get rid of legacy 'get_ds()' function

Every in-kernel use of this function defined it to KERNEL_DS (either as
an actual define, or as an inline function).  It's an entirely
historical artifact, and long long long ago used to actually read the
segment selector valueof '%ds' on x86.

Which in the kernel is always KERNEL_DS.

Inspired by a patch from Jann Horn that just did this for a very small
subset of users (the ones in fs/), along with Al who suggested a script.
I then just took it to the logical extreme and removed all the remaining
gunk.

Roughly scripted with

   git grep -l '(get_ds())' -- :^tools/ | xargs sed -i 's/(get_ds())/(KERNEL_DS)/'
   git grep -lw 'get_ds' -- :^tools/ | xargs sed -i '/^#define get_ds()/d'

plus manual fixups to remove a few unusual usage patterns, the couple of
inline function cases and to fix up a comment that had become stale.

The 'get_ds()' function remains in an x86 kvm selftest, since in user
space it actually does something relevant.

Inspired-by: Jann Horn <jannh@google.com>
Inspired-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

28 files changed, 9 insertions, 44 deletions

diff --git a/arch/alpha/include/asm/uaccess.h b/arch/alpha/include/asm/uaccess.h
index cf4ac791a592..1fe2b56cb861 100644
--- a/arch/alpha/include/asm/uaccess.h
+++ b/arch/alpha/include/asm/uaccess.h
@@ -18,7 +18,6 @@
 #define USER_DS		((mm_segment_t) { -0x40000000000UL })
 
 #define get_fs()  (current_thread_info()->addr_limit)
-#define get_ds()  (KERNEL_DS)
 #define set_fs(x) (current_thread_info()->addr_limit = (x))
 
 #define segment_eq(a, b)	((a).seg == (b).seg)
diff --git a/arch/arm/include/asm/uaccess.h b/arch/arm/include/asm/uaccess.h
index 42aa4a22803c..ae5a0df5316e 100644
--- a/arch/arm/include/asm/uaccess.h
+++ b/arch/arm/include/asm/uaccess.h
@@ -59,7 +59,6 @@ extern int __put_user_bad(void);
  * Note that this is actually 0x1,0000,0000
  */
 #define KERNEL_DS	0x00000000
-#define get_ds()	(KERNEL_DS)
 
 #ifdef CONFIG_MMU
 
diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index 16601d1442d1..72cc0862a30e 100644
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -150,7 +150,7 @@ void __show_regs(struct pt_regs *regs)
 		if ((domain & domain_mask(DOMAIN_USER)) ==
 		    domain_val(DOMAIN_USER, DOMAIN_NOACCESS))
 			segment = "none";
-		else if (fs == get_ds())
+		else if (fs == KERNEL_DS)
 			segment = "kernel";
 		else
 			segment = "user";
diff --git a/arch/arm/xen/hypercall.S b/arch/arm/xen/hypercall.S
index b0b80c0f09f3..b11bba542fac 100644
--- a/arch/arm/xen/hypercall.S
+++ b/arch/arm/xen/hypercall.S
@@ -113,8 +113,7 @@ ENTRY(privcmd_call)
 
 	/*
 	 * Disable userspace access from kernel. This is fine to do it
-	 * unconditionally as no set_fs(KERNEL_DS)/set_fs(get_ds()) is
-	 * called before.
+	 * unconditionally as no set_fs(KERNEL_DS) is called before.
 	 */
 	uaccess_disable r4
 
diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
index 547d7a0c9d05..f1e5c9165809 100644
--- a/arch/arm64/include/asm/uaccess.h
+++ b/arch/arm64/include/asm/uaccess.h
@@ -34,7 +34,6 @@
 #include <asm/memory.h>
 #include <asm/extable.h>
 
-#define get_ds()	(KERNEL_DS)
 #define get_fs()	(current_thread_info()->addr_limit)
 
 static inline void set_fs(mm_segment_t fs)
diff --git a/arch/csky/include/asm/segment.h b/arch/csky/include/asm/segment.h
index ffdc4c47ff43..db2640d5f575 100644
--- a/arch/csky/include/asm/segment.h
+++ b/arch/csky/include/asm/segment.h
@@ -9,7 +9,6 @@ typedef struct {
 } mm_segment_t;
 
 #define KERNEL_DS		((mm_segment_t) { 0xFFFFFFFF })
-#define get_ds()		KERNEL_DS
 
 #define USER_DS			((mm_segment_t) { 0x80000000UL })
 #define get_fs()		(current_thread_info()->addr_limit)
diff --git a/arch/h8300/include/asm/segment.h b/arch/h8300/include/asm/segment.h
index 9adbf7e1aaa3..a407978f9f9f 100644
--- a/arch/h8300/include/asm/segment.h
+++ b/arch/h8300/include/asm/segment.h
@@ -33,12 +33,6 @@ static inline mm_segment_t get_fs(void)
 	return USER_DS;
 }
 
-static inline mm_segment_t get_ds(void)
-{
-	/* return the supervisor data space code */
-	return KERNEL_DS;
-}
-
 #define segment_eq(a, b)	((a).seg == (b).seg)
 
 #endif /* __ASSEMBLY__ */
diff --git a/arch/ia64/include/asm/uaccess.h b/arch/ia64/include/asm/uaccess.h
index 306d469e43da..89782ad3fb88 100644
--- a/arch/ia64/include/asm/uaccess.h
+++ b/arch/ia64/include/asm/uaccess.h
@@ -48,7 +48,6 @@
 #define KERNEL_DS	((mm_segment_t) { ~0UL })		/* cf. access_ok() */
 #define USER_DS		((mm_segment_t) { TASK_SIZE-1 })	/* cf. access_ok() */
 
-#define get_ds()  (KERNEL_DS)
 #define get_fs()  (current_thread_info()->addr_limit)
 #define set_fs(x) (current_thread_info()->addr_limit = (x))
 
diff --git a/arch/m68k/include/asm/segment.h b/arch/m68k/include/asm/segment.h
index 0b4cc1e079b5..c6686559e9b7 100644
--- a/arch/m68k/include/asm/segment.h
+++ b/arch/m68k/include/asm/segment.h
@@ -45,16 +45,9 @@ static inline void set_fs(mm_segment_t val)
 			      : /* no outputs */ : "r" (val.seg) : "memory");
 }
 
-static inline mm_segment_t get_ds(void)
-{
-    /* return the supervisor data space code */
-    return KERNEL_DS;
-}
-
 #else
 #define USER_DS		MAKE_MM_SEG(TASK_SIZE)
 #define KERNEL_DS	MAKE_MM_SEG(0xFFFFFFFF)
-#define get_ds()	(KERNEL_DS)
 #define get_fs()	(current_thread_info()->addr_limit)
 #define set_fs(x)	(current_thread_info()->addr_limit = (x))
 #endif
diff --git a/arch/microblaze/include/asm/uaccess.h b/arch/microblaze/include/asm/uaccess.h
index dbfea093a7c7..bff2a71c828a 100644
--- a/arch/microblaze/include/asm/uaccess.h
+++ b/arch/microblaze/include/asm/uaccess.h
@@ -42,7 +42,6 @@
 #  define USER_DS	MAKE_MM_SEG(TASK_SIZE - 1)
 #  endif
 
-# define get_ds()	(KERNEL_DS)
 # define get_fs()	(current_thread_info()->addr_limit)
 # define set_fs(val)	(current_thread_info()->addr_limit = (val))
 
diff --git a/arch/mips/include/asm/uaccess.h b/arch/mips/include/asm/uaccess.h
index d43c1dc6ef15..62b298c50905 100644
--- a/arch/mips/include/asm/uaccess.h
+++ b/arch/mips/include/asm/uaccess.h
@@ -69,7 +69,6 @@ extern u64 __ua_limit;
 #define USER_DS		((mm_segment_t) { __UA_LIMIT })
 #endif
 
-#define get_ds()	(KERNEL_DS)
 #define get_fs()	(current_thread_info()->addr_limit)
 #define set_fs(x)	(current_thread_info()->addr_limit = (x))
 
diff --git a/arch/mips/kernel/ftrace.c b/arch/mips/kernel/ftrace.c
index 2ea0ec95efe9..4b5e1f2bfbce 100644
--- a/arch/mips/kernel/ftrace.c
+++ b/arch/mips/kernel/ftrace.c
@@ -86,7 +86,7 @@ static int ftrace_modify_code(unsigned long ip, unsigned int new_code)
 		return -EFAULT;
 
 	old_fs = get_fs();
-	set_fs(get_ds());
+	set_fs(KERNEL_DS);
 	flush_icache_range(ip, ip + 8);
 	set_fs(old_fs);
 
@@ -111,7 +111,7 @@ static int ftrace_modify_code_2(unsigned long ip, unsigned int new_code1,
 
 	ip -= 4;
 	old_fs = get_fs();
-	set_fs(get_ds());
+	set_fs(KERNEL_DS);
 	flush_icache_range(ip, ip + 8);
 	set_fs(old_fs);
 
@@ -135,7 +135,7 @@ static int ftrace_modify_code_2r(unsigned long ip, unsigned int new_code1,
 		return -EFAULT;
 
 	old_fs = get_fs();
-	set_fs(get_ds());
+	set_fs(KERNEL_DS);
 	flush_icache_range(ip, ip + 8);
 	set_fs(old_fs);
 
diff --git a/arch/mips/kernel/kgdb.c b/arch/mips/kernel/kgdb.c
index 149100e1bc7c..6e574c02e4c3 100644
--- a/arch/mips/kernel/kgdb.c
+++ b/arch/mips/kernel/kgdb.c
@@ -212,7 +212,7 @@ void kgdb_call_nmi_hook(void *ignored)
 	mm_segment_t old_fs;
 
 	old_fs = get_fs();
-	set_fs(get_ds());
+	set_fs(KERNEL_DS);
 
 	kgdb_nmicallback(raw_smp_processor_id(), NULL);
 
@@ -318,7 +318,7 @@ static int kgdb_mips_notify(struct notifier_block *self, unsigned long cmd,
 
 	/* Kernel mode. Set correct address limit */
 	old_fs = get_fs();
-	set_fs(get_ds());
+	set_fs(KERNEL_DS);
 
 	if (atomic_read(&kgdb_active) != -1)
 		kgdb_nmicallback(smp_processor_id(), regs);
diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c
index c91097f7b32f..cbab46004e99 100644
--- a/arch/mips/kernel/traps.c
+++ b/arch/mips/kernel/traps.c
@@ -1077,7 +1077,7 @@ asmlinkage void do_tr(struct pt_regs *regs)
 
 	seg = get_fs();
 	if (!user_mode(regs))
-		set_fs(get_ds());
+		set_fs(KERNEL_DS);
 
 	prev_state = exception_enter();
 	current->thread.trap_nr = (regs->cp0_cause >> 2) & 0x1f;
diff --git a/arch/nds32/include/asm/uaccess.h b/arch/nds32/include/asm/uaccess.h
index 53dcb49b0b12..116598b47c4d 100644
--- a/arch/nds32/include/asm/uaccess.h
+++ b/arch/nds32/include/asm/uaccess.h
@@ -37,7 +37,6 @@ extern int fixup_exception(struct pt_regs *regs);
 #define KERNEL_DS 	((mm_segment_t) { ~0UL })
 #define USER_DS		((mm_segment_t) {TASK_SIZE - 1})
 
-#define get_ds()	(KERNEL_DS)
 #define get_fs()	(current_thread_info()->addr_limit)
 #define user_addr_max	get_fs
 
diff --git a/arch/nds32/kernel/process.c b/arch/nds32/kernel/process.c
index ab7ab46234b1..9712fd474f2c 100644
--- a/arch/nds32/kernel/process.c
+++ b/arch/nds32/kernel/process.c
@@ -121,7 +121,7 @@ void show_regs(struct pt_regs *regs)
 		regs->uregs[3], regs->uregs[2], regs->uregs[1], regs->uregs[0]);
 	pr_info("  IRQs o%s  Segment %s\n",
 		interrupts_enabled(regs) ? "n" : "ff",
-		segment_eq(get_fs(), get_ds())? "kernel" : "user");
+		segment_eq(get_fs(), KERNEL_DS)? "kernel" : "user");
 }
 
 EXPORT_SYMBOL(show_regs);
diff --git a/arch/nios2/include/asm/uaccess.h b/arch/nios2/include/asm/uaccess.h
index e0ea10806491..e83f831a76f9 100644
--- a/arch/nios2/include/asm/uaccess.h
+++ b/arch/nios2/include/asm/uaccess.h
@@ -26,7 +26,6 @@
 #define USER_DS			MAKE_MM_SEG(0x80000000UL)
 #define KERNEL_DS		MAKE_MM_SEG(0)
 
-#define get_ds()		(KERNEL_DS)
 
 #define get_fs()		(current_thread_info()->addr_limit)
 #define set_fs(seg)		(current_thread_info()->addr_limit = (seg))
diff --git a/arch/openrisc/include/asm/uaccess.h b/arch/openrisc/include/asm/uaccess.h
index a44682c8adc3..45afd9ab78c1 100644
--- a/arch/openrisc/include/asm/uaccess.h
+++ b/arch/openrisc/include/asm/uaccess.h
@@ -42,7 +42,6 @@
  */
 
 #define KERNEL_DS	(~0UL)
-#define get_ds()	(KERNEL_DS)
 
 #define USER_DS		(TASK_SIZE)
 #define get_fs()	(current_thread_info()->addr_limit)
diff --git a/arch/parisc/include/asm/uaccess.h b/arch/parisc/include/asm/uaccess.h
index 30ac2865ea73..ebbb9ffe038c 100644
--- a/arch/parisc/include/asm/uaccess.h
+++ b/arch/parisc/include/asm/uaccess.h
@@ -16,7 +16,6 @@
 
 #define segment_eq(a, b) ((a).seg == (b).seg)
 
-#define get_ds()	(KERNEL_DS)
 #define get_fs()	(current_thread_info()->addr_limit)
 #define set_fs(x)	(current_thread_info()->addr_limit = (x))
 
diff --git a/arch/powerpc/include/asm/uaccess.h b/arch/powerpc/include/asm/uaccess.h
index e3a731793ea2..4d6d905e9138 100644
--- a/arch/powerpc/include/asm/uaccess.h
+++ b/arch/powerpc/include/asm/uaccess.h
@@ -28,7 +28,6 @@
 #define USER_DS		MAKE_MM_SEG(TASK_SIZE - 1)
 #endif
 
-#define get_ds()	(KERNEL_DS)
 #define get_fs()	(current->thread.addr_limit)
 
 static inline void set_fs(mm_segment_t fs)
diff --git a/arch/riscv/include/asm/uaccess.h b/arch/riscv/include/asm/uaccess.h
index 637b896894fc..a00168b980d2 100644
--- a/arch/riscv/include/asm/uaccess.h
+++ b/arch/riscv/include/asm/uaccess.h
@@ -41,7 +41,6 @@
 #define KERNEL_DS	(~0UL)
 #define USER_DS		(TASK_SIZE)
 
-#define get_ds()	(KERNEL_DS)
 #define get_fs()	(current_thread_info()->addr_limit)
 
 static inline void set_fs(mm_segment_t fs)
diff --git a/arch/s390/include/asm/uaccess.h b/arch/s390/include/asm/uaccess.h
index bd2545977ad3..007fcb9aeeb8 100644
--- a/arch/s390/include/asm/uaccess.h
+++ b/arch/s390/include/asm/uaccess.h
@@ -31,7 +31,6 @@
 #define USER_DS		(2)
 #define USER_DS_SACF	(3)
 
-#define get_ds()        (KERNEL_DS)
 #define get_fs()        (current->thread.mm_segment)
 #define segment_eq(a,b) (((a) & 2) == ((b) & 2))
 
diff --git a/arch/sh/include/asm/segment.h b/arch/sh/include/asm/segment.h
index 101c13c0c6ad..33d1d28057cb 100644
--- a/arch/sh/include/asm/segment.h
+++ b/arch/sh/include/asm/segment.h
@@ -26,7 +26,6 @@ typedef struct {
 
 #define segment_eq(a, b) ((a).seg == (b).seg)
 
-#define get_ds()	(KERNEL_DS)
 
 #define get_fs()	(current_thread_info()->addr_limit)
 #define set_fs(x)	(current_thread_info()->addr_limit = (x))
diff --git a/arch/sparc/include/asm/uaccess_32.h b/arch/sparc/include/asm/uaccess_32.h
index 5153798051fb..d6d8413eca83 100644
--- a/arch/sparc/include/asm/uaccess_32.h
+++ b/arch/sparc/include/asm/uaccess_32.h
@@ -25,7 +25,6 @@
 #define KERNEL_DS   ((mm_segment_t) { 0 })
 #define USER_DS     ((mm_segment_t) { -1 })
 
-#define get_ds()	(KERNEL_DS)
 #define get_fs()	(current->thread.current_ds)
 #define set_fs(val)	((current->thread.current_ds) = (val))
 
diff --git a/arch/sparc/include/asm/uaccess_64.h b/arch/sparc/include/asm/uaccess_64.h
index 87ae9ffb1521..bf9d330073b2 100644
--- a/arch/sparc/include/asm/uaccess_64.h
+++ b/arch/sparc/include/asm/uaccess_64.h
@@ -31,7 +31,6 @@
 #define USER_DS     ((mm_segment_t) { ASI_AIUS })	/* har har har */
 
 #define get_fs() ((mm_segment_t){(current_thread_info()->current_ds)})
-#define get_ds() (KERNEL_DS)
 
 #define segment_eq(a, b)  ((a).seg == (b).seg)
 
diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
index c1334aaaa78d..5e49a0acb5ee 100644
--- a/arch/x86/include/asm/uaccess.h
+++ b/arch/x86/include/asm/uaccess.h
@@ -25,7 +25,6 @@
 #define KERNEL_DS	MAKE_MM_SEG(-1UL)
 #define USER_DS 	MAKE_MM_SEG(TASK_SIZE_MAX)
 
-#define get_ds()	(KERNEL_DS)
 #define get_fs()	(current->thread.addr_limit)
 static inline void set_fs(mm_segment_t fs)
 {
diff --git a/arch/xtensa/include/asm/asm-uaccess.h b/arch/xtensa/include/asm/asm-uaccess.h
index dfdf9fae1f84..7f6cf4151843 100644
--- a/arch/xtensa/include/asm/asm-uaccess.h
+++ b/arch/xtensa/include/asm/asm-uaccess.h
@@ -32,8 +32,6 @@
 #define KERNEL_DS	0
 #define USER_DS		1
 
-#define get_ds		(KERNEL_DS)
-
 /*
  * get_fs reads current->thread.current_ds into a register.
  * On Entry:
diff --git a/arch/xtensa/include/asm/uaccess.h b/arch/xtensa/include/asm/uaccess.h
index 4b2480304bc3..6792928ba84a 100644
--- a/arch/xtensa/include/asm/uaccess.h
+++ b/arch/xtensa/include/asm/uaccess.h
@@ -32,7 +32,6 @@
 #define KERNEL_DS	((mm_segment_t) { 0 })
 #define USER_DS		((mm_segment_t) { 1 })
 
-#define get_ds()	(KERNEL_DS)
 #define get_fs()	(current->thread.current_ds)
 #define set_fs(val)	(current->thread.current_ds = (val))