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authorAnton Ivanov <anton.ivanov@cambridgegreys.com>2018-11-22 14:45:13 +0000
committerRichard Weinberger <richard@nod.at>2018-12-27 22:48:20 +0100
commit747b254ca2649d0c206385c7902fb8ac97a2b0b4 (patch)
treeec37d6dde343cf0e24f9f063adf41e5798c517e1 /arch/um/kernel
parent50109b5a03b4024eb6b8df3ab8f427625f54fe92 (diff)
downloadlinux-747b254ca2649d0c206385c7902fb8ac97a2b0b4.tar.bz2
um: Remove unnecessary faulted check in uaccess.c
It is not necessary to check if a fault has occured or not after disabling pagefaults. kmap_atomic does that in all cases and we can disable it for 64 bit where kmap is not needed and a simple page_address would suffice. dd if=/dev/zero of=/dev/null bs=1M count=1M Before: 3.1GB/s. After: 3.5GB/s There is a noticeable difference for file disk read and write as well as less noticeable difference for network IO. Signed-off-by: Anton Ivanov <anton.ivanov@cambridgegreys.com> Signed-off-by: Richard Weinberger <richard@nod.at>
Diffstat (limited to 'arch/um/kernel')
-rw-r--r--arch/um/kernel/skas/uaccess.c23
1 files changed, 12 insertions, 11 deletions
diff --git a/arch/um/kernel/skas/uaccess.c b/arch/um/kernel/skas/uaccess.c
index d450797a3a7c..7f06fdbc7ee1 100644
--- a/arch/um/kernel/skas/uaccess.c
+++ b/arch/um/kernel/skas/uaccess.c
@@ -62,27 +62,28 @@ static int do_op_one_page(unsigned long addr, int len, int is_write,
jmp_buf buf;
struct page *page;
pte_t *pte;
- int n, faulted;
+ int n;
pte = maybe_map(addr, is_write);
if (pte == NULL)
return -1;
page = pte_page(*pte);
+#ifdef CONFIG_64BIT
+ pagefault_disable();
+ addr = (unsigned long) page_address(page) +
+ (addr & ~PAGE_MASK);
+#else
addr = (unsigned long) kmap_atomic(page) +
(addr & ~PAGE_MASK);
+#endif
+ n = (*op)(addr, len, arg);
- current->thread.fault_catcher = &buf;
-
- faulted = UML_SETJMP(&buf);
- if (faulted == 0)
- n = (*op)(addr, len, arg);
- else
- n = -1;
-
- current->thread.fault_catcher = NULL;
-
+#ifdef CONFIG_64BIT
+ pagefault_enable();
+#else
kunmap_atomic((void *)addr);
+#endif
return n;
}