-by: Miguel Ojeda # include/linux/compiler_attributes.h Signed-off-by: Kees Cook

Merge tag 'slab-for-6.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/vbabka/slab

2022-10-10T17:21:22+00:00

Pull slab fixes from Vlastimil Babka: - The "common kmalloc v4" series [1] by Hyeonggon Yoo. While the plan after LPC is to try again if it's possible to get rid of SLOB and SLAB (and if any critical aspect of those is not possible to achieve with SLUB today, modify it accordingly), it will take a while even in case there are no objections. Meanwhile this is a nice cleanup and some parts (e.g. to the tracepoints) will be useful even if we end up with a single slab implementation in the future: - Improves the mm/slab_common.c wrappers to allow deleting duplicated code between SLAB and SLUB. - Large kmalloc() allocations in SLAB are passed to page allocator like in SLUB, reducing number of kmalloc caches. - Removes the {kmem_cache_alloc,kmalloc}_node variants of tracepoints, node id parameter added to non-_node variants. - Addition of kmalloc_size_roundup() The first two patches from a series by Kees Cook [2] that introduce kmalloc_size_roundup(). This will allow merging of per-subsystem patches using the new function and ultimately stop (ab)using ksize() in a way that causes ongoing trouble for debugging functionality and static checkers. - Wasted kmalloc() memory tracking in debugfs alloc_traces A patch from Feng Tang that enhances the existing debugfs alloc_traces file for kmalloc caches with information about how much space is wasted by allocations that needs less space than the particular kmalloc cache provides. - My series [3] to fix validation races for caches with enabled debugging: - By decoupling the debug cache operation more from non-debug fastpaths, extra locking simplifications were possible and thus done afterwards. - Additional cleanup of PREEMPT_RT specific code on top, by Thomas Gleixner. - A late fix for slab page leaks caused by the series, by Feng Tang. - Smaller fixes and cleanups: - Unneeded variable removals, by ye xingchen - A cleanup removing a BUG_ON() in create_unique_id(), by Chao Yu Link: https://lore.kernel.org/all/20220817101826.236819-1-42.hyeyoo@gmail.com/ [1] Link: https://lore.kernel.org/all/20220923202822.2667581-1-keescook@chromium.org/ [2] Link: https://lore.kernel.org/all/20220823170400.26546-1-vbabka@suse.cz/ [3] * tag 'slab-for-6.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/vbabka/slab: (30 commits) mm/slub: fix a slab missed to be freed problem slab: Introduce kmalloc_size_roundup() slab: Remove __malloc attribute from realloc functions mm/slub: clean up create_unique_id() mm/slub: enable debugging memory wasting of kmalloc slub: Make PREEMPT_RT support less convoluted mm/slub: simplify __cmpxchg_double_slab() and slab_[un]lock() mm/slub: convert object_map_lock to non-raw spinlock mm/slub: remove slab_lock() usage for debug operations mm/slub: restrict sysfs validation to debug caches and make it safe mm/sl[au]b: check if large object is valid in __ksize() mm/slab_common: move declaration of __ksize() to mm/slab.h mm/slab_common: drop kmem_alloc & avoid dereferencing fields when not using mm/slab_common: unify NUMA and UMA version of tracepoints mm/sl[au]b: cleanup kmem_cache_alloc[_node]_trace() mm/sl[au]b: generalize kmalloc subsystem mm/slub: move free_debug_processing() further mm/sl[au]b: introduce common alloc/free functions without tracepoint mm/slab: kmalloc: pass requests larger than order-1 page to page allocator mm/slab_common: cleanup kmalloc_large() ...

slab: Remove __malloc attribute from realloc functions

2022-09-29T09:05:57+00:00

The __malloc attribute should not be applied to "realloc" functions, as the returned pointer may alias the storage of the prior pointer. Instead of splitting __malloc from __alloc_size, which would be a huge amount of churn, just create __realloc_size for the few cases where it is needed. Thanks to Geert Uytterhoeven for reporting build failures with gcc-8 in earlier version which tried to remove the #ifdef. While the "alloc_size" attribute is available on all GCC versions, I forgot that it gets disabled explicitly by the kernel in GCC < 9.1 due to misbehaviors. Add a note to the compiler_attributes.h entry for it. Cc: Christoph Lameter Cc: Pekka Enberg Cc: David Rientjes Cc: Joonsoo Kim Cc: Andrew Morton Cc: Vlastimil Babka Cc: Roman Gushchin Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com> Cc: Marco Elver Cc: linux-mm@kvack.org Signed-off-by: Kees Cook Signed-off-by: Vlastimil Babka

net: skb: prevent the split of kfree_skb_reason() by gcc

2022-08-24T08:47:51+00:00

Sometimes, gcc will optimize the function by spliting it to two or more functions. In this case, kfree_skb_reason() is splited to kfree_skb_reason and kfree_skb_reason.part.0. However, the function/tracepoint trace_kfree_skb() in it needs the return address of kfree_skb_reason(). This split makes the call chains becomes: kfree_skb_reason() -> kfree_skb_reason.part.0 -> trace_kfree_skb() which makes the return address that passed to trace_kfree_skb() be kfree_skb(). Therefore, introduce '__fix_address', which is the combination of '__noclone' and 'noinline', and apply it to kfree_skb_reason() to prevent to from being splited or made inline. (Is it better to simply apply '__noclone oninline' to kfree_skb_reason? I'm thinking maybe other functions have the same problems) Meanwhile, wrap 'skb_unref()' with 'unlikely()', as the compiler thinks it is likely return true and splits kfree_skb_reason(). Signed-off-by: Menglong Dong Signed-off-by: David S. Miller

Compiler Attributes: Add __diagnose_as for Clang

2022-02-14T00:50:07+00:00

Clang will perform various compile-time diagnostics on uses of various functions (e.g. simple bounds-checking on strcpy(), etc). These diagnostics can be assigned to other functions (for example, new implementations of the string functions under CONFIG_FORTIFY_SOURCE) using the "diagnose_as_builtin" attribute. This allows those functions to retain their compile-time diagnostic warnings. Cc: Nathan Chancellor Cc: llvm@lists.linux.dev Reviewed-by: Miguel Ojeda Reviewed-by: Nick Desaulniers Signed-off-by: Kees Cook Link: https://lore.kernel.org/r/20220208225350.1331628-5-keescook@chromium.org

Compiler Attributes: Add __overloadable for Clang

2022-02-14T00:50:07+00:00

In order for FORTIFY_SOURCE to use __pass_object_size on an "extern inline" function, as all the fortified string functions are, the functions must be marked as being overloadable (i.e. different prototypes due to the implicitly injected object size arguments). This allows the __pass_object_size versions to take precedence. Cc: Nathan Chancellor Cc: llvm@lists.linux.dev Reviewed-by: Miguel Ojeda Reviewed-by: Nick Desaulniers Signed-off-by: Kees Cook Link: https://lore.kernel.org/r/20220208225350.1331628-4-keescook@chromium.org

Compiler Attributes: Add __pass_object_size for Clang

2022-02-14T00:50:06+00:00

In order to gain greater visibility to type information when using __builtin_object_size(), Clang has a function attribute "pass_object_size" that will make size information available for marked arguments in a function by way of implicit additional function arguments that are then wired up the __builtin_object_size(). This is needed to implement FORTIFY_SOURCE in Clang, as a workaround to Clang's __builtin_object_size() having limited visibility[1] into types across function calls (even inlines). This attribute has an additional benefit that it can be used even on non-inline functions to gain argument size information. [1] https://github.com/llvm/llvm-project/issues/53516 Cc: Nick Desaulniers Cc: Nathan Chancellor Cc: llvm@lists.linux.dev Reviewed-by: Miguel Ojeda Signed-off-by: Kees Cook Reviewed-by: Nick Desaulniers Link: https://lore.kernel.org/r/20220208225350.1331628-3-keescook@chromium.org