[RFC PATCH 2/4] Introduce fbind syscall
From: Shivank Garg <hidden>
Date: 2024-11-05 16:55:57
Also in:
kvm, linux-arch, linux-fsdevel, linux-mm, lkml
Subsystem:
abi/api, filesystems (vfs and infrastructure), generic include/asm header files, memory management, memory management - memory policy and migration, the rest, x86 architecture (32-bit and 64-bit), x86 entry code · Maintainers:
Alexander Viro, Christian Brauner, Arnd Bergmann, Andrew Morton, David Hildenbrand, Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen, Andy Lutomirski
The new fbind syscall sets the NUMA memory policy for file-backed memory
and has following signature:
long fbind(unsigned int fd, unsigned long mode,
const unsigned long nodemask[(.maxnode + ULONG_WIDTH - 1)
/ ULONG_WIDTH],
unsigned long maxnode, unsigned int flags);
fbind behaves similar to mbind except that it takes file descriptor as
input instead of address ranges.
TODO:
1. Support fbind syscall on all architectures.
2. Expand commit msg and add documentation.
3. clean-up the code.
[Shivansh: add create_mpol_from_args()]
Signed-off-by: Shivansh Dhiman <redacted>
Signed-off-by: Shivank Garg <redacted>
---
arch/x86/entry/syscalls/syscall_32.tbl | 1 +
arch/x86/entry/syscalls/syscall_64.tbl | 1 +
include/linux/fs.h | 3 ++
include/linux/mempolicy.h | 3 ++
include/linux/syscalls.h | 3 ++
include/uapi/asm-generic/unistd.h | 5 ++-
kernel/sys_ni.c | 1 +
mm/Makefile | 2 +-
mm/fbind.c | 49 +++++++++++++++++++++++
mm/mempolicy.c | 55 ++++++++++++++++++++++++++
10 files changed, 121 insertions(+), 2 deletions(-)
create mode 100644 mm/fbind.c
diff --git a/arch/x86/entry/syscalls/syscall_32.tbl b/arch/x86/entry/syscalls/syscall_32.tbl
index 534c74b14fab..0660ce6d08d8 100644
--- a/arch/x86/entry/syscalls/syscall_32.tbl
+++ b/arch/x86/entry/syscalls/syscall_32.tbl@@ -468,3 +468,4 @@ 460 i386 lsm_set_self_attr sys_lsm_set_self_attr 461 i386 lsm_list_modules sys_lsm_list_modules 462 i386 mseal sys_mseal +463 i386 fbind sys_fbind
diff --git a/arch/x86/entry/syscalls/syscall_64.tbl b/arch/x86/entry/syscalls/syscall_64.tbl
index 7093ee21c0d1..9794347cc2e6 100644
--- a/arch/x86/entry/syscalls/syscall_64.tbl
+++ b/arch/x86/entry/syscalls/syscall_64.tbl@@ -386,6 +386,7 @@ 460 common lsm_set_self_attr sys_lsm_set_self_attr 461 common lsm_list_modules sys_lsm_list_modules 462 common mseal sys_mseal +463 common fbind sys_fbind # # Due to a historical design error, certain syscalls are numbered differently
diff --git a/include/linux/fs.h b/include/linux/fs.h
index fd34b5755c0b..42042b62bdcd 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h@@ -2058,6 +2058,9 @@ struct file_operations { struct file *file_out, loff_t pos_out, loff_t len, unsigned int remap_flags); int (*fadvise)(struct file *, loff_t, loff_t, int); +#ifdef CONFIG_NUMA + int (*set_policy)(struct file *, struct mempolicy *); +#endif int (*uring_cmd)(struct io_uring_cmd *ioucmd, unsigned int issue_flags); int (*uring_cmd_iopoll)(struct io_uring_cmd *, struct io_comp_batch *, unsigned int poll_flags);
diff --git a/include/linux/mempolicy.h b/include/linux/mempolicy.h
index 1add16f21612..b9023f6246a7 100644
--- a/include/linux/mempolicy.h
+++ b/include/linux/mempolicy.h@@ -299,4 +299,7 @@ static inline bool mpol_is_preferred_many(struct mempolicy *pol) } #endif /* CONFIG_NUMA */ +struct mempolicy *create_mpol_from_args(unsigned char mode, + const unsigned long __user *nmask, + unsigned short maxnode); #endif
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 4bcf6754738d..2dc686921b9f 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h@@ -502,6 +502,9 @@ asmlinkage long sys_readlinkat(int dfd, const char __user *path, char __user *bu asmlinkage long sys_newfstatat(int dfd, const char __user *filename, struct stat __user *statbuf, int flag); asmlinkage long sys_newfstat(unsigned int fd, struct stat __user *statbuf); +asmlinkage long sys_fbind(unsigned int fd, unsigned long mode, + const unsigned long __user *nmask, + unsigned long maxnode, unsigned int flags); #if defined(__ARCH_WANT_STAT64) || defined(__ARCH_WANT_COMPAT_STAT64) asmlinkage long sys_fstat64(unsigned long fd, struct stat64 __user *statbuf); asmlinkage long sys_fstatat64(int dfd, const char __user *filename,
diff --git a/include/uapi/asm-generic/unistd.h b/include/uapi/asm-generic/unistd.h
index 5bf6148cac2b..550730f36dae 100644
--- a/include/uapi/asm-generic/unistd.h
+++ b/include/uapi/asm-generic/unistd.h@@ -841,8 +841,11 @@ __SYSCALL(__NR_lsm_list_modules, sys_lsm_list_modules) #define __NR_mseal 462 __SYSCALL(__NR_mseal, sys_mseal) +#define __NR_fbind 463 +__SYSCALL(__NR_fbind, sys_fbind) + #undef __NR_syscalls -#define __NR_syscalls 463 +#define __NR_syscalls 464 /* * 32 bit systems traditionally used different
diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c
index c00a86931f8c..f57350e581f6 100644
--- a/kernel/sys_ni.c
+++ b/kernel/sys_ni.c@@ -195,6 +195,7 @@ COND_SYSCALL(move_pages); COND_SYSCALL(set_mempolicy_home_node); COND_SYSCALL(cachestat); COND_SYSCALL(mseal); +COND_SYSCALL(fbind); COND_SYSCALL(perf_event_open); COND_SYSCALL(accept4);
diff --git a/mm/Makefile b/mm/Makefile
index d2915f8c9dc0..ba339ddc0be2 100644
--- a/mm/Makefile
+++ b/mm/Makefile@@ -79,7 +79,7 @@ obj-$(CONFIG_ZSWAP) += zswap.o obj-$(CONFIG_HAS_DMA) += dmapool.o obj-$(CONFIG_HUGETLBFS) += hugetlb.o obj-$(CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP) += hugetlb_vmemmap.o -obj-$(CONFIG_NUMA) += mempolicy.o +obj-$(CONFIG_NUMA) += mempolicy.o fbind.o obj-$(CONFIG_SPARSEMEM) += sparse.o obj-$(CONFIG_SPARSEMEM_VMEMMAP) += sparse-vmemmap.o obj-$(CONFIG_MMU_NOTIFIER) += mmu_notifier.o
diff --git a/mm/fbind.c b/mm/fbind.c
new file mode 100644
index 000000000000..85ec7d13345c
--- /dev/null
+++ b/mm/fbind.c@@ -0,0 +1,49 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Implement fbind() syscall. + * + * Copyright (c) 2024 AMD + * + * Author: Shivank Garg <shivankg@amd.com> + */ + +#include <linux/file.h> +#include <linux/fs.h> +#include <linux/mempolicy.h> +#include <linux/syscalls.h> + +static long do_fbind(unsigned int fd, unsigned long mode, + const unsigned long __user *nmask, + unsigned long maxnode, unsigned int flags) +{ + struct mempolicy *mpol; + struct fd f; + int ret; + + f = fdget(fd); + if (!f.file) + return -EBADF; + + mpol = create_mpol_from_args(mode, nmask, maxnode); + if (IS_ERR_OR_NULL(mpol)) { + ret = PTR_ERR(mpol); + goto out_putf; + } + + if (f.file->f_op->set_policy) + ret = f.file->f_op->set_policy(f.file, mpol); + else + ret = -EOPNOTSUPP; + + mpol_put(mpol); +out_putf: + fdput(f); + return ret; +} + +SYSCALL_DEFINE5(fbind, unsigned int, fd, unsigned long, mode, + const unsigned long __user *, nmask, + unsigned long, maxnode, unsigned int, flags) +{ + return do_fbind(fd, mode, nmask, maxnode, flags); +}
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index b858e22b259d..3a697080ecad 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c@@ -3557,3 +3557,58 @@ static int __init mempolicy_sysfs_init(void) late_initcall(mempolicy_sysfs_init); #endif /* CONFIG_SYSFS */ + +/** + * create_mpol_from_args - create a mempolicy structure from args + * @mode: NUMA memory policy mode + * @nmask: bitmask of NUMA nodes + * @maxnode: number of bits in the nodes bitmask + * + * Create a mempolicy from given nodemask and memory policy such as + * default, preferred, interleave or bind. + * + * Return: error encoded in a pointer or memory policy on success. + */ +struct mempolicy *create_mpol_from_args(unsigned char mode, + const unsigned long __user *nmask, + unsigned short maxnode) +{ + struct mm_struct *mm = current->mm; + unsigned short mode_flags; + struct mempolicy *mpol; + nodemask_t nodes; + int lmode = mode; + int err = -ENOMEM; + + err = sanitize_mpol_flags(&lmode, &mode_flags); + if (err) + return ERR_PTR(err); + + err = get_nodes(&nodes, nmask, maxnode); + if (err) + return ERR_PTR(err); + + mpol = mpol_new(mode, mode_flags, &nodes); + if (IS_ERR_OR_NULL(mpol)) + return mpol; + + NODEMASK_SCRATCH(scratch); + if (!scratch) { + err = -ENOMEM; + goto err_out; + } + + mmap_write_lock(mm); + err = mpol_set_nodemask(mpol, &nodes, scratch); + mmap_write_unlock(mm); + NODEMASK_SCRATCH_FREE(scratch); + + if (err) + goto err_out; + + return mpol; + +err_out: + mpol_put(mpol); + return ERR_PTR(err); +}
--
2.34.1