[PATCH 7/7] m68k: remove set_fs()

Christoph Hellwig
2021-07-09T07:02:34Z

Add a m68k-only set_fc helper to set the SFC and DFC registers for the
few places that need to override it for special MM operations, but
disconnect that from the deprecated kernel-wide set_fs() API.

Note that the SFC/DFC registers are context switched, so there is no need
to disable preemption.

Partially based on an earlier patch from
Linus Torvalds <torvalds@linux-foundation.org>.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
arch/m68k/68000/entry.S | 1 -
arch/m68k/Kconfig | 1 -
arch/m68k/coldfire/entry.S | 1 -
arch/m68k/include/asm/processor.h | 31 +++++++++++++--
arch/m68k/include/asm/segment.h | 59 -----------------------------
arch/m68k/include/asm/thread_info.h | 3 --
arch/m68k/include/asm/tlbflush.h | 11 ++----
arch/m68k/include/asm/uaccess.h | 4 --
arch/m68k/kernel/asm-offsets.c | 2 +-
arch/m68k/kernel/entry.S | 5 +--
arch/m68k/kernel/process.c | 4 +-
arch/m68k/kernel/traps.c | 13 ++-----
arch/m68k/mac/misc.c | 1 -
arch/m68k/mm/cache.c | 23 ++++++-----
arch/m68k/mm/init.c | 2 +-
arch/m68k/mm/kmap.c | 1 -
arch/m68k/mm/memory.c | 1 -
arch/m68k/mm/motorola.c | 2 +-
arch/m68k/sun3/config.c | 3 +-
arch/m68k/sun3/mmu_emu.c | 6 +--
arch/m68k/sun3/sun3ints.c | 1 -
arch/m68k/sun3x/prom.c | 1 -
22 files changed, 59 insertions(+), 117 deletions(-)
delete mode 100644 arch/m68k/include/asm/segment.h

diff --git a/arch/m68k/68000/entry.S b/arch/m68k/68000/entry.S
index 259b3661b614..6aefcc20c28a 100644
--- a/arch/m68k/68000/entry.S
+++ b/arch/m68k/68000/entry.S
@@ -15,7 +15,6 @@
#include <asm/unistd.h>
#include <asm/errno.h>
#include <asm/setup.h>
-#include <asm/segment.h>
#include <asm/traps.h>
#include <asm/asm-offsets.h>
#include <asm/entry.h>
diff --git a/arch/m68k/Kconfig b/arch/m68k/Kconfig
index 96989ad46f66..3a83013f0a96 100644
--- a/arch/m68k/Kconfig
+++ b/arch/m68k/Kconfig
@@ -32,7 +32,6 @@ config M68K
select NO_DMA if !MMU && !COLDFIRE
select OLD_SIGACTION
select OLD_SIGSUSPEND3
- select SET_FS
select UACCESS_MEMCPY if !MMU
select VIRT_TO_BUS
select ZONE_DMA
diff --git a/arch/m68k/coldfire/entry.S b/arch/m68k/coldfire/entry.S
index d43a02795a4a..412bb7326099 100644
--- a/arch/m68k/coldfire/entry.S
+++ b/arch/m68k/coldfire/entry.S
@@ -31,7 +31,6 @@
#include <asm/thread_info.h>
#include <asm/errno.h>
#include <asm/setup.h>
-#include <asm/segment.h>
#include <asm/asm-offsets.h>
#include <asm/entry.h>

diff --git a/arch/m68k/include/asm/processor.h b/arch/m68k/include/asm/processor.h
index 3750819ac5a1..debb4537eab5 100644
--- a/arch/m68k/include/asm/processor.h
+++ b/arch/m68k/include/asm/processor.h
@@ -9,7 +9,6 @@
#define __ASM_M68K_PROCESSOR_H

#include <linux/thread_info.h>
-#include <asm/segment.h>
#include <asm/fpu.h>
#include <asm/ptrace.h>

@@ -75,11 +74,37 @@ static inline void wrusp(unsigned long usp)
#define TASK_UNMAPPED_BASE 0
#endif

+/* Address spaces (or Function Codes in Motorola lingo) */
+#define USER_DATA (1)
+#define USER_PROGRAM (2)
+#define SUPER_DATA (5)
+#define SUPER_PROGRAM (6)
+#define CPU_SPACE (7)
+
+#ifdef CONFIG_CPU_HAS_ADDRESS_SPACES
+/*
+ * Set the SFC/DFC registers for special MM operations. For most normal
+ * operation these remain set to USER_DATA for the uaccess routines.
+ */
+static inline void set_fc(unsigned long val)
+{
+ WARN_ON_ONCE(in_interrupt());
+
+ __asm__ __volatile__ ("movec %0,%/sfc\n\t"
+ "movec %0,%/dfc\n\t"
+ : /* no outputs */ : "r" (val) : "memory");
+}
+#else
+static inline void set_fc(unsigned long val)
+{
+}
+#endif /* CONFIG_CPU_HAS_ADDRESS_SPACES */
+
struct thread_struct {
unsigned long ksp; /* kernel stack pointer */
unsigned long usp; /* user stack pointer */
unsigned short sr; /* saved status register */
- unsigned short fs; /* saved fs (sfc, dfc) */
+ unsigned short fc; /* saved fc (sfc, dfc) */
unsigned long crp[2]; /* cpu root pointer */
unsigned long esp0; /* points to SR of stack frame */
unsigned long faddr; /* info about last fault */
@@ -92,7 +117,7 @@ struct thread_struct {
#define INIT_THREAD { \
.ksp = sizeof(init_stack) + (unsigned long) init_stack, \
.sr = PS_S, \
- .fs = __KERNEL_DS, \
+ .fc = USER_DATA, \
}

/*
diff --git a/arch/m68k/include/asm/segment.h b/arch/m68k/include/asm/segment.h
deleted file mode 100644
index 2b5e68a71ef7..000000000000
--- a/arch/m68k/include/asm/segment.h
+++ /dev/null
@@ -1,59 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-#ifndef _M68K_SEGMENT_H
-#define _M68K_SEGMENT_H
-
-/* define constants */
-/* Address spaces (FC0-FC2) */
-#define USER_DATA (1)
-#ifndef __USER_DS
-#define __USER_DS (USER_DATA)
-#endif
-#define USER_PROGRAM (2)
-#define SUPER_DATA (5)
-#ifndef __KERNEL_DS
-#define __KERNEL_DS (SUPER_DATA)
-#endif
-#define SUPER_PROGRAM (6)
-#define CPU_SPACE (7)
-
-#ifndef __ASSEMBLY__
-
-typedef struct {
- unsigned long seg;
-} mm_segment_t;
-
-#define MAKE_MM_SEG(s) ((mm_segment_t) { (s) })
-
-#ifdef CONFIG_CPU_HAS_ADDRESS_SPACES
-/*
- * Get/set the SFC/DFC registers for MOVES instructions
- */
-#define USER_DS MAKE_MM_SEG(__USER_DS)
-#define KERNEL_DS MAKE_MM_SEG(__KERNEL_DS)
-
-static inline mm_segment_t get_fs(void)
-{
- mm_segment_t _v;
- __asm__ ("movec %/dfc,%0":"=r" (_v.seg):);
- return _v;
-}
-
-static inline void set_fs(mm_segment_t val)
-{
- __asm__ __volatile__ ("movec %0,%/sfc\n\t"
- "movec %0,%/dfc\n\t"
- : /* no outputs */ : "r" (val.seg) : "memory");
-}
-
-#else
-#define USER_DS MAKE_MM_SEG(TASK_SIZE)
-#define KERNEL_DS MAKE_MM_SEG(0xFFFFFFFF)
-#define get_fs() (current_thread_info()->addr_limit)
-#define set_fs(x) (current_thread_info()->addr_limit = (x))
-#endif
-
-#define uaccess_kernel() (get_fs().seg == KERNEL_DS.seg)
-
-#endif /* __ASSEMBLY__ */
-
-#endif /* _M68K_SEGMENT_H */
diff --git a/arch/m68k/include/asm/thread_info.h b/arch/m68k/include/asm/thread_info.h
index 15a757073fa5..c952658ba792 100644
--- a/arch/m68k/include/asm/thread_info.h
+++ b/arch/m68k/include/asm/thread_info.h
@@ -4,7 +4,6 @@

#include <asm/types.h>
#include <asm/page.h>
-#include <asm/segment.h>

/*
* On machines with 4k pages we default to an 8k thread size, though we
@@ -27,7 +26,6 @@
struct thread_info {
struct task_struct *task; /* main task structure */
unsigned long flags;
- mm_segment_t addr_limit; /* thread address space */
int preempt_count; /* 0 => preemptable, <0 => BUG */
__u32 cpu; /* should always be 0 on m68k */
unsigned long tp_value; /* thread pointer */
@@ -37,7 +35,6 @@ struct thread_info {
#define INIT_THREAD_INFO(tsk) \
{ \
.task = &tsk, \
- .addr_limit = KERNEL_DS, \
.preempt_count = INIT_PREEMPT_COUNT, \
}

diff --git a/arch/m68k/include/asm/tlbflush.h b/arch/m68k/include/asm/tlbflush.h
index a6318ccd308f..b882e2f4f551 100644
--- a/arch/m68k/include/asm/tlbflush.h
+++ b/arch/m68k/include/asm/tlbflush.h
@@ -13,13 +13,12 @@ static inline void flush_tlb_kernel_page(void *addr)
if (CPU_IS_COLDFIRE) {
mmu_write(MMUOR, MMUOR_CNL);
} else if (CPU_IS_040_OR_060) {
- mm_segment_t old_fs = get_fs();
- set_fs(KERNEL_DS);
+ set_fc(SUPER_DATA);
__asm__ __volatile__(".chip 68040\n\t"
"pflush (%0)\n\t"
".chip 68k"
: : "a" (addr));
- set_fs(old_fs);
+ set_fc(USER_DATA);
} else if (CPU_IS_020_OR_030)
__asm__ __volatile__("pflush #4,#4,(%0)" : : "a" (addr));
}
@@ -84,12 +83,8 @@ static inline void flush_tlb_mm(struct mm_struct *mm)

static inline void flush_tlb_page(struct vm_area_struct *vma, unsigned long addr)
{
- if (vma->vm_mm == current->active_mm) {
- mm_segment_t old_fs = force_uaccess_begin();
-
+ if (vma->vm_mm == current->active_mm)
__flush_tlb_one(addr);
- force_uaccess_end(old_fs);
- }
}

static inline void flush_tlb_range(struct vm_area_struct *vma,
diff --git a/arch/m68k/include/asm/uaccess.h b/arch/m68k/include/asm/uaccess.h
index 2bedb1b8c4bf..a308f0b41154 100644
--- a/arch/m68k/include/asm/uaccess.h
+++ b/arch/m68k/include/asm/uaccess.h
@@ -9,7 +9,6 @@
*/
#include <linux/compiler.h>
#include <linux/types.h>
-#include <asm/segment.h>
#include <asm/extable.h>

/* We let the MMU do all checking */
@@ -249,9 +248,6 @@ unsigned long raw_copy_from_user(void *to, const void __user *from,
unsigned long raw_copy_to_user(void __user *to, const void *from,
unsigned long n);

-#define user_addr_max() \
- (uaccess_kernel() ? ~0UL : TASK_SIZE)
-
extern long strncpy_from_user(char *dst, const char __user *src, long count);
extern __must_check long strnlen_user(const char __user *str, long n);

diff --git a/arch/m68k/kernel/asm-offsets.c b/arch/m68k/kernel/asm-offsets.c
index ccea355052ef..906d73230537 100644
--- a/arch/m68k/kernel/asm-offsets.c
+++ b/arch/m68k/kernel/asm-offsets.c
@@ -31,7 +31,7 @@ int main(void)
DEFINE(THREAD_KSP, offsetof(struct thread_struct, ksp));
DEFINE(THREAD_USP, offsetof(struct thread_struct, usp));
DEFINE(THREAD_SR, offsetof(struct thread_struct, sr));
- DEFINE(THREAD_FS, offsetof(struct thread_struct, fs));
+ DEFINE(THREAD_FC, offsetof(struct thread_struct, fc));
DEFINE(THREAD_CRP, offsetof(struct thread_struct, crp));
DEFINE(THREAD_ESP0, offsetof(struct thread_struct, esp0));
DEFINE(THREAD_FPREG, offsetof(struct thread_struct, fp));
diff --git a/arch/m68k/kernel/entry.S b/arch/m68k/kernel/entry.S
index 9dd76fbb7c6b..63434f331561 100644
--- a/arch/m68k/kernel/entry.S
+++ b/arch/m68k/kernel/entry.S
@@ -36,7 +36,6 @@
#include <linux/linkage.h>
#include <asm/errno.h>
#include <asm/setup.h>
-#include <asm/segment.h>
#include <asm/traps.h>
#include <asm/unistd.h>
#include <asm/asm-offsets.h>
@@ -338,7 +337,7 @@ resume:

/* save fs (sfc,%dfc) (may be pointing to kernel memory) */
movec %sfc,%d0
- movew %d0,%a0@(TASK_THREAD+THREAD_FS)
+ movew %d0,%a0@(TASK_THREAD+THREAD_FC)

/* save usp */
/* it is better to use a movel here instead of a movew 8*) */
@@ -424,7 +423,7 @@ resume:
movel %a0,%usp

/* restore fs (sfc,%dfc) */
- movew %a1@(TASK_THREAD+THREAD_FS),%a0
+ movew %a1@(TASK_THREAD+THREAD_FC),%a0
movec %a0,%sfc
movec %a0,%dfc

diff --git a/arch/m68k/kernel/process.c b/arch/m68k/kernel/process.c
index db49f9091711..1ab692b952cd 100644
--- a/arch/m68k/kernel/process.c
+++ b/arch/m68k/kernel/process.c
@@ -92,7 +92,7 @@ void show_regs(struct pt_regs * regs)

void flush_thread(void)
{
- current->thread.fs = __USER_DS;
+ current->thread.fc = USER_DATA;
#ifdef CONFIG_FPU
if (!FPU_IS_EMU) {
unsigned long zero = 0;
@@ -155,7 +155,7 @@ int copy_thread(unsigned long clone_flags, unsigned long usp, unsigned long arg,
* Must save the current SFC/DFC value, NOT the value when
* the parent was last descheduled - RGH 10-08-96
*/
- p->thread.fs = get_fs().seg;
+ p->thread.fc = USER_DATA;

if (unlikely(p->flags & (PF_KTHREAD | PF_IO_WORKER))) {
/* kernel thread */
diff --git a/arch/m68k/kernel/traps.c b/arch/m68k/kernel/traps.c
index 9e1261462bcc..c5e0a4f93bd5 100644
--- a/arch/m68k/kernel/traps.c
+++ b/arch/m68k/kernel/traps.c
@@ -181,9 +181,8 @@ static inline void access_error060 (struct frame *fp)
static inline unsigned long probe040(int iswrite, unsigned long addr, int wbs)
{
unsigned long mmusr;
- mm_segment_t old_fs = get_fs();

- set_fs(MAKE_MM_SEG(wbs));
+ set_fc(wbs);

if (iswrite)
asm volatile (".chip 68040; ptestw (%0); .chip 68k" : : "a" (addr));
@@ -192,7 +191,7 @@ static inline unsigned long probe040(int iswrite, unsigned long addr, int wbs)

asm volatile (".chip 68040; movec %%mmusr,%0; .chip 68k" : "=r" (mmusr));

- set_fs(old_fs);
+ set_fc(USER_DATA);

return mmusr;
}
@@ -201,10 +200,8 @@ static inline int do_040writeback1(unsigned short wbs, unsigned long wba,
unsigned long wbd)
{
int res = 0;
- mm_segment_t old_fs = get_fs();

- /* set_fs can not be moved, otherwise put_user() may oops */
- set_fs(MAKE_MM_SEG(wbs));
+ set_fc(wbs);

switch (wbs & WBSIZ_040) {
case BA_SIZE_BYTE:
@@ -218,9 +215,7 @@ static inline int do_040writeback1(unsigned short wbs, unsigned long wba,
break;
}

- /* set_fs can not be moved, otherwise put_user() may oops */
- set_fs(old_fs);
-
+ set_fc(USER_DATA);

pr_debug("do_040writeback1, res=%d\n", res);

diff --git a/arch/m68k/mac/misc.c b/arch/m68k/mac/misc.c
index 90f4e9ca1276..4fab34791758 100644
--- a/arch/m68k/mac/misc.c
+++ b/arch/m68k/mac/misc.c
@@ -18,7 +18,6 @@

#include <linux/uaccess.h>
#include <asm/io.h>
-#include <asm/segment.h>
#include <asm/setup.h>
#include <asm/macintosh.h>
#include <asm/mac_via.h>
diff --git a/arch/m68k/mm/cache.c b/arch/m68k/mm/cache.c
index b486c0889eec..d26eb1a591d3 100644
--- a/arch/m68k/mm/cache.c
+++ b/arch/m68k/mm/cache.c
@@ -12,7 +12,8 @@
#include <asm/traps.h>

-static unsigned long virt_to_phys_slow(unsigned long vaddr)
+static unsigned long virt_to_phys_slow(unsigned long vaddr,
+ unsigned long seg)
{
if (CPU_IS_060) {
unsigned long paddr;
@@ -55,7 +56,7 @@ static unsigned long virt_to_phys_slow(unsigned long vaddr)
asm volatile ("ptestr %3,%2@,#7,%0\n\t"
"pmove %%psr,%1"
: "=a&" (descaddr), "=m" (mmusr)
- : "a" (vaddr), "d" (get_fs().seg));
+ : "a" (vaddr), "d" (seg));
if (mmusr & (MMU_I|MMU_B|MMU_L))
return 0;
descaddr = phys_to_virt((unsigned long)descaddr);
@@ -73,7 +74,8 @@ static unsigned long virt_to_phys_slow(unsigned long vaddr)

/* Push n pages at kernel virtual address and clear the icache */
/* RZ: use cpush %bc instead of cpush %dc, cinv %ic */
-void flush_icache_user_range(unsigned long address, unsigned long endaddr)
+static void __flush_icache_range(unsigned long address, unsigned long endaddr,
+ unsigned long seg)
{
if (CPU_IS_COLDFIRE) {
unsigned long start, end;
@@ -92,7 +94,7 @@ void flush_icache_user_range(unsigned long address, unsigned long endaddr)
".chip 68040\n\t"
"cpushp %%bc,(%0)\n\t"
".chip 68k"
- : : "a" (virt_to_phys_slow(address)));
+ : : "a" (virt_to_phys_slow(address, seg)));
address += PAGE_SIZE;
} while (address < endaddr);
} else {
@@ -105,13 +107,16 @@ void flush_icache_user_range(unsigned long address, unsigned long endaddr)
}
}

-void flush_icache_range(unsigned long address, unsigned long endaddr)
+void flush_icache_user_range(unsigned long address, unsigned long endaddr)
{
- mm_segment_t old_fs = get_fs();
+ __flush_icache_range(address, endaddr, USER_DATA);
+}

- set_fs(KERNEL_DS);
- flush_icache_user_range(address, endaddr);
- set_fs(old_fs);
+void flush_icache_range(unsigned long address, unsigned long endaddr)
+{
+ set_fc(SUPER_DATA);
+ __flush_icache_range(address, endaddr, SUPER_DATA);
+ set_fc(USER_DATA);
}
EXPORT_SYMBOL(flush_icache_range);

diff --git a/arch/m68k/mm/init.c b/arch/m68k/mm/init.c
index 5d749e188246..133cd8802a78 100644
--- a/arch/m68k/mm/init.c
+++ b/arch/m68k/mm/init.c
@@ -76,7 +76,7 @@ void __init paging_init(void)
/*
* Set up SFC/DFC registers (user data space).
*/
- set_fs (USER_DS);
+ set_fc(USER_DATA);

max_zone_pfn[ZONE_DMA] = end_mem >> PAGE_SHIFT;
free_area_init(max_zone_pfn);
diff --git a/arch/m68k/mm/kmap.c b/arch/m68k/mm/kmap.c
index 1269d513b221..20ddf71b43d0 100644
--- a/arch/m68k/mm/kmap.c
+++ b/arch/m68k/mm/kmap.c
@@ -17,7 +17,6 @@
#include <linux/vmalloc.h>

#include <asm/setup.h>
-#include <asm/segment.h>
#include <asm/page.h>
#include <asm/io.h>
#include <asm/tlbflush.h>
diff --git a/arch/m68k/mm/memory.c b/arch/m68k/mm/memory.c
index fe75aecfb238..c2c03b0a1567 100644
--- a/arch/m68k/mm/memory.c
+++ b/arch/m68k/mm/memory.c
@@ -15,7 +15,6 @@
#include <linux/gfp.h>

#include <asm/setup.h>
-#include <asm/segment.h>
#include <asm/page.h>
#include <asm/traps.h>
#include <asm/machdep.h>
diff --git a/arch/m68k/mm/motorola.c b/arch/m68k/mm/motorola.c
index 3a653f0a4188..9f3f77785aa7 100644
--- a/arch/m68k/mm/motorola.c
+++ b/arch/m68k/mm/motorola.c
@@ -467,7 +467,7 @@ void __init paging_init(void)
/*
* Set up SFC/DFC registers
*/
- set_fs(KERNEL_DS);
+ set_fc(USER_DATA);

#ifdef DEBUG
printk ("before free_area_init\n");
diff --git a/arch/m68k/sun3/config.c b/arch/m68k/sun3/config.c
index f7dd47232b6c..203f428a0344 100644
--- a/arch/m68k/sun3/config.c
+++ b/arch/m68k/sun3/config.c
@@ -31,7 +31,6 @@
#include <asm/intersil.h>
#include <asm/irq.h>
#include <asm/sections.h>
-#include <asm/segment.h>
#include <asm/sun3ints.h>

char sun3_reserved_pmeg[SUN3_PMEGS_NUM];
@@ -89,7 +88,7 @@ void __init sun3_init(void)
sun3_reserved_pmeg[249] = 1;
sun3_reserved_pmeg[252] = 1;
sun3_reserved_pmeg[253] = 1;
- set_fs(KERNEL_DS);
+ set_fc(USER_DATA);
}

/* Without this, Bad Things happen when something calls arch_reset. */
diff --git a/arch/m68k/sun3/mmu_emu.c b/arch/m68k/sun3/mmu_emu.c
index 7aa879b7c7ff..7ec20817c0c9 100644
--- a/arch/m68k/sun3/mmu_emu.c
+++ b/arch/m68k/sun3/mmu_emu.c
@@ -23,7 +23,6 @@
#include <linux/uaccess.h>
#include <asm/page.h>
#include <asm/sun3mmu.h>
-#include <asm/segment.h>
#include <asm/oplib.h>
#include <asm/mmu_context.h>
#include <asm/dvma.h>
@@ -191,14 +190,13 @@ void __init mmu_emu_init(unsigned long bootmem_end)
for(seg = 0; seg < PAGE_OFFSET; seg += SUN3_PMEG_SIZE)
sun3_put_segmap(seg, SUN3_INVALID_PMEG);

- set_fs(MAKE_MM_SEG(3));
+ set_fc(3);
for(seg = 0; seg < 0x10000000; seg += SUN3_PMEG_SIZE) {
i = sun3_get_segmap(seg);
for(j = 1; j < CONTEXTS_NUM; j++)
(*(romvec->pv_setctxt))(j, (void *)seg, i);
}
- set_fs(KERNEL_DS);
-
+ set_fc(USER_DATA);
}

/* erase the mappings for a dead context. Uses the pg_dir for hints
diff --git a/arch/m68k/sun3/sun3ints.c b/arch/m68k/sun3/sun3ints.c
index 41ae422119d3..36cc280a4505 100644
--- a/arch/m68k/sun3/sun3ints.c
+++ b/arch/m68k/sun3/sun3ints.c
@@ -11,7 +11,6 @@
#include <linux/sched.h>
#include <linux/kernel_stat.h>
#include <linux/interrupt.h>
-#include <asm/segment.h>
#include <asm/intersil.h>
#include <asm/oplib.h>
#include <asm/sun3ints.h>
diff --git a/arch/m68k/sun3x/prom.c b/arch/m68k/sun3x/prom.c
index 74d2fe57524b..64c23bfaa90c 100644
--- a/arch/m68k/sun3x/prom.c
+++ b/arch/m68k/sun3x/prom.c
@@ -14,7 +14,6 @@
#include <asm/traps.h>
#include <asm/sun3xprom.h>
#include <asm/idprom.h>
-#include <asm/segment.h>
#include <asm/sun3ints.h>
#include <asm/openprom.h>
#include <asm/machines.h>
--
2.30.2