mm: add ksys_fadvise64_64() helper; remove in-kernel call to sys_fadvise64_64()

Using the ksys_fadvise64_64() helper allows us to avoid the in-kernel
calls to the sys_fadvise64_64() syscall. The ksys_ prefix denotes that
this function is meant as a drop-in replacement for the syscall. In
particular, it uses the same calling convention as ksys_fadvise64_64().

Some compat stubs called sys_fadvise64(), which then just passed through
the arguments to sys_fadvise64_64(). Get rid of this indirection, and call
ksys_fadvise64_64() directly.

This patch is part of a series which removes in-kernel calls to syscalls.
On this basis, the syscall entry path can be streamlined. For details, see
http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>

diff --git a/arch/arm/kernel/sys_arm.c b/arch/arm/kernel/sys_arm.c
index 3151f56..bdf7514 100644 (file)
--- a/arch/arm/kernel/sys_arm.c
+++ b/arch/arm/kernel/sys_arm.c
@@ -35,5 +35,5 @@
 asmlinkage long sys_arm_fadvise64_64(int fd, int advice,
                                     loff_t offset, loff_t len)
 {
-       return sys_fadvise64_64(fd, offset, len, advice);
+       return ksys_fadvise64_64(fd, offset, len, advice);
 }

diff --git a/arch/mips/kernel/linux32.c b/arch/mips/kernel/linux32.c
index 0779d47..1c5785e 100644 (file)
--- a/arch/mips/kernel/linux32.c
+++ b/arch/mips/kernel/linux32.c
@@ -149,7 +149,7 @@ asmlinkage long sys32_fadvise64_64(int fd, int __pad,
        unsigned long a4, unsigned long a5,
        int flags)
 {
-       return sys_fadvise64_64(fd,
+       return ksys_fadvise64_64(fd,
                        merge_64(a2, a3), merge_64(a4, a5),
                        flags);
 }

diff --git a/arch/parisc/kernel/sys_parisc.c b/arch/parisc/kernel/sys_parisc.c
index 588fab3..f36ab1f 100644 (file)
--- a/arch/parisc/kernel/sys_parisc.c
+++ b/arch/parisc/kernel/sys_parisc.c
@@ -352,7 +352,7 @@ asmlinkage long parisc_fadvise64_64(int fd,
                        unsigned int high_off, unsigned int low_off,
                        unsigned int high_len, unsigned int low_len, int advice)
 {
-       return sys_fadvise64_64(fd, (loff_t)high_off << 32 | low_off,
+       return ksys_fadvise64_64(fd, (loff_t)high_off << 32 | low_off,
                        (loff_t)high_len << 32 | low_len, advice);
 }
 

diff --git a/arch/powerpc/kernel/sys_ppc32.c b/arch/powerpc/kernel/sys_ppc32.c
index 68f11e1..0b95fa1 100644 (file)
--- a/arch/powerpc/kernel/sys_ppc32.c
+++ b/arch/powerpc/kernel/sys_ppc32.c
@@ -113,8 +113,8 @@ asmlinkage int compat_sys_ftruncate64(unsigned int fd, u32 reg4, unsigned long h
 long ppc32_fadvise64(int fd, u32 unused, u32 offset_high, u32 offset_low,
                     size_t len, int advice)
 {
-       return sys_fadvise64(fd, (u64)offset_high << 32 | offset_low, len,
-                            advice);
+       return ksys_fadvise64_64(fd, (u64)offset_high << 32 | offset_low, len,
+                                advice);
 }
 
 asmlinkage long compat_sys_sync_file_range2(int fd, unsigned int flags,

diff --git a/arch/powerpc/kernel/syscalls.c b/arch/powerpc/kernel/syscalls.c
index a877bf8..ecb981e 100644 (file)
--- a/arch/powerpc/kernel/syscalls.c
+++ b/arch/powerpc/kernel/syscalls.c
@@ -119,8 +119,8 @@ long ppc64_personality(unsigned long personality)
 long ppc_fadvise64_64(int fd, int advice, u32 offset_high, u32 offset_low,
                      u32 len_high, u32 len_low)
 {
-       return sys_fadvise64(fd, (u64)offset_high << 32 | offset_low,
-                            (u64)len_high << 32 | len_low, advice);
+       return ksys_fadvise64_64(fd, (u64)offset_high << 32 | offset_low,
+                                (u64)len_high << 32 | len_low, advice);
 }
 
 long sys_switch_endian(void)

diff --git a/arch/s390/kernel/compat_linux.c b/arch/s390/kernel/compat_linux.c
index 039858f..9bb897e 100644 (file)
--- a/arch/s390/kernel/compat_linux.c
+++ b/arch/s390/kernel/compat_linux.c
@@ -483,7 +483,8 @@ COMPAT_SYSCALL_DEFINE5(s390_fadvise64, int, fd, u32, high, u32, low, compat_size
                advise = POSIX_FADV_DONTNEED;
        else if (advise == 5)
                advise = POSIX_FADV_NOREUSE;
-       return sys_fadvise64(fd, (unsigned long)high << 32 | low, len, advise);
+       return ksys_fadvise64_64(fd, (unsigned long)high << 32 | low, len,
+                                advise);
 }
 
 struct fadvise64_64_args {
@@ -503,7 +504,7 @@ COMPAT_SYSCALL_DEFINE1(s390_fadvise64_64, struct fadvise64_64_args __user *, arg
                a.advice = POSIX_FADV_DONTNEED;
        else if (a.advice == 5)
                a.advice = POSIX_FADV_NOREUSE;
-       return sys_fadvise64_64(a.fd, a.offset, a.len, a.advice);
+       return ksys_fadvise64_64(a.fd, a.offset, a.len, a.advice);
 }
 
 COMPAT_SYSCALL_DEFINE6(s390_sync_file_range, int, fd, u32, offhigh, u32, offlow,

diff --git a/arch/sh/kernel/sys_sh32.c b/arch/sh/kernel/sys_sh32.c
index c37ee3d..9dca568 100644 (file)
--- a/arch/sh/kernel/sys_sh32.c
+++ b/arch/sh/kernel/sys_sh32.c
@@ -52,10 +52,10 @@ asmlinkage int sys_fadvise64_64_wrapper(int fd, u32 offset0, u32 offset1,
                                u32 len0, u32 len1, int advice)
 {
 #ifdef  __LITTLE_ENDIAN__
-       return sys_fadvise64_64(fd, (u64)offset1 << 32 | offset0,
-                               (u64)len1 << 32 | len0, advice);
+       return ksys_fadvise64_64(fd, (u64)offset1 << 32 | offset0,
+                                (u64)len1 << 32 | len0, advice);
 #else
-       return sys_fadvise64_64(fd, (u64)offset0 << 32 | offset1,
-                               (u64)len0 << 32 | len1, advice);
+       return ksys_fadvise64_64(fd, (u64)offset0 << 32 | offset1,
+                                (u64)len0 << 32 | len1, advice);
 #endif
 }

diff --git a/arch/sparc/kernel/sys_sparc32.c b/arch/sparc/kernel/sys_sparc32.c
index 4ba62d6..4da66ae 100644 (file)
--- a/arch/sparc/kernel/sys_sparc32.c
+++ b/arch/sparc/kernel/sys_sparc32.c
@@ -225,7 +225,7 @@ long compat_sys_fadvise64(int fd,
                          unsigned long offlo,
                          compat_size_t len, int advice)
 {
-       return sys_fadvise64_64(fd, (offhi << 32) | offlo, len, advice);
+       return ksys_fadvise64_64(fd, (offhi << 32) | offlo, len, advice);
 }
 
 long compat_sys_fadvise64_64(int fd,
@@ -233,10 +233,10 @@ long compat_sys_fadvise64_64(int fd,
                             unsigned long lenhi, unsigned long lenlo,
                             int advice)
 {
-       return sys_fadvise64_64(fd,
-                               (offhi << 32) | offlo,
-                               (lenhi << 32) | lenlo,
-                               advice);
+       return ksys_fadvise64_64(fd,
+                                (offhi << 32) | offlo,
+                                (lenhi << 32) | lenlo,
+                                advice);
 }
 
 long sys32_sync_file_range(unsigned int fd, unsigned long off_high, unsigned long off_low, unsigned long nb_high, unsigned long nb_low, unsigned int flags)

diff --git a/arch/x86/ia32/sys_ia32.c b/arch/x86/ia32/sys_ia32.c
index df2acb1..401bd8e 100644 (file)
--- a/arch/x86/ia32/sys_ia32.c
+++ b/arch/x86/ia32/sys_ia32.c
@@ -194,10 +194,10 @@ COMPAT_SYSCALL_DEFINE6(x86_fadvise64_64, int, fd, __u32, offset_low,
                       __u32, offset_high, __u32, len_low, __u32, len_high,
                       int, advice)
 {
-       return sys_fadvise64_64(fd,
-                              (((u64)offset_high)<<32) | offset_low,
-                              (((u64)len_high)<<32) | len_low,
-                               advice);
+       return ksys_fadvise64_64(fd,
+                                (((u64)offset_high)<<32) | offset_low,
+                                (((u64)len_high)<<32) | len_low,
+                                advice);
 }
 
 COMPAT_SYSCALL_DEFINE4(x86_readahead, int, fd, unsigned int, off_lo,
@@ -218,8 +218,8 @@ COMPAT_SYSCALL_DEFINE6(x86_sync_file_range, int, fd, unsigned int, off_low,
 COMPAT_SYSCALL_DEFINE5(x86_fadvise64, int, fd, unsigned int, offset_lo,
                       unsigned int, offset_hi, size_t, len, int, advice)
 {
-       return sys_fadvise64_64(fd, ((u64)offset_hi << 32) | offset_lo,
-                               len, advice);
+       return ksys_fadvise64_64(fd, ((u64)offset_hi << 32) | offset_lo,
+                                len, advice);
 }
 
 COMPAT_SYSCALL_DEFINE6(x86_fallocate, int, fd, int, mode,

diff --git a/arch/xtensa/kernel/syscall.c b/arch/xtensa/kernel/syscall.c
index 74afbf0..8201748 100644 (file)
--- a/arch/xtensa/kernel/syscall.c
+++ b/arch/xtensa/kernel/syscall.c
@@ -55,7 +55,7 @@ asmlinkage long xtensa_shmat(int shmid, char __user *shmaddr, int shmflg)
 asmlinkage long xtensa_fadvise64_64(int fd, int advice,
                unsigned long long offset, unsigned long long len)
 {
-       return sys_fadvise64_64(fd, offset, len, advice);
+       return ksys_fadvise64_64(fd, offset, len, advice);
 }
 
 #ifdef CONFIG_MMU

diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 613b812..466d408 100644 (file)
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -970,6 +970,15 @@ ssize_t ksys_pread64(unsigned int fd, char __user *buf, size_t count,
 ssize_t ksys_pwrite64(unsigned int fd, const char __user *buf,
                      size_t count, loff_t pos);
 int ksys_fallocate(int fd, int mode, loff_t offset, loff_t len);
+#ifdef CONFIG_ADVISE_SYSCALLS
+int ksys_fadvise64_64(int fd, loff_t offset, loff_t len, int advice);
+#else
+static inline int ksys_fadvise64_64(int fd, loff_t offset, loff_t len,
+                                   int advice)
+{
+       return -EINVAL;
+}
+#endif
 
 /*
  * The following kernel syscall equivalents are just wrappers to fs-internal

diff --git a/mm/fadvise.c b/mm/fadvise.c
index 767887f..afa4149 100644 (file)
--- a/mm/fadvise.c
+++ b/mm/fadvise.c
@@ -26,7 +26,8 @@
  * POSIX_FADV_WILLNEED could set PG_Referenced, and POSIX_FADV_NOREUSE could
  * deactivate the pages and clear PG_Referenced.
  */
-SYSCALL_DEFINE4(fadvise64_64, int, fd, loff_t, offset, loff_t, len, int, advice)
+
+int ksys_fadvise64_64(int fd, loff_t offset, loff_t len, int advice)
 {
        struct fd f = fdget(fd);
        struct inode *inode;
@@ -185,11 +186,16 @@ out:
        return ret;
 }
 
+SYSCALL_DEFINE4(fadvise64_64, int, fd, loff_t, offset, loff_t, len, int, advice)
+{
+       return ksys_fadvise64_64(fd, offset, len, advice);
+}
+
 #ifdef __ARCH_WANT_SYS_FADVISE64
 
 SYSCALL_DEFINE4(fadvise64, int, fd, loff_t, offset, size_t, len, int, advice)
 {
-       return sys_fadvise64_64(fd, offset, len, advice);
+       return ksys_fadvise64_64(fd, offset, len, advice);
 }
 
 #endif