[PATCH 10/45] fs: add ksys_p{read,write}64() helpers; remove in-kernel calls to syscalls

From: Dominik Brodowski
Date: Thu Mar 22 2018 - 05:07:53 EST

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Using the ksys_p{read,write}64() wrappers allows us to get rid of
in-kernel calls to the sys_pread64() and sys_pwrite64() syscalls.
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 sys_p{read,write}64().

This patch is part of a series which tries to remove in-kernel calls to
syscalls. On this basis, the syscall entry path can be streamlined.

Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Dominik Brodowski <linux@xxxxxxxxxxxxxxxxxxxx>
---
arch/mips/kernel/linux32.c | 4 ++--
arch/parisc/kernel/sys_parisc.c | 4 ++--
arch/powerpc/kernel/sys_ppc32.c | 4 ++--
arch/s390/kernel/compat_linux.c | 4 ++--
arch/sh/kernel/sys_sh32.c | 4 ++--
arch/sparc/kernel/sys_sparc32.c | 4 ++--
arch/x86/ia32/sys_ia32.c | 8 ++++----
fs/read_write.c | 20 ++++++++++++++++----
include/linux/syscalls.h | 4 ++++
9 files changed, 36 insertions(+), 20 deletions(-)

diff --git a/arch/mips/kernel/linux32.c b/arch/mips/kernel/linux32.c
index 12421ba4318a..944f0ff8e00b 100644
--- a/arch/mips/kernel/linux32.c
+++ b/arch/mips/kernel/linux32.c
@@ -105,13 +105,13 @@ SYSCALL_DEFINE5(32_llseek, unsigned int, fd, unsigned int, offset_high,
SYSCALL_DEFINE6(32_pread, unsigned long, fd, char __user *, buf, size_t, count,
unsigned long, unused, unsigned long, a4, unsigned long, a5)
{
- return sys_pread64(fd, buf, count, merge_64(a4, a5));
+ return ksys_pread64(fd, buf, count, merge_64(a4, a5));
}

SYSCALL_DEFINE6(32_pwrite, unsigned int, fd, const char __user *, buf,
size_t, count, u32, unused, u64, a4, u64, a5)
{
- return sys_pwrite64(fd, buf, count, merge_64(a4, a5));
+ return ksys_pwrite64(fd, buf, count, merge_64(a4, a5));
}

SYSCALL_DEFINE1(32_personality, unsigned long, personality)
diff --git a/arch/parisc/kernel/sys_parisc.c b/arch/parisc/kernel/sys_parisc.c
index 3c1d788ab3ed..21179358926c 100644
--- a/arch/parisc/kernel/sys_parisc.c
+++ b/arch/parisc/kernel/sys_parisc.c
@@ -333,13 +333,13 @@ asmlinkage long parisc_ftruncate64(unsigned int fd,
asmlinkage ssize_t parisc_pread64(unsigned int fd, char __user *buf, size_t count,
unsigned int high, unsigned int low)
{
- return sys_pread64(fd, buf, count, (loff_t)high << 32 | low);
+ return ksys_pread64(fd, buf, count, (loff_t)high << 32 | low);
}

asmlinkage ssize_t parisc_pwrite64(unsigned int fd, const char __user *buf,
size_t count, unsigned int high, unsigned int low)
{
- return sys_pwrite64(fd, buf, count, (loff_t)high << 32 | low);
+ return ksys_pwrite64(fd, buf, count, (loff_t)high << 32 | low);
}

asmlinkage ssize_t parisc_readahead(int fd, unsigned int high, unsigned int low,
diff --git a/arch/powerpc/kernel/sys_ppc32.c b/arch/powerpc/kernel/sys_ppc32.c
index eb79138bd44d..bad1f3e891a4 100644
--- a/arch/powerpc/kernel/sys_ppc32.c
+++ b/arch/powerpc/kernel/sys_ppc32.c
@@ -77,13 +77,13 @@ unsigned long compat_sys_mmap2(unsigned long addr, size_t len,
compat_ssize_t compat_sys_pread64(unsigned int fd, char __user *ubuf, compat_size_t count,
u32 reg6, u32 poshi, u32 poslo)
{
- return sys_pread64(fd, ubuf, count, ((loff_t)poshi << 32) | poslo);
+ return ksys_pread64(fd, ubuf, count, ((loff_t)poshi << 32) | poslo);
}

compat_ssize_t compat_sys_pwrite64(unsigned int fd, const char __user *ubuf, compat_size_t count,
u32 reg6, u32 poshi, u32 poslo)
{
- return sys_pwrite64(fd, ubuf, count, ((loff_t)poshi << 32) | poslo);
+ return ksys_pwrite64(fd, ubuf, count, ((loff_t)poshi << 32) | poslo);
}

compat_ssize_t compat_sys_readahead(int fd, u32 r4, u32 offhi, u32 offlo, u32 count)
diff --git a/arch/s390/kernel/compat_linux.c b/arch/s390/kernel/compat_linux.c
index 0788df0443ba..a3b5adbd683f 100644
--- a/arch/s390/kernel/compat_linux.c
+++ b/arch/s390/kernel/compat_linux.c
@@ -315,7 +315,7 @@ COMPAT_SYSCALL_DEFINE5(s390_pread64, unsigned int, fd, char __user *, ubuf,
{
if ((compat_ssize_t) count < 0)
return -EINVAL;
- return sys_pread64(fd, ubuf, count, (unsigned long)high << 32 | low);
+ return ksys_pread64(fd, ubuf, count, (unsigned long)high << 32 | low);
}

COMPAT_SYSCALL_DEFINE5(s390_pwrite64, unsigned int, fd, const char __user *, ubuf,
@@ -323,7 +323,7 @@ COMPAT_SYSCALL_DEFINE5(s390_pwrite64, unsigned int, fd, const char __user *, ubu
{
if ((compat_ssize_t) count < 0)
return -EINVAL;
- return sys_pwrite64(fd, ubuf, count, (unsigned long)high << 32 | low);
+ return ksys_pwrite64(fd, ubuf, count, (unsigned long)high << 32 | low);
}

COMPAT_SYSCALL_DEFINE4(s390_readahead, int, fd, u32, high, u32, low, s32, count)
diff --git a/arch/sh/kernel/sys_sh32.c b/arch/sh/kernel/sys_sh32.c
index 4d55318e0899..9dca568509a5 100644
--- a/arch/sh/kernel/sys_sh32.c
+++ b/arch/sh/kernel/sys_sh32.c
@@ -39,13 +39,13 @@ asmlinkage int sys_sh_pipe(void)
asmlinkage ssize_t sys_pread_wrapper(unsigned int fd, char __user *buf,
size_t count, long dummy, loff_t pos)
{
- return sys_pread64(fd, buf, count, pos);
+ return ksys_pread64(fd, buf, count, pos);
}

asmlinkage ssize_t sys_pwrite_wrapper(unsigned int fd, const char __user *buf,
size_t count, long dummy, loff_t pos)
{
- return sys_pwrite64(fd, buf, count, pos);
+ return ksys_pwrite64(fd, buf, count, pos);
}

asmlinkage int sys_fadvise64_64_wrapper(int fd, u32 offset0, u32 offset1,
diff --git a/arch/sparc/kernel/sys_sparc32.c b/arch/sparc/kernel/sys_sparc32.c
index 4ceb2e591688..dc8c3f0fe3e8 100644
--- a/arch/sparc/kernel/sys_sparc32.c
+++ b/arch/sparc/kernel/sys_sparc32.c
@@ -200,7 +200,7 @@ asmlinkage compat_ssize_t sys32_pread64(unsigned int fd,
unsigned long poshi,
unsigned long poslo)
{
- return sys_pread64(fd, ubuf, count, (poshi << 32) | poslo);
+ return ksys_pread64(fd, ubuf, count, (poshi << 32) | poslo);
}

asmlinkage compat_ssize_t sys32_pwrite64(unsigned int fd,
@@ -209,7 +209,7 @@ asmlinkage compat_ssize_t sys32_pwrite64(unsigned int fd,
unsigned long poshi,
unsigned long poslo)
{
- return sys_pwrite64(fd, ubuf, count, (poshi << 32) | poslo);
+ return ksys_pwrite64(fd, ubuf, count, (poshi << 32) | poslo);
}

asmlinkage long compat_sys_readahead(int fd,
diff --git a/arch/x86/ia32/sys_ia32.c b/arch/x86/ia32/sys_ia32.c
index 91ed2c256dac..9d09812a40b9 100644
--- a/arch/x86/ia32/sys_ia32.c
+++ b/arch/x86/ia32/sys_ia32.c
@@ -179,15 +179,15 @@ COMPAT_SYSCALL_DEFINE3(x86_waitpid, compat_pid_t, pid, unsigned int __user *,
COMPAT_SYSCALL_DEFINE5(x86_pread, unsigned int, fd, char __user *, ubuf,
u32, count, u32, poslo, u32, poshi)
{
- return sys_pread64(fd, ubuf, count,
- ((loff_t)AA(poshi) << 32) | AA(poslo));
+ return ksys_pread64(fd, ubuf, count,
+ ((loff_t)AA(poshi) << 32) | AA(poslo));
}

COMPAT_SYSCALL_DEFINE5(x86_pwrite, unsigned int, fd, const char __user *, ubuf,
u32, count, u32, poslo, u32, poshi)
{
- return sys_pwrite64(fd, ubuf, count,
- ((loff_t)AA(poshi) << 32) | AA(poslo));
+ return ksys_pwrite64(fd, ubuf, count,
+ ((loff_t)AA(poshi) << 32) | AA(poslo));
}

diff --git a/fs/read_write.c b/fs/read_write.c
index fc441e1ac683..c4eabbfc90df 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -610,8 +610,8 @@ SYSCALL_DEFINE3(write, unsigned int, fd, const char __user *, buf,
return ksys_write(fd, buf, count);
}

-SYSCALL_DEFINE4(pread64, unsigned int, fd, char __user *, buf,
- size_t, count, loff_t, pos)
+ssize_t ksys_pread64(unsigned int fd, char __user *buf, size_t count,
+ loff_t pos)
{
struct fd f;
ssize_t ret = -EBADF;
@@ -630,8 +630,14 @@ SYSCALL_DEFINE4(pread64, unsigned int, fd, char __user *, buf,
return ret;
}

-SYSCALL_DEFINE4(pwrite64, unsigned int, fd, const char __user *, buf,
- size_t, count, loff_t, pos)
+SYSCALL_DEFINE4(pread64, unsigned int, fd, char __user *, buf,
+ size_t, count, loff_t, pos)
+{
+ return ksys_pread64(fd, buf, count, pos);
+}
+
+ssize_t ksys_pwrite64(unsigned int fd, const char __user *buf,
+ size_t count, loff_t pos)
{
struct fd f;
ssize_t ret = -EBADF;
@@ -650,6 +656,12 @@ SYSCALL_DEFINE4(pwrite64, unsigned int, fd, const char __user *, buf,
return ret;
}

+SYSCALL_DEFINE4(pwrite64, unsigned int, fd, const char __user *, buf,
+ size_t, count, loff_t, pos)
+{
+ return ksys_pwrite64(fd, buf, count, pos);
+}
+
static ssize_t do_iter_readv_writev(struct file *filp, struct iov_iter *iter,
loff_t *ppos, int type, rwf_t flags)
{
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 535cc3cf516a..73a55d8982b6 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -978,6 +978,10 @@ int ksys_ioctl(unsigned int fd, unsigned int cmd, unsigned long arg);
off_t ksys_lseek(unsigned int fd, off_t offset, unsigned int whence);
ssize_t ksys_read(unsigned int fd, char __user *buf, size_t count);
void ksys_sync(void);
+ssize_t ksys_pread64(unsigned int fd, char __user *buf, size_t count,
+ loff_t pos);
+ssize_t ksys_pwrite64(unsigned int fd, const char __user *buf,
+ size_t count, loff_t pos);

/*
* The following kernel syscall equivalents are just wrappers to fs-internal
--
2.16.2

Next message: Dominik Brodowski: "[PATCH 14/45] fs: add do_compat_signalfd4() helper; remove in-kernel call to comapt syscall"
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Next in thread: Dominik Brodowski: "[PATCH 14/45] fs: add do_compat_signalfd4() helper; remove in-kernel call to comapt syscall"
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