From: Gao Xiang <gaoxiang25@huawei.com> To: Alexander Viro <viro@zeniv.linux.org.uk>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Andrew Morton <akpm@linux-foundation.org>, Stephen Rothwell <sfr@canb.auug.org.au>, Theodore Ts'o <tytso@mit.edu>, "Linus Torvalds" <torvalds@linux-foundation.org> Cc: <linux-fsdevel@vger.kernel.org>, <devel@driverdev.osuosl.org>, LKML <linux-kernel@vger.kernel.org>, <linux-erofs@lists.ozlabs.org>, Chao Yu <yuchao0@huawei.com>, Miao Xie <miaoxie@huawei.com>, Li Guifu <bluce.liguifu@huawei.com>, Fang Wei <fangwei1@huawei.com>, Gao Xiang <gaoxiang25@huawei.com> Subject: [PATCH v3 12/24] erofs: introduce tagged pointer Date: Mon, 22 Jul 2019 10:50:31 +0800 [thread overview] Message-ID: <20190722025043.166344-13-gaoxiang25@huawei.com> (raw) In-Reply-To: <20190722025043.166344-1-gaoxiang25@huawei.com> Currently kernel has scattered tagged pointer usages hacked by hand in plain code, without a unique and portable functionset to highlight the tagged pointer itself and wrap these hacked code in order to clean up all over meaningless magic masks. This patch introduces simple generic methods to fold tags into a pointer integer. Currently it supports the last n bits of the pointer for tags, which can be selected by users. In addition, it will also be used for the upcoming EROFS filesystem, which heavily uses tagged pointer pproach to reduce extra memory allocation. Link: https://en.wikipedia.org/wiki/Tagged_pointer Signed-off-by: Gao Xiang <gaoxiang25@huawei.com> --- fs/erofs/tagptr.h | 110 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 110 insertions(+) create mode 100644 fs/erofs/tagptr.h diff --git a/fs/erofs/tagptr.h b/fs/erofs/tagptr.h new file mode 100644 index 000000000000..121403cff2a3 --- /dev/null +++ b/fs/erofs/tagptr.h @@ -0,0 +1,110 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Tagged pointer implementation + * + * Copyright (C) 2018 Gao Xiang <gaoxiang25@huawei.com> + */ +#ifndef __EROFS_TAGPTR_H +#define __EROFS_TAGPTR_H + +#include <linux/types.h> +#include <linux/build_bug.h> + +/* + * the name of tagged pointer types are tagptr{1, 2, 3...}_t + * avoid directly using the internal structs __tagptr{1, 2, 3...} + */ +#define __MAKE_TAGPTR(n) \ +typedef struct __tagptr##n { \ + uintptr_t v; \ +} tagptr##n##_t; + +__MAKE_TAGPTR(1) +__MAKE_TAGPTR(2) +__MAKE_TAGPTR(3) +__MAKE_TAGPTR(4) + +#undef __MAKE_TAGPTR + +extern void __compiletime_error("bad tagptr tags") + __bad_tagptr_tags(void); + +extern void __compiletime_error("bad tagptr type") + __bad_tagptr_type(void); + +/* fix the broken usage of "#define tagptr2_t tagptr3_t" by users */ +#define __tagptr_mask_1(ptr, n) \ + __builtin_types_compatible_p(typeof(ptr), struct __tagptr##n) ? \ + (1UL << (n)) - 1 : + +#define __tagptr_mask(ptr) (\ + __tagptr_mask_1(ptr, 1) ( \ + __tagptr_mask_1(ptr, 2) ( \ + __tagptr_mask_1(ptr, 3) ( \ + __tagptr_mask_1(ptr, 4) ( \ + __bad_tagptr_type(), 0))))) + +/* generate a tagged pointer from a raw value */ +#define tagptr_init(type, val) \ + ((typeof(type)){ .v = (uintptr_t)(val) }) + +/* + * directly cast a tagged pointer to the native pointer type, which + * could be used for backward compatibility of existing code. + */ +#define tagptr_cast_ptr(tptr) ((void *)(tptr).v) + +/* encode tagged pointers */ +#define tagptr_fold(type, ptr, _tags) ({ \ + const typeof(_tags) tags = (_tags); \ + if (__builtin_constant_p(tags) && (tags & ~__tagptr_mask(type))) \ + __bad_tagptr_tags(); \ +tagptr_init(type, (uintptr_t)(ptr) | tags); }) + +/* decode tagged pointers */ +#define tagptr_unfold_ptr(tptr) \ + ((void *)((tptr).v & ~__tagptr_mask(tptr))) + +#define tagptr_unfold_tags(tptr) \ + ((tptr).v & __tagptr_mask(tptr)) + +/* operations for the tagger pointer */ +#define tagptr_eq(_tptr1, _tptr2) ({ \ + typeof(_tptr1) tptr1 = (_tptr1); \ + typeof(_tptr2) tptr2 = (_tptr2); \ + (void)(&tptr1 == &tptr2); \ +(tptr1).v == (tptr2).v; }) + +/* lock-free CAS operation */ +#define tagptr_cmpxchg(_ptptr, _o, _n) ({ \ + typeof(_ptptr) ptptr = (_ptptr); \ + typeof(_o) o = (_o); \ + typeof(_n) n = (_n); \ + (void)(&o == &n); \ + (void)(&o == ptptr); \ +tagptr_init(o, cmpxchg(&ptptr->v, o.v, n.v)); }) + +/* wrap WRITE_ONCE if atomic update is needed */ +#define tagptr_replace_tags(_ptptr, tags) ({ \ + typeof(_ptptr) ptptr = (_ptptr); \ + *ptptr = tagptr_fold(*ptptr, tagptr_unfold_ptr(*ptptr), tags); \ +*ptptr; }) + +#define tagptr_set_tags(_ptptr, _tags) ({ \ + typeof(_ptptr) ptptr = (_ptptr); \ + const typeof(_tags) tags = (_tags); \ + if (__builtin_constant_p(tags) && (tags & ~__tagptr_mask(*ptptr))) \ + __bad_tagptr_tags(); \ + ptptr->v |= tags; \ +*ptptr; }) + +#define tagptr_clear_tags(_ptptr, _tags) ({ \ + typeof(_ptptr) ptptr = (_ptptr); \ + const typeof(_tags) tags = (_tags); \ + if (__builtin_constant_p(tags) && (tags & ~__tagptr_mask(*ptptr))) \ + __bad_tagptr_tags(); \ + ptptr->v &= ~tags; \ +*ptptr; }) + +#endif + -- 2.17.1
WARNING: multiple messages have this Message-ID (diff)
From: gaoxiang25@huawei.com (Gao Xiang) Subject: [PATCH v3 12/24] erofs: introduce tagged pointer Date: Mon, 22 Jul 2019 10:50:31 +0800 [thread overview] Message-ID: <20190722025043.166344-13-gaoxiang25@huawei.com> (raw) In-Reply-To: <20190722025043.166344-1-gaoxiang25@huawei.com> Currently kernel has scattered tagged pointer usages hacked by hand in plain code, without a unique and portable functionset to highlight the tagged pointer itself and wrap these hacked code in order to clean up all over meaningless magic masks. This patch introduces simple generic methods to fold tags into a pointer integer. Currently it supports the last n bits of the pointer for tags, which can be selected by users. In addition, it will also be used for the upcoming EROFS filesystem, which heavily uses tagged pointer pproach to reduce extra memory allocation. Link: https://en.wikipedia.org/wiki/Tagged_pointer Signed-off-by: Gao Xiang <gaoxiang25 at huawei.com> --- fs/erofs/tagptr.h | 110 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 110 insertions(+) create mode 100644 fs/erofs/tagptr.h diff --git a/fs/erofs/tagptr.h b/fs/erofs/tagptr.h new file mode 100644 index 000000000000..121403cff2a3 --- /dev/null +++ b/fs/erofs/tagptr.h @@ -0,0 +1,110 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Tagged pointer implementation + * + * Copyright (C) 2018 Gao Xiang <gaoxiang25 at huawei.com> + */ +#ifndef __EROFS_TAGPTR_H +#define __EROFS_TAGPTR_H + +#include <linux/types.h> +#include <linux/build_bug.h> + +/* + * the name of tagged pointer types are tagptr{1, 2, 3...}_t + * avoid directly using the internal structs __tagptr{1, 2, 3...} + */ +#define __MAKE_TAGPTR(n) \ +typedef struct __tagptr##n { \ + uintptr_t v; \ +} tagptr##n##_t; + +__MAKE_TAGPTR(1) +__MAKE_TAGPTR(2) +__MAKE_TAGPTR(3) +__MAKE_TAGPTR(4) + +#undef __MAKE_TAGPTR + +extern void __compiletime_error("bad tagptr tags") + __bad_tagptr_tags(void); + +extern void __compiletime_error("bad tagptr type") + __bad_tagptr_type(void); + +/* fix the broken usage of "#define tagptr2_t tagptr3_t" by users */ +#define __tagptr_mask_1(ptr, n) \ + __builtin_types_compatible_p(typeof(ptr), struct __tagptr##n) ? \ + (1UL << (n)) - 1 : + +#define __tagptr_mask(ptr) (\ + __tagptr_mask_1(ptr, 1) ( \ + __tagptr_mask_1(ptr, 2) ( \ + __tagptr_mask_1(ptr, 3) ( \ + __tagptr_mask_1(ptr, 4) ( \ + __bad_tagptr_type(), 0))))) + +/* generate a tagged pointer from a raw value */ +#define tagptr_init(type, val) \ + ((typeof(type)){ .v = (uintptr_t)(val) }) + +/* + * directly cast a tagged pointer to the native pointer type, which + * could be used for backward compatibility of existing code. + */ +#define tagptr_cast_ptr(tptr) ((void *)(tptr).v) + +/* encode tagged pointers */ +#define tagptr_fold(type, ptr, _tags) ({ \ + const typeof(_tags) tags = (_tags); \ + if (__builtin_constant_p(tags) && (tags & ~__tagptr_mask(type))) \ + __bad_tagptr_tags(); \ +tagptr_init(type, (uintptr_t)(ptr) | tags); }) + +/* decode tagged pointers */ +#define tagptr_unfold_ptr(tptr) \ + ((void *)((tptr).v & ~__tagptr_mask(tptr))) + +#define tagptr_unfold_tags(tptr) \ + ((tptr).v & __tagptr_mask(tptr)) + +/* operations for the tagger pointer */ +#define tagptr_eq(_tptr1, _tptr2) ({ \ + typeof(_tptr1) tptr1 = (_tptr1); \ + typeof(_tptr2) tptr2 = (_tptr2); \ + (void)(&tptr1 == &tptr2); \ +(tptr1).v == (tptr2).v; }) + +/* lock-free CAS operation */ +#define tagptr_cmpxchg(_ptptr, _o, _n) ({ \ + typeof(_ptptr) ptptr = (_ptptr); \ + typeof(_o) o = (_o); \ + typeof(_n) n = (_n); \ + (void)(&o == &n); \ + (void)(&o == ptptr); \ +tagptr_init(o, cmpxchg(&ptptr->v, o.v, n.v)); }) + +/* wrap WRITE_ONCE if atomic update is needed */ +#define tagptr_replace_tags(_ptptr, tags) ({ \ + typeof(_ptptr) ptptr = (_ptptr); \ + *ptptr = tagptr_fold(*ptptr, tagptr_unfold_ptr(*ptptr), tags); \ +*ptptr; }) + +#define tagptr_set_tags(_ptptr, _tags) ({ \ + typeof(_ptptr) ptptr = (_ptptr); \ + const typeof(_tags) tags = (_tags); \ + if (__builtin_constant_p(tags) && (tags & ~__tagptr_mask(*ptptr))) \ + __bad_tagptr_tags(); \ + ptptr->v |= tags; \ +*ptptr; }) + +#define tagptr_clear_tags(_ptptr, _tags) ({ \ + typeof(_ptptr) ptptr = (_ptptr); \ + const typeof(_tags) tags = (_tags); \ + if (__builtin_constant_p(tags) && (tags & ~__tagptr_mask(*ptptr))) \ + __bad_tagptr_tags(); \ + ptptr->v &= ~tags; \ +*ptptr; }) + +#endif + -- 2.17.1
next prev parent reply other threads:[~2019-07-22 2:52 UTC|newest] Thread overview: 92+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-07-22 2:50 [PATCH v3 00/24] erofs: promote erofs from staging Gao Xiang 2019-07-22 2:50 ` Gao Xiang 2019-07-22 2:50 ` [PATCH v3 01/24] erofs: add on-disk layout Gao Xiang 2019-07-22 2:50 ` Gao Xiang 2019-07-22 2:50 ` Gao Xiang 2019-07-22 3:26 ` Stephen Rothwell 2019-07-22 3:26 ` Stephen Rothwell 2019-07-22 3:26 ` Stephen Rothwell 2019-07-22 3:29 ` Gao Xiang 2019-07-22 3:29 ` Gao Xiang 2019-07-22 5:05 ` Greg Kroah-Hartman 2019-07-22 5:05 ` Greg Kroah-Hartman 2019-07-22 5:24 ` Gao Xiang 2019-07-22 5:24 ` Gao Xiang 2019-07-22 2:50 ` [PATCH v3 02/24] erofs: add erofs in-memory stuffs Gao Xiang 2019-07-22 2:50 ` Gao Xiang 2019-07-22 2:50 ` [PATCH v3 03/24] erofs: add super block operations Gao Xiang 2019-07-22 2:50 ` Gao Xiang 2019-07-22 2:50 ` [PATCH v3 04/24] erofs: add raw address_space operations Gao Xiang 2019-07-22 2:50 ` Gao Xiang 2019-07-22 2:50 ` [PATCH v3 05/24] erofs: add inode operations Gao Xiang 2019-07-22 2:50 ` Gao Xiang 2019-07-22 2:50 ` [PATCH v3 06/24] erofs: support special inode Gao Xiang 2019-07-22 2:50 ` Gao Xiang 2019-07-22 2:50 ` [PATCH v3 07/24] erofs: add directory operations Gao Xiang 2019-07-22 2:50 ` Gao Xiang 2019-07-22 2:50 ` [PATCH v3 08/24] erofs: add namei functions Gao Xiang 2019-07-22 2:50 ` Gao Xiang 2019-07-22 2:50 ` [PATCH v3 09/24] erofs: support tracepoint Gao Xiang 2019-07-22 2:50 ` Gao Xiang 2019-07-22 2:50 ` [PATCH v3 10/24] erofs: update Kconfig and Makefile Gao Xiang 2019-07-22 2:50 ` Gao Xiang 2019-07-22 2:50 ` [PATCH v3 11/24] erofs: introduce xattr & posixacl support Gao Xiang 2019-07-22 2:50 ` Gao Xiang 2019-07-22 2:50 ` Gao Xiang [this message] 2019-07-22 2:50 ` [PATCH v3 12/24] erofs: introduce tagged pointer Gao Xiang 2019-07-22 4:39 ` Amir Goldstein 2019-07-22 4:39 ` Amir Goldstein 2019-07-22 5:01 ` Gao Xiang 2019-07-22 5:01 ` Gao Xiang 2019-07-22 6:16 ` Amir Goldstein 2019-07-22 6:16 ` Amir Goldstein 2019-07-22 6:31 ` Gao Xiang 2019-07-22 6:31 ` Gao Xiang 2019-07-22 14:40 ` Steven Rostedt 2019-07-22 14:40 ` Steven Rostedt 2019-07-22 15:33 ` Gao Xiang 2019-07-22 15:33 ` Gao Xiang 2019-07-22 16:35 ` Steven Rostedt 2019-07-22 16:35 ` Steven Rostedt 2019-07-22 16:52 ` Gao Xiang 2019-07-22 16:52 ` Gao Xiang 2019-07-22 2:50 ` [PATCH v3 13/24] erofs: add compression indexes support Gao Xiang 2019-07-22 2:50 ` Gao Xiang 2019-07-22 2:50 ` [PATCH v3 14/24] erofs: introduce superblock registration Gao Xiang 2019-07-22 2:50 ` Gao Xiang 2019-07-22 2:50 ` [PATCH v3 15/24] erofs: introduce erofs shrinker Gao Xiang 2019-07-22 2:50 ` Gao Xiang 2019-07-22 2:50 ` [PATCH v3 16/24] erofs: introduce workstation for decompression Gao Xiang 2019-07-22 2:50 ` Gao Xiang 2019-07-22 2:50 ` [PATCH v3 17/24] erofs: introduce per-CPU buffers implementation Gao Xiang 2019-07-22 2:50 ` Gao Xiang 2019-07-22 2:50 ` [PATCH v3 18/24] erofs: introduce pagevec for decompression subsystem Gao Xiang 2019-07-22 2:50 ` Gao Xiang 2019-07-22 2:50 ` [PATCH v3 19/24] erofs: add erofs_allocpage() Gao Xiang 2019-07-22 2:50 ` Gao Xiang 2019-07-22 2:50 ` [PATCH v3 20/24] erofs: introduce generic decompression backend Gao Xiang 2019-07-22 2:50 ` Gao Xiang 2019-07-22 2:50 ` [PATCH v3 21/24] erofs: introduce LZ4 decompression inplace Gao Xiang 2019-07-22 2:50 ` Gao Xiang 2019-07-22 2:50 ` [PATCH v3 22/24] erofs: introduce the decompression frontend Gao Xiang 2019-07-22 2:50 ` Gao Xiang 2019-07-22 2:50 ` [PATCH v3 23/24] erofs: introduce cached decompression Gao Xiang 2019-07-22 2:50 ` Gao Xiang 2019-07-22 10:18 ` David Sterba 2019-07-22 10:18 ` David Sterba 2019-07-22 10:58 ` Gao Xiang 2019-07-22 10:58 ` Gao Xiang 2019-07-22 13:25 ` Theodore Y. Ts'o 2019-07-22 13:25 ` Theodore Y. Ts'o 2019-07-22 14:16 ` Gao Xiang 2019-07-22 14:16 ` Gao Xiang 2019-07-22 15:12 ` Theodore Y. Ts'o 2019-07-22 15:12 ` Theodore Y. Ts'o 2019-07-22 16:27 ` Gao Xiang 2019-07-22 16:27 ` Gao Xiang 2019-07-23 12:31 ` David Sterba 2019-07-23 12:31 ` David Sterba 2019-07-23 13:30 ` Gao Xiang 2019-07-23 13:30 ` Gao Xiang 2019-07-22 2:50 ` [PATCH v3 24/24] erofs: add document Gao Xiang 2019-07-22 2:50 ` Gao Xiang
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