kernel/linux.git/include/linux/bitfield.h, branch v6.6.132

bitfield: add FIELD_PREP_CONST()

2023-01-19T13:46:25+00:00

Neither FIELD_PREP() nor *_encode_bits() can be used in constant contexts (such as initializers), but we don't want to define shift constants for all masks just for use in initializers, and having checks that the values fit is also useful. Therefore, add FIELD_PREP_CONST() which is a smaller version of FIELD_PREP() that can only take constant arguments and has less friendly (but not less strict) error checks, and expands to a constant value. Signed-off-by: Johannes Berg Link: https://lore.kernel.org/r/20230118142652.53f20593504b.Iaeea0aee77a6493d70e573b4aa55c91c00e01e4b@changeid Signed-off-by: Johannes Berg

bitfield: add explicit inclusions to the example

2022-03-24T02:00:33+00:00

It's not obvious that bitfield.h doesn't guarantee the bits.h inclusion and the example in the former is confusing. Some developers think that it's okay to just include bitfield.h to get it working. Change example to explicitly include necessary headers in order to avoid confusion. Link: https://lkml.kernel.org/r/20220207123341.47533-1-andriy.shevchenko@linux.intel.com Fixes: 3e9b3112ec74 ("add basic register-field manipulation macros") Depends-on: 8bd9cb51daac ("locking/atomics, asm-generic: Move some macros from to a new file") Signed-off-by: Andy Shevchenko Reported-by: Jan Dąbroś Cc: Peter Zijlstra Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

bitfield.h: Fix "type of reg too small for mask" test

2021-12-11T08:09:45+00:00

The test: 'mask > (typeof(_reg))~0ull' only works correctly when both sides are unsigned, consider: - 0xff000000 vs (int)~0ull - 0x000000ff vs (int)~0ull Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Josh Poimboeuf Link: https://lore.kernel.org/r/20211110101324.950210584@infradead.org

bitfield.h: don't compile-time validate _val in FIELD_FIT

2020-08-10T19:16:51+00:00

When ur_load_imm_any() is inlined into jeq_imm(), it's possible for the compiler to deduce a case where _val can only have the value of -1 at compile time. Specifically, /* struct bpf_insn: _s32 imm */ u64 imm = insn->imm; /* sign extend */ if (imm >> 32) { /* non-zero only if insn->imm is negative */ /* inlined from ur_load_imm_any */ u32 __imm = imm >> 32; /* therefore, always 0xffffffff */ if (__builtin_constant_p(__imm) && __imm > 255) compiletime_assert_XXX() This can result in tripping a BUILD_BUG_ON() in __BF_FIELD_CHECK() that checks that a given value is representable in one byte (interpreted as unsigned). FIELD_FIT() should return true or false at runtime for whether a value can fit for not. Don't break the build over a value that's too large for the mask. We'd prefer to keep the inlining and compiler optimizations though we know this case will always return false. Cc: stable@vger.kernel.org Fixes: 1697599ee301a ("bitfield.h: add FIELD_FIT() helper") Link: https://lore.kernel.org/kernel-hardening/CAK7LNASvb0UDJ0U5wkYYRzTAdnEs64HjXpEUL7d=V0CXiAXcNw@mail.gmail.com/ Reported-by: Masahiro Yamada Debugged-by: Sami Tolvanen Signed-off-by: Jakub Kicinski Signed-off-by: Nick Desaulniers Signed-off-by: David S. Miller

bitfield.h: add FIELD_MAX() and field_max()

2020-03-12T22:48:37+00:00

Define FIELD_MAX(), which supplies the maximum value that can be represented by a field value. Define field_max() as well, to go along with the lower-case forms of the field mask functions. Signed-off-by: Alex Elder Acked-by: Jakub Kicinski Signed-off-by: David S. Miller

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 174

2019-05-30T18:26:41+00:00

Based on 1 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 distributed in the hope that it will be useful but without any warranty without even the implied warranty of merchantability or fitness for a particular purpose see the gnu general public license for more details extracted by the scancode license scanner the SPDX license identifier GPL-2.0-only has been chosen to replace the boilerplate/reference in 655 file(s). Signed-off-by: Thomas Gleixner Reviewed-by: Allison Randal Reviewed-by: Kate Stewart Reviewed-by: Richard Fontana Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190527070034.575739538@linutronix.de Signed-off-by: Greg Kroah-Hartman

bitfield: avoid gcc-8 -Wint-in-bool-context warning

2018-08-17T23:20:27+00:00

Passing an enum into FIELD_GET() produces a long but harmless warning on newer compilers: from include/linux/linkage.h:7, from include/linux/kernel.h:7, from include/linux/skbuff.h:17, from include/linux/if_ether.h:23, from include/linux/etherdevice.h:25, from drivers/net/wireless/intel/iwlwifi/mvm/rxmq.c:63: drivers/net/wireless/intel/iwlwifi/mvm/rxmq.c: In function 'iwl_mvm_rx_mpdu_mq': include/linux/bitfield.h:56:20: error: enum constant in boolean context [-Werror=int-in-bool-context] BUILD_BUG_ON_MSG(!(_mask), _pfx "mask is zero"); \ ^ ... include/linux/bitfield.h:103:3: note: in expansion of macro '__BF_FIELD_CHECK' __BF_FIELD_CHECK(_mask, _reg, 0U, "FIELD_GET: "); \ ^~~~~~~~~~~~~~~~ drivers/net/wireless/intel/iwlwifi/mvm/rxmq.c:1025:21: note: in expansion of macro 'FIELD_GET' le16_encode_bits(FIELD_GET(IWL_RX_HE_PHY_SIBG_SYM_OR_USER_NUM_MASK, The problem here is that the caller has no idea how the macro gets expanding, leading to a false-positive. It can be trivially avoided by doing a comparison against zero. This only recently started appearing as the iwlwifi driver was patched to use FIELD_GET. Link: http://lkml.kernel.org/r/20180813220950.194841-1-arnd@arndb.de Fixes: 514c30696fbc ("iwlwifi: add support for IEEE802.11ax") Signed-off-by: Arnd Bergmann Cc: Masahiro Yamada Cc: Johannes Berg Cc: Jakub Kicinski Cc: Andy Shevchenko Cc: Al Viro Cc: David Laight Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

bitfield: add u8 helpers

2018-06-27T15:58:49+00:00

There's no reason why we shouldn't pack/unpack bits into/from u8 values/registers/etc., so add u8 helpers. Use the ____MAKE_OP() macro directly to avoid having nonsense le8_encode_bits() and similar functions. Reviewed-by: Andy Shevchenko Signed-off-by: Johannes Berg Signed-off-by: Kalle Valo

bitfield: fix *_encode_bits()

2018-06-27T15:58:48+00:00

There's a bug in *_encode_bits() in using ~field_multiplier() for the check whether or not the constant value fits into the field, this is wrong and clearly ~field_mask() was intended. This was triggering for me for both constant and non-constant values. Additionally, make this case actually into an compile error. Declaring the extern function that will never exist with just a warning is pointless as then later we'll just get a link error. While at it, also fix the indentation in those lines I'm touching. Finally, as suggested by Andy Shevchenko, add some tests and for that introduce also u8 helpers. The tests don't compile without the fix, showing that it's necessary. Fixes: 00b0c9b82663 ("Add primitives for manipulating bitfields both in host- and fixed-endian.") Reviewed-by: Andy Shevchenko Signed-off-by: Johannes Berg Signed-off-by: Kalle Valo

Add primitives for manipulating bitfields both in host- and fixed-endian.

2017-12-17T17:36:01+00:00

The following primitives are defined in linux/bitfield.h: * u32 le32_get_bits(__le32 val, u32 field) extracts the contents of the bitfield specified by @field in little-endian 32bit object @val and converts it to host-endian. * void le32p_replace_bits(__le32 *p, u32 v, u32 field) replaces the contents of the bitfield specified by @field in little-endian 32bit object pointed to by @p with the value of @v. New value is given in host-endian and stored as little-endian. * __le32 le32_replace_bits(__le32 old, u32 v, u32 field) is equivalent to ({__le32 tmp = old; le32p_replace_bits(&tmp, v, field); tmp;}) In other words, instead of modifying an object in memory, it takes the initial value and returns the modified one. * __le32 le32_encode_bits(u32 v, u32 field) is equivalent to le32_replace_bits(0, v, field). In other words, it returns a little-endian 32bit object with the bitfield specified by @field containing the value of @v and all bits outside that bitfield being zero. Such set of helpers is defined for each of little-, big- and host-endian types; e.g. u64_get_bits(val, field) will return the contents of the bitfield specified by @field in host-endian 64bit object @val, etc. Of course, for host-endian no conversion is involved. Fields to access are specified as GENMASK() values - an N-bit field starting at bit #M is encoded as GENMASK(M + N - 1, M). Note that bit numbers refer to endianness of the object we are working with - e.g. GENMASK(11, 0) in __be16 refers to the second byte and the lower 4 bits of the first byte. In __le16 it would refer to the first byte and the lower 4 bits of the second byte, etc. Field specification must be a constant; __builtin_constant_p() doesn't have to be true for it, but compiler must be able to evaluate it at build time. If it cannot or if the value does not encode any bitfield, the build will fail. If the value being stored in a bitfield is a constant that does not fit into that bitfield, a warning will be generated at compile time. Signed-off-by: Al Viro