kernel_samsung_a53x/include/uapi/linux/stddef.h

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2024-06-15 16:02:09 -03:00
/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
#ifndef _UAPI_LINUX_STDDEF_H
#define _UAPI_LINUX_STDDEF_H
#include <linux/compiler_types.h>
#ifndef __always_inline
#define __always_inline inline
#endif
/**
* __struct_group() - Create a mirrored named and anonyomous struct
*
* @TAG: The tag name for the named sub-struct (usually empty)
* @NAME: The identifier name of the mirrored sub-struct
* @ATTRS: Any struct attributes (usually empty)
* @MEMBERS: The member declarations for the mirrored structs
*
* Used to create an anonymous union of two structs with identical layout
* and size: one anonymous and one named. The former's members can be used
* normally without sub-struct naming, and the latter can be used to
* reason about the start, end, and size of the group of struct members.
* The named struct can also be explicitly tagged for layer reuse, as well
* as both having struct attributes appended.
*/
#define __struct_group(TAG, NAME, ATTRS, MEMBERS...) \
union { \
struct { MEMBERS } ATTRS; \
struct TAG { MEMBERS } ATTRS NAME; \
}
stddef: Introduce DECLARE_FLEX_ARRAY() helper commit 3080ea5553cc909b000d1f1d964a9041962f2c5b upstream. There are many places where kernel code wants to have several different typed trailing flexible arrays. This would normally be done with multiple flexible arrays in a union, but since GCC and Clang don't (on the surface) allow this, there have been many open-coded workarounds, usually involving neighboring 0-element arrays at the end of a structure. For example, instead of something like this: struct thing { ... union { struct type1 foo[]; struct type2 bar[]; }; }; code works around the compiler with: struct thing { ... struct type1 foo[0]; struct type2 bar[]; }; Another case is when a flexible array is wanted as the single member within a struct (which itself is usually in a union). For example, this would be worked around as: union many { ... struct { struct type3 baz[0]; }; }; These kinds of work-arounds cause problems with size checks against such zero-element arrays (for example when building with -Warray-bounds and -Wzero-length-bounds, and with the coming FORTIFY_SOURCE improvements), so they must all be converted to "real" flexible arrays, avoiding warnings like this: fs/hpfs/anode.c: In function 'hpfs_add_sector_to_btree': fs/hpfs/anode.c:209:27: warning: array subscript 0 is outside the bounds of an interior zero-length array 'struct bplus_internal_node[0]' [-Wzero-length-bounds] 209 | anode->btree.u.internal[0].down = cpu_to_le32(a); | ~~~~~~~~~~~~~~~~~~~~~~~^~~ In file included from fs/hpfs/hpfs_fn.h:26, from fs/hpfs/anode.c:10: fs/hpfs/hpfs.h:412:32: note: while referencing 'internal' 412 | struct bplus_internal_node internal[0]; /* (internal) 2-word entries giving | ^~~~~~~~ drivers/net/can/usb/etas_es58x/es58x_fd.c: In function 'es58x_fd_tx_can_msg': drivers/net/can/usb/etas_es58x/es58x_fd.c:360:35: warning: array subscript 65535 is outside the bounds of an interior zero-length array 'u8[0]' {aka 'unsigned char[]'} [-Wzero-length-bounds] 360 | tx_can_msg = (typeof(tx_can_msg))&es58x_fd_urb_cmd->raw_msg[msg_len]; | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ In file included from drivers/net/can/usb/etas_es58x/es58x_core.h:22, from drivers/net/can/usb/etas_es58x/es58x_fd.c:17: drivers/net/can/usb/etas_es58x/es58x_fd.h:231:6: note: while referencing 'raw_msg' 231 | u8 raw_msg[0]; | ^~~~~~~ However, it _is_ entirely possible to have one or more flexible arrays in a struct or union: it just has to be in another struct. And since it cannot be alone in a struct, such a struct must have at least 1 other named member -- but that member can be zero sized. Wrap all this nonsense into the new DECLARE_FLEX_ARRAY() in support of having flexible arrays in unions (or alone in a struct). As with struct_group(), since this is needed in UAPI headers as well, implement the core there, with a non-UAPI wrapper. Additionally update kernel-doc to understand its existence. https://github.com/KSPP/linux/issues/137 Cc: Arnd Bergmann <arnd@arndb.de> Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org> Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: Vasiliy Kovalev <kovalev@altlinux.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-01-26 22:31:42 +03:00
#ifdef __cplusplus
/* sizeof(struct{}) is 1 in C++, not 0, can't use C version of the macro. */
#define __DECLARE_FLEX_ARRAY(T, member) \
T member[0]
#else
stddef: Introduce DECLARE_FLEX_ARRAY() helper commit 3080ea5553cc909b000d1f1d964a9041962f2c5b upstream. There are many places where kernel code wants to have several different typed trailing flexible arrays. This would normally be done with multiple flexible arrays in a union, but since GCC and Clang don't (on the surface) allow this, there have been many open-coded workarounds, usually involving neighboring 0-element arrays at the end of a structure. For example, instead of something like this: struct thing { ... union { struct type1 foo[]; struct type2 bar[]; }; }; code works around the compiler with: struct thing { ... struct type1 foo[0]; struct type2 bar[]; }; Another case is when a flexible array is wanted as the single member within a struct (which itself is usually in a union). For example, this would be worked around as: union many { ... struct { struct type3 baz[0]; }; }; These kinds of work-arounds cause problems with size checks against such zero-element arrays (for example when building with -Warray-bounds and -Wzero-length-bounds, and with the coming FORTIFY_SOURCE improvements), so they must all be converted to "real" flexible arrays, avoiding warnings like this: fs/hpfs/anode.c: In function 'hpfs_add_sector_to_btree': fs/hpfs/anode.c:209:27: warning: array subscript 0 is outside the bounds of an interior zero-length array 'struct bplus_internal_node[0]' [-Wzero-length-bounds] 209 | anode->btree.u.internal[0].down = cpu_to_le32(a); | ~~~~~~~~~~~~~~~~~~~~~~~^~~ In file included from fs/hpfs/hpfs_fn.h:26, from fs/hpfs/anode.c:10: fs/hpfs/hpfs.h:412:32: note: while referencing 'internal' 412 | struct bplus_internal_node internal[0]; /* (internal) 2-word entries giving | ^~~~~~~~ drivers/net/can/usb/etas_es58x/es58x_fd.c: In function 'es58x_fd_tx_can_msg': drivers/net/can/usb/etas_es58x/es58x_fd.c:360:35: warning: array subscript 65535 is outside the bounds of an interior zero-length array 'u8[0]' {aka 'unsigned char[]'} [-Wzero-length-bounds] 360 | tx_can_msg = (typeof(tx_can_msg))&es58x_fd_urb_cmd->raw_msg[msg_len]; | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ In file included from drivers/net/can/usb/etas_es58x/es58x_core.h:22, from drivers/net/can/usb/etas_es58x/es58x_fd.c:17: drivers/net/can/usb/etas_es58x/es58x_fd.h:231:6: note: while referencing 'raw_msg' 231 | u8 raw_msg[0]; | ^~~~~~~ However, it _is_ entirely possible to have one or more flexible arrays in a struct or union: it just has to be in another struct. And since it cannot be alone in a struct, such a struct must have at least 1 other named member -- but that member can be zero sized. Wrap all this nonsense into the new DECLARE_FLEX_ARRAY() in support of having flexible arrays in unions (or alone in a struct). As with struct_group(), since this is needed in UAPI headers as well, implement the core there, with a non-UAPI wrapper. Additionally update kernel-doc to understand its existence. https://github.com/KSPP/linux/issues/137 Cc: Arnd Bergmann <arnd@arndb.de> Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org> Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: Vasiliy Kovalev <kovalev@altlinux.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-01-26 22:31:42 +03:00
/**
* __DECLARE_FLEX_ARRAY() - Declare a flexible array usable in a union
*
* @TYPE: The type of each flexible array element
* @NAME: The name of the flexible array member
*
* In order to have a flexible array member in a union or alone in a
* struct, it needs to be wrapped in an anonymous struct with at least 1
* named member, but that member can be empty.
*/
#define __DECLARE_FLEX_ARRAY(TYPE, NAME) \
struct { \
struct { } __empty_ ## NAME; \
TYPE NAME[]; \
}
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#endif
#endif