kernel/linux.git/arch/arm/lib/memset.S, branch v6.18.22

ARM: 9321/1: memset: cast the constant byte to unsigned char

2023-10-05T15:15:41+00:00

memset() description in ISO/IEC 9899:1999 (and elsewhere) says: The memset function copies the value of c (converted to an unsigned char) into each of the first n characters of the object pointed to by s. The kernel's arm32 memset does not cast c to unsigned char. This results in the following code to produce erroneous output: char a[128]; memset(a, -128, sizeof(a)); This is because gcc will generally emit the following code before it calls memset() : mov r0, r7 mvn r1, #127 ; 0x7f bl 00000000 r1 ends up with 0xffffff80 before being used by memset() and the 'a' array will have -128 once in every four bytes while the other bytes will be set incorrectly to -1 like this (printing the first 8 bytes) : test_module: -128 -1 -1 -1 test_module: -1 -1 -1 -128 The change here is to 'and' r1 with 255 before it is used. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reviewed-by: Ard Biesheuvel Reviewed-by: Linus Walleij Signed-off-by: Kursad Oney Signed-off-by: Russell King (Oracle)

ARM: memset: clean up unwind annotations

2021-12-03T14:11:32+00:00

The memset implementation carves up the code in different sections, each covered with their own unwind info. In this case, it is done in a way similar to how the compiler might do it, to disambiguate between parts where the return address is in LR and the SP is unmodified, and parts where a stack frame is live, and the unwinder needs to know the size of the stack frame and the location of the return address within it. Only the placement of the unwind directives is slightly odd: the stack pushes are placed in the wrong sections, which may confuse the unwinder when attempting to unwind with PC pointing at the stack push in question. So let's fix this up, by reordering the directives and instructions as appropriate. Signed-off-by: Ard Biesheuvel Tested-by: Keith Packard Tested-by: Marc Zyngier Tested-by: Vladimir Murzin # ARMv7M

ARM: 9022/1: Change arch/arm/lib/mem*.S to use WEAK instead of .weak

2020-11-12T14:53:19+00:00

Commit d6d51a96c7d6 ("ARM: 9014/2: Replace string mem* functions for KASan") add .weak directives to memcpy/memmove/memset to avoid collision with KASAN interceptors. This does not work with LLVM's integrated assembler (the assembly snippet `.weak memcpy ... .globl memcpy` produces a STB_GLOBAL memcpy while GNU as produces a STB_WEAK memcpy). LLVM 12 (since https://reviews.llvm.org/D90108) will error on such an overridden symbol binding. Use the appropriate WEAK macro instead. Link: https://github.com/ClangBuiltLinux/linux/issues/1190 -- Fixes: d6d51a96c7d6 ("ARM: 9014/2: Replace string mem* functions for KASan") Reported-by: Nick Desaulniers Signed-off-by: Fangrui Song Reviewed-by: Nick Desaulniers Tested-by: Nick Desaulniers Signed-off-by: Russell King

ARM: 9014/2: Replace string mem* functions for KASan

2020-10-27T12:11:06+00:00

Functions like memset()/memmove()/memcpy() do a lot of memory accesses. If a bad pointer is passed to one of these functions it is important to catch this. Compiler instrumentation cannot do this since these functions are written in assembly. KASan replaces these memory functions with instrumented variants. The original functions are declared as weak symbols so that the strong definitions in mm/kasan/kasan.c can replace them. The original functions have aliases with a '__' prefix in their name, so we can call the non-instrumented variant if needed. We must use __memcpy()/__memset() in place of memcpy()/memset() when we copy .data to RAM and when we clear .bss, because kasan_early_init cannot be called before the initialization of .data and .bss. For the kernel compression and EFI libstub's custom string libraries we need a special quirk: even if these are built without KASan enabled, they rely on the global headers for their custom string libraries, which means that e.g. memcpy() will be defined to __memcpy() and we get link failures. Since these implementations are written i C rather than assembly we use e.g. __alias(memcpy) to redirected any users back to the local implementation. Cc: Andrey Ryabinin Cc: Alexander Potapenko Cc: Dmitry Vyukov Cc: kasan-dev@googlegroups.com Reviewed-by: Ard Biesheuvel Tested-by: Ard Biesheuvel # QEMU/KVM/mach-virt/LPAE/8G Tested-by: Florian Fainelli # Brahma SoCs Tested-by: Ahmad Fatoum # i.MX6Q Reported-by: Russell King - ARM Linux Signed-off-by: Ahmad Fatoum Signed-off-by: Abbott Liu Signed-off-by: Florian Fainelli Signed-off-by: Linus Walleij Signed-off-by: Russell King

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500

2019-06-19T15:09:55+00:00

Based on 2 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of the gnu general public license version 2 as published by the free software foundation this program is free software you can redistribute it and or modify it under the terms of the gnu general public license version 2 as published by the free software foundation # extracted by the scancode license scanner the SPDX license identifier GPL-2.0-only has been chosen to replace the boilerplate/reference in 4122 file(s). Signed-off-by: Thomas Gleixner Reviewed-by: Enrico Weigelt Reviewed-by: Kate Stewart Reviewed-by: Allison Randal Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190604081206.933168790@linutronix.de Signed-off-by: Greg Kroah-Hartman

ARM: 8844/1: use unified assembler in assembly files

2019-02-26T11:26:07+00:00

Use unified assembler syntax (UAL) in assembly files. Divided syntax is considered deprecated. This will also allow to build the kernel using LLVM's integrated assembler. Signed-off-by: Stefan Agner Acked-by: Nicolas Pitre Signed-off-by: Russell King

ARM: implement memset32 & memset64

2017-09-09T01:26:48+00:00

Reuse the existing optimised memset implementation to implement an optimised memset32 and memset64. Link: http://lkml.kernel.org/r/20170720184539.31609-5-willy@infradead.org Signed-off-by: Matthew Wilcox Reviewed-by: Russell King Cc: "H. Peter Anvin" Cc: "James E.J. Bottomley" Cc: "Martin K. Petersen" Cc: David Miller Cc: Ingo Molnar Cc: Ivan Kokshaysky Cc: Matt Turner Cc: Michael Ellerman Cc: Minchan Kim Cc: Ralf Baechle Cc: Richard Henderson Cc: Sam Ravnborg Cc: Sergey Senozhatsky Cc: Thomas Gleixner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Revert "arm: move exports to definitions"

2016-11-23T10:00:03+00:00

This reverts commit 4dd1837d7589f468ed109556513f476e7a7f9121. Moving the exports for assembly code into the assembly files breaks KSYM trimming, but also breaks modversions. While fixing the KSYM trimming is trivial, fixing modversions brings us to a technically worse position that we had prior to the above change: - We end up with the prototype definitions divorsed from everything else, which means that adding or removing assembly level ksyms become more fragile: * if adding a new assembly ksyms export, a missed prototype in asm-prototypes.h results in a successful build if no module in the selected configuration makes use of the symbol. * when removing a ksyms export, asm-prototypes.h will get forgotten, with armksyms.c, you'll get a build error if you forget to touch the file. - We end up with the same amount of include files and prototypes, they're just in a header file instead of a .c file with their exports. As for lines of code, we don't get much of a size reduction: (original commit) 47 files changed, 131 insertions(+), 208 deletions(-) (fix for ksyms trimming) 7 files changed, 18 insertions(+), 5 deletions(-) (two fixes for modversions) 1 file changed, 34 insertions(+) 3 files changed, 7 insertions(+), 2 deletions(-) which results in a net total of only 25 lines deleted. As there does not seem to be much benefit from this change of approach, revert the change. Signed-off-by: Russell King

arm: move exports to definitions

2016-08-08T03:47:21+00:00

Signed-off-by: Al Viro

ARM: avoid unwanted GCC memset()/memcpy() optimisations for IO variants

2015-07-03T19:46:15+00:00

We don't want GCC optimising our memset_io(), memcpy_fromio() or memcpy_toio() variants, so we must not call one of the standard functions. Provide a separate name for our assembly memcpy() and memset() functions, and use that instead, thereby bypassing GCC's ability to optimise these operations. GCCs optimisation may introduce unaligned accesses which are invalid for device mappings. Signed-off-by: Russell King