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Davide Libenzi
Dec 9, 2015, 10:33:44 PM12/9/15
to Akaros
This moves the user memcpy inline asm to an uaccess.c file, to avoid GCC messing up with ECX loading.
The following changes since commit 2fa42319139e4cc5ca853546363f84443d0ead00:
Rename 'reallocarray' to 'kreallocarray'. (2015-11-25 18:02:04 -0500)
are available in the git repository at:
g...@github.com:dlibenzi/akaros gcc_fuggetaboud_ecx
for you to fetch changes up to 93d0ee92f6a3fee03e149a7462f17277c386cbda:
Fix nasty GCC bug where ECX was forgotten (2015-12-09 19:29:11 -0800)
----------------------------------------------------------------
Davide Libenzi (1):
Fix nasty GCC bug where ECX was forgotten
kern/arch/x86/Kbuild | 1 +
kern/arch/x86/uaccess.c | 26 ++++++++++++++++++++++++++
kern/arch/x86/uaccess.h | 11 +++++++----
3 files changed, 34 insertions(+), 4 deletions(-)
create mode 100644 kern/arch/x86/uaccess.c
diff --git a/kern/arch/x86/Kbuild b/kern/arch/x86/Kbuild
index ae25726..cbc4e65 100644
--- a/kern/arch/x86/Kbuild
+++ b/kern/arch/x86/Kbuild
@@ -31,4 +31,5 @@ obj-y += trap.o trap64.o
obj-y += trapentry64.o
obj-y += usb.o
obj-y += topology.o
+obj-y += uaccess.o
obj-y += vmm/
diff --git a/kern/arch/x86/uaccess.c b/kern/arch/x86/uaccess.c
new file mode 100644
index 0000000..6d13924
--- /dev/null
+++ b/kern/arch/x86/uaccess.c
@@ -0,0 +1,26 @@
+/* Copyright (c) 2015 Google Inc
+ * Davide Libenzi <dlib...@google.com>
+ * See LICENSE for details.
+ *
+ * Part of this code coming from a Linux kernel file:
+ *
+ * linux/arch/x86/include/asm/uaccess.h
+ *
+ * Which, even though missing specific copyright, it is supposed to be
+ * ruled by the overall Linux copyright.
+ */
+
+#include <ros/errno.h>
+#include <compiler.h>
+#include <stdint.h>
+#include <umem.h>
+#include <arch/uaccess.h>
+
+int user_memcpy(void *dst, const void *src, unsigned int count)
+{
+ int err = 0;
+
+ __user_memcpy(dst, src, count, err, -EFAULT);
+
+ return err;
+}
diff --git a/kern/arch/x86/uaccess.h b/kern/arch/x86/uaccess.h
index cba0ef5..d5f1ea3 100644
--- a/kern/arch/x86/uaccess.h
+++ b/kern/arch/x86/uaccess.h
@@ -94,6 +94,7 @@ struct extable_ip_fixup {
#define __user_memcpy(dst, src, count, err, errret) \
asm volatile(ASM_STAC "\n" \
+ " cld\n" \
"1: rep movsb\n" \
"2: " ASM_CLAC "\n" \
".section .fixup,\"ax\"\n" \
@@ -105,6 +106,8 @@ struct extable_ip_fixup {
: "D" (dst), "S" (src), "c" (count), "i" (errret), "0" (err) \
: "memory")
+int user_memcpy(void *dst, const void *src, unsigned int count);
+
static inline int __put_user(void *dst, const void *src, unsigned int count)
{
int err = 0;
@@ -127,7 +130,7 @@ static inline int __put_user(void *dst, const void *src, unsigned int count)
"", "er", -EFAULT);
break;
default:
- __user_memcpy(dst, src, count, err, -EFAULT);
+ err = user_memcpy(dst, src, count);
}
return err;
@@ -140,7 +143,7 @@ static inline int copy_to_user(void *dst, const void *src, unsigned int count)
if (unlikely(!is_user_rwaddr(dst, count))) {
err = -EFAULT;
} else if (!__builtin_constant_p(count)) {
- __user_memcpy(dst, src, count, err, -EFAULT);
+ err = user_memcpy(dst, src, count);
} else {
err = __put_user(dst, src, count);
}
@@ -170,7 +173,7 @@ static inline int __get_user(void *dst, const void *src, unsigned int count)
"", "=r", -EFAULT);
break;
default:
- __user_memcpy(dst, src, count, err, -EFAULT);
+ err = user_memcpy(dst, src, count);
}
return err;
@@ -184,7 +187,7 @@ static inline int copy_from_user(void *dst, const void *src,
if (unlikely(!is_user_raddr((void *) src, count))) {
err = -EFAULT;
} else if (!__builtin_constant_p(count)) {
- __user_memcpy(dst, src, count, err, -EFAULT);
+ err = user_memcpy(dst, src, count);
} else {
err = __get_user(dst, src, count);
}
Davide Libenzi
Dec 9, 2015, 10:54:03 PM12/9/15
to Akaros
Hold on.
This is one solution.
Adding ecx, esi, edi in the clobber will not work, as they are inputs, so alternative proposal follows ...
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