arch/alpha, termios: implement BOTHER, IBSHIFT and termios2

From: H. Peter Anvin (Intel) (hpa@xxxxxxxxx)
Date: Mon Oct 22 2018 - 12:19:05 EST


Alpha has had c_ispeed and c_ospeed, but still set speeds in c_cflags
using arbitrary flags. Because BOTHER is not defined, the general
Linux code doesn't allow setting arbitrary baud rates, and because
CBAUDEX == 0, we can have an array overrun of the baud_rate[] table in
drivers/tty/tty_baudrate.c if (c_cflags & CBAUD) == 037.

Resolve both problems by #defining BOTHER to 037 on Alpha.

However, userspace still needs to know if setting BOTHER is actually
safe given legacy kernels (does anyone actually care about that on
Alpha anymore?), so enable the TCGETS2/TCSETS*2 ioctls on Alpha, even
though they use the same structure. Define struct termios2 just for
compatibility; it is the exact same structure as struct termios. In a
future patchset, this will be cleaned up so the uapi headers are
usable from libc.

Signed-off-by: H. Peter Anvin (Intel) <hpa@xxxxxxxxx>
Cc: Jiri Slaby <jslaby@xxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Richard Henderson <rth@xxxxxxxxxxx>
Cc: Ivan Kokshaysky <ink@xxxxxxxxxxxxxxxxxxxx>
Cc: Matt Turner <mattst88@xxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Kate Stewart <kstewart@xxxxxxxxxxxxxxxxxxx>
Cc: Philippe Ombredanne <pombredanne@xxxxxxxx>
Cc: Eugene Syromiatnikov <esyr@xxxxxxxxxx>
Cc: <linux-alpha@xxxxxxxxxxxxxxx>
Cc: <linux-serial@xxxxxxxxxxxxxxx>
Cc: Johan Hovold <johan@xxxxxxxxxx>
Cc: Alan Cox <alan@xxxxxxxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/alpha/include/asm/termios.h | 8 +++++++-
arch/alpha/include/uapi/asm/ioctls.h | 5 +++++
arch/alpha/include/uapi/asm/termbits.h | 17 +++++++++++++++++
3 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/arch/alpha/include/asm/termios.h b/arch/alpha/include/asm/termios.h
index 6a8c53dec57e..b7c77bb1bfd2 100644
--- a/arch/alpha/include/asm/termios.h
+++ b/arch/alpha/include/asm/termios.h
@@ -73,9 +73,15 @@
})

#define user_termios_to_kernel_termios(k, u) \
- copy_from_user(k, u, sizeof(struct termios))
+ copy_from_user(k, u, sizeof(struct termios2))

#define kernel_termios_to_user_termios(u, k) \
+ copy_to_user(u, k, sizeof(struct termios2))
+
+#define user_termios_to_kernel_termios_1(k, u) \
+ copy_from_user(k, u, sizeof(struct termios))
+
+#define kernel_termios_to_user_termios_1(u, k) \
copy_to_user(u, k, sizeof(struct termios))

#endif /* _ALPHA_TERMIOS_H */
diff --git a/arch/alpha/include/uapi/asm/ioctls.h b/arch/alpha/include/uapi/asm/ioctls.h
index 3729d92d3fa8..dc8c20ac7191 100644
--- a/arch/alpha/include/uapi/asm/ioctls.h
+++ b/arch/alpha/include/uapi/asm/ioctls.h
@@ -32,6 +32,11 @@
#define TCXONC _IO('t', 30)
#define TCFLSH _IO('t', 31)

+#define TCGETS2 _IOR('T', 42, struct termios2)
+#define TCSETS2 _IOW('T', 43, struct termios2)
+#define TCSETSW2 _IOW('T', 44, struct termios2)
+#define TCSETSF2 _IOW('T', 45, struct termios2)
+
#define TIOCSWINSZ _IOW('t', 103, struct winsize)
#define TIOCGWINSZ _IOR('t', 104, struct winsize)
#define TIOCSTART _IO('t', 110) /* start output, like ^Q */
diff --git a/arch/alpha/include/uapi/asm/termbits.h b/arch/alpha/include/uapi/asm/termbits.h
index de6c8360fbe3..4575ba34a0ea 100644
--- a/arch/alpha/include/uapi/asm/termbits.h
+++ b/arch/alpha/include/uapi/asm/termbits.h
@@ -26,6 +26,19 @@ struct termios {
speed_t c_ospeed; /* output speed */
};

+/* Alpha has identical termios and termios2 */
+
+struct termios2 {
+ tcflag_t c_iflag; /* input mode flags */
+ tcflag_t c_oflag; /* output mode flags */
+ tcflag_t c_cflag; /* control mode flags */
+ tcflag_t c_lflag; /* local mode flags */
+ cc_t c_cc[NCCS]; /* control characters */
+ cc_t c_line; /* line discipline (== c_cc[19]) */
+ speed_t c_ispeed; /* input speed */
+ speed_t c_ospeed; /* output speed */
+};
+
/* Alpha has matching termios and ktermios */

struct ktermios {
@@ -152,6 +165,7 @@ struct ktermios {
#define B3000000 00034
#define B3500000 00035
#define B4000000 00036
+#define BOTHER 00037

#define CSIZE 00001400
#define CS5 00000000
@@ -169,6 +183,9 @@ struct ktermios {
#define CMSPAR 010000000000 /* mark or space (stick) parity */
#define CRTSCTS 020000000000 /* flow control */

+#define CIBAUD 07600000
+#define IBSHIFT 16
+
/* c_lflag bits */
#define ISIG 0x00000080
#define ICANON 0x00000100
--
2.19.1