On 2022-02-09 1:24 p.m., Helge Deller wrote:
After commit 4b9d2a731c3d ("parisc: Switch user access functions
to signal errors in r29 instead of r8") bash suddenly started
to report those warnings after login:
-bash: cannot set terminal process group (-1): Bad file descriptor
-bash: no job control in this shell
It turned out, that another function call inside a put_user(), e.g.:
put_user(vt_do_kdgkbmode(console), (int __user *)arg);
clobbered the error register (r29) and thus failed.
Avoid this miscompilation by first calculate the value in
__put_user() before calling __put_user_internal() to actually
write the value to user space.
Couldn't the same issue occur with ptr argument in these macros?
Additionally, prefer the "+" constraint on pu_err and gu_err registers to tell
the compiler that those operands are both read and written by the assembly
instruction.
Signed-off-by: Helge Deller <deller@xxxxxx>
Fixes: 4b9d2a731c3d ("parisc: Switch user access functions to signal errors in r29 instead of r8")
diff --git a/arch/parisc/include/asm/uaccess.h b/arch/parisc/include/asm/uaccess.h
index ebf8a845b017..68f5c1eaaa6f 100644
--- a/arch/parisc/include/asm/uaccess.h
+++ b/arch/parisc/include/asm/uaccess.h
@@ -89,7 +89,7 @@ struct exception_table_entry {
__asm__("1: " ldx " 0(" sr "%2),%0\n" \
"9:\n" \
ASM_EXCEPTIONTABLE_ENTRY_EFAULT(1b, 9b) \
- : "=r"(__gu_val), "=r"(__gu_err) \
+ : "=&r"(__gu_val), "+r"(__gu_err) \
I don't believe the early clobber is needed on __gnu_val.
: "r"(ptr), "1"(__gu_err)); \
\
(val) = (__force __typeof__(*(ptr))) __gu_val; \
@@ -123,7 +123,7 @@ struct exception_table_entry {
"9:\n" \
ASM_EXCEPTIONTABLE_ENTRY_EFAULT(1b, 9b) \
ASM_EXCEPTIONTABLE_ENTRY_EFAULT(2b, 9b) \
- : "=&r"(__gu_tmp.l), "=r"(__gu_err) \
+ : "=&r"(__gu_tmp.l), "+r"(__gu_err) \
: "r"(ptr), "1"(__gu_err)); \
\
(val) = __gu_tmp.t; \
@@ -132,10 +132,9 @@ struct exception_table_entry {
#endif /* !defined(CONFIG_64BIT) */
-#define __put_user_internal(sr, x, ptr) \
+#define __put_user_internal(sr, __x, ptr) \
({ \
ASM_EXCEPTIONTABLE_VAR(__pu_err); \
- __typeof__(*(ptr)) __x = (__typeof__(*(ptr)))(x); \
\
switch (sizeof(*(ptr))) { \
case 1: __put_user_asm(sr, "stb", __x, ptr); break; \
@@ -150,7 +149,9 @@ struct exception_table_entry {
#define __put_user(x, ptr) \
({ \
- __put_user_internal("%%sr3,", x, ptr); \
+ __typeof__(*(ptr)) __x = (__typeof__(*(ptr)))(x); \
Whitespace?
+ \
+ __put_user_internal("%%sr3,", __x, ptr); \
})
#define __put_kernel_nofault(dst, src, type, err_label) \
@@ -180,7 +181,7 @@ struct exception_table_entry {
"1: " stx " %2,0(" sr "%1)\n" \
"9:\n" \
ASM_EXCEPTIONTABLE_ENTRY_EFAULT(1b, 9b) \
- : "=r"(__pu_err) \
+ : "+r"(__pu_err) \
: "r"(ptr), "r"(x), "0"(__pu_err))
@@ -193,7 +194,7 @@ struct exception_table_entry {
"9:\n" \
ASM_EXCEPTIONTABLE_ENTRY_EFAULT(1b, 9b) \
ASM_EXCEPTIONTABLE_ENTRY_EFAULT(2b, 9b) \
- : "=r"(__pu_err) \
+ : "+r"(__pu_err) \
: "r"(ptr), "r"(__val), "0"(__pu_err)); \
} while (0)
Dave
--
John David Anglin dave.anglin@xxxxxxxx
