[PATCH 5/10] m68k: convert thread flags to use bit fields

From: Roman Zippel
Date: Thu Sep 01 2005 - 17:00:59 EST


Remove task_work structure, use the standard thread flags functions and
use shifts in entry.S to test the thread flags. Add a few local labels
to entry.S to allow gas to generate short jumps.
Finally it changes a number of inline functions in thread_info.h to macros
to delay the current_thread_info() usage, which requires on m68k a structure
(task_struct) not yet defined at this point.

Signed-off-by: Roman Zippel <zippel@xxxxxxxxxxxxxx>

---

arch/m68k/fpsp040/skeleton.S | 6 +--
arch/m68k/ifpsp060/iskeleton.S | 6 +--
arch/m68k/kernel/asm-offsets.c | 5 --
arch/m68k/kernel/entry.S | 78 ++++++++++++++++++++-------------------
arch/m68k/kernel/ptrace.c | 15 +++----
include/asm-m68k/processor.h | 12 ------
include/asm-m68k/thread_info.h | 81 ++++-------------------------------------
include/linux/thread_info.h | 45 ++++++----------------
8 files changed, 71 insertions(+), 177 deletions(-)

Index: linux-2.6-mm/arch/m68k/fpsp040/skeleton.S
===================================================================
--- linux-2.6-mm.orig/arch/m68k/fpsp040/skeleton.S 2005-09-01 13:21:50.000000000 +0200
+++ linux-2.6-mm/arch/m68k/fpsp040/skeleton.S 2005-09-01 21:04:39.636108908 +0200
@@ -381,10 +381,8 @@ fpsp_done:
.Lnotkern:
SAVE_ALL_INT
GET_CURRENT(%d0)
- tstb %curptr@(TASK_NEEDRESCHED)
- jne ret_from_exception | deliver signals,
- | reschedule etc..
- RESTORE_ALL
+ | deliver signals, reschedule etc..
+ jra ret_from_exception

|
| mem_write --- write to user or supervisor address space
Index: linux-2.6-mm/arch/m68k/ifpsp060/iskeleton.S
===================================================================
--- linux-2.6-mm.orig/arch/m68k/ifpsp060/iskeleton.S 2005-09-01 13:21:50.000000000 +0200
+++ linux-2.6-mm/arch/m68k/ifpsp060/iskeleton.S 2005-09-01 21:04:39.676102037 +0200
@@ -75,10 +75,8 @@ _060_isp_done:
.Lnotkern:
SAVE_ALL_INT
GET_CURRENT(%d0)
- tstb %curptr@(TASK_NEEDRESCHED)
- jne ret_from_exception | deliver signals,
- | reschedule etc..
- RESTORE_ALL
+ | deliver signals, reschedule etc..
+ jra ret_from_exception

|
| _060_real_chk():
Index: linux-2.6-mm/arch/m68k/kernel/asm-offsets.c
===================================================================
--- linux-2.6-mm.orig/arch/m68k/kernel/asm-offsets.c 2005-09-01 21:04:36.173703799 +0200
+++ linux-2.6-mm/arch/m68k/kernel/asm-offsets.c 2005-09-01 21:04:39.676102037 +0200
@@ -25,11 +25,6 @@ int main(void)
DEFINE(TASK_STATE, offsetof(struct task_struct, state));
DEFINE(TASK_FLAGS, offsetof(struct task_struct, flags));
DEFINE(TASK_PTRACE, offsetof(struct task_struct, ptrace));
- DEFINE(TASK_WORK, offsetof(struct task_struct, thread.work));
- DEFINE(TASK_NEEDRESCHED, offsetof(struct task_struct, thread.work.need_resched));
- DEFINE(TASK_SYSCALL_TRACE, offsetof(struct task_struct, thread.work.syscall_trace));
- DEFINE(TASK_SIGPENDING, offsetof(struct task_struct, thread.work.sigpending));
- DEFINE(TASK_NOTIFY_RESUME, offsetof(struct task_struct, thread.work.notify_resume));
DEFINE(TASK_THREAD, offsetof(struct task_struct, thread));
DEFINE(TASK_INFO, offsetof(struct task_struct, thread.info));
DEFINE(TASK_MM, offsetof(struct task_struct, mm));
Index: linux-2.6-mm/arch/m68k/kernel/entry.S
===================================================================
--- linux-2.6-mm.orig/arch/m68k/kernel/entry.S 2005-09-01 13:21:50.000000000 +0200
+++ linux-2.6-mm/arch/m68k/kernel/entry.S 2005-09-01 21:04:39.695098773 +0200
@@ -44,9 +44,7 @@

#include <asm/offsets.h>

-.globl system_call, buserr, trap
-.globl resume, ret_from_exception
-.globl ret_from_signal
+.globl system_call, buserr, trap, resume
.globl inthandler, sys_call_table
.globl sys_fork, sys_clone, sys_vfork
.globl ret_from_interrupt, bad_interrupt
@@ -58,7 +56,7 @@ ENTRY(buserr)
movel %sp,%sp@- | stack frame pointer argument
bsrl buserr_c
addql #4,%sp
- jra ret_from_exception
+ jra .Lret_from_exception

ENTRY(trap)
SAVE_ALL_INT
@@ -66,7 +64,7 @@ ENTRY(trap)
movel %sp,%sp@- | stack frame pointer argument
bsrl trap_c
addql #4,%sp
- jra ret_from_exception
+ jra .Lret_from_exception

| After a fork we jump here directly from resume,
| so that %d1 contains the previous task
@@ -75,30 +73,31 @@ ENTRY(ret_from_fork)
movel %d1,%sp@-
jsr schedule_tail
addql #4,%sp
- jra ret_from_exception
+ jra .Lret_from_exception

-badsys:
- movel #-ENOSYS,%sp@(PT_D0)
- jra ret_from_exception
-
-do_trace:
+do_trace_entry:
movel #-ENOSYS,%sp@(PT_D0) | needed for strace
subql #4,%sp
SAVE_SWITCH_STACK
jbsr syscall_trace
RESTORE_SWITCH_STACK
addql #4,%sp
- movel %sp@(PT_ORIG_D0),%d1
- movel #-ENOSYS,%d0
- cmpl #NR_syscalls,%d1
- jcc 1f
- jbsr @(sys_call_table,%d1:l:4)@(0)
-1: movel %d0,%sp@(PT_D0) | save the return value
- subql #4,%sp | dummy return address
+ movel %sp@(PT_ORIG_D0),%d0
+ cmpl #NR_syscalls,%d0
+ jcs syscall
+badsys:
+ movel #-ENOSYS,%sp@(PT_D0)
+ jra ret_from_syscall
+
+do_trace_exit:
+ subql #4,%sp
SAVE_SWITCH_STACK
jbsr syscall_trace
+ RESTORE_SWITCH_STACK
+ addql #4,%sp
+ jra .Lret_from_exception

-ret_from_signal:
+ENTRY(ret_from_signal)
RESTORE_SWITCH_STACK
addql #4,%sp
/* on 68040 complete pending writebacks if any */
@@ -111,7 +110,7 @@ ret_from_signal:
addql #4,%sp
1:
#endif
- jra ret_from_exception
+ jra .Lret_from_exception

ENTRY(system_call)
SAVE_ALL_SYS
@@ -120,30 +119,34 @@ ENTRY(system_call)
| save top of frame
movel %sp,%curptr@(TASK_THREAD+THREAD_ESP0)

- tstb %curptr@(TASK_SYSCALL_TRACE)
- jne do_trace
+ | syscall trace?
+ tstb %curptr@(TASK_INFO+TINFO_FLAGS+2)
+ jmi do_trace_entry
cmpl #NR_syscalls,%d0
jcc badsys
+syscall:
jbsr @(sys_call_table,%d0:l:4)@(0)
movel %d0,%sp@(PT_D0) | save the return value
-
+ret_from_syscall:
|oriw #0x0700,%sr
- movel %curptr@(TASK_WORK),%d0
+ movew %curptr@(TASK_INFO+TINFO_FLAGS+2),%d0
jne syscall_exit_work
1: RESTORE_ALL

syscall_exit_work:
btst #5,%sp@(PT_SR) | check if returning to kernel
bnes 1b | if so, skip resched, signals
- tstw %d0
- jeq do_signal_return
- tstb %d0
- jne do_delayed_trace
-
+ lslw #1,%d0
+ jcs do_trace_exit
+ jmi do_delayed_trace
+ lslw #8,%d0
+ jmi do_signal_return
pea resume_userspace
- jmp schedule
+ jra schedule
+

-ret_from_exception:
+ENTRY(ret_from_exception)
+.Lret_from_exception:
btst #5,%sp@(PT_SR) | check if returning to kernel
bnes 1f | if so, skip resched, signals
| only allow interrupts when we are really the last one on the
@@ -152,19 +155,18 @@ ret_from_exception:
andw #ALLOWINT,%sr

resume_userspace:
- movel %curptr@(TASK_WORK),%d0
- lsrl #8,%d0
+ moveb %curptr@(TASK_INFO+TINFO_FLAGS+3),%d0
jne exit_work
1: RESTORE_ALL

exit_work:
| save top of frame
movel %sp,%curptr@(TASK_THREAD+THREAD_ESP0)
- tstb %d0
- jeq do_signal_return
-
+ lslb #1,%d0
+ jmi do_signal_return
pea resume_userspace
- jmp schedule
+ jra schedule
+

do_signal_return:
|andw #ALLOWINT,%sr
@@ -254,7 +256,7 @@ ret_from_interrupt:

/* check if we need to do software interrupts */
tstl irq_stat+CPUSTAT_SOFTIRQ_PENDING
- jeq ret_from_exception
+ jeq .Lret_from_exception
pea ret_from_exception
jra do_softirq

Index: linux-2.6-mm/arch/m68k/kernel/ptrace.c
===================================================================
--- linux-2.6-mm.orig/arch/m68k/kernel/ptrace.c 2005-09-01 21:04:00.912762727 +0200
+++ linux-2.6-mm/arch/m68k/kernel/ptrace.c 2005-09-01 21:04:39.696098601 +0200
@@ -109,7 +109,7 @@ static inline void singlestep_disable(st
{
unsigned long tmp = get_reg(child, PT_SR) & ~(TRACE_BITS << 16);
put_reg(child, PT_SR, tmp);
- child->thread.work.delayed_trace = 0;
+ clear_tsk_thread_flag(child, TIF_DELAYED_TRACE);
}

/*
@@ -118,7 +118,7 @@ static inline void singlestep_disable(st
void ptrace_disable(struct task_struct *child)
{
singlestep_disable(child);
- child->thread.work.syscall_trace = 0;
+ clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
}

asmlinkage int sys_ptrace(long request, long pid, long addr, long data)
@@ -235,9 +235,9 @@ asmlinkage int sys_ptrace(long request,
goto out_eio;

if (request == PTRACE_SYSCALL)
- child->thread.work.syscall_trace = ~0;
+ set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
else
- child->thread.work.syscall_trace = 0;
+ clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
child->exit_code = data;
singlestep_disable(child);
wake_up_process(child);
@@ -260,10 +260,10 @@ asmlinkage int sys_ptrace(long request,
if (!valid_signal(data))
goto out_eio;

- child->thread.work.syscall_trace = 0;
+ clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
tmp = get_reg(child, PT_SR) | (TRACE_BITS << 16);
put_reg(child, PT_SR, tmp);
- child->thread.work.delayed_trace = 1;
+ set_tsk_thread_flag(child, TIF_DELAYED_TRACE);

child->exit_code = data;
/* give it a chance to run. */
@@ -329,9 +329,6 @@ out_eio:

asmlinkage void syscall_trace(void)
{
- if (!current->thread.work.delayed_trace &&
- !current->thread.work.syscall_trace)
- return;
ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
? 0x80 : 0));
/*
Index: linux-2.6-mm/include/asm-m68k/processor.h
===================================================================
--- linux-2.6-mm.orig/include/asm-m68k/processor.h 2005-09-01 21:04:36.184701909 +0200
+++ linux-2.6-mm/include/asm-m68k/processor.h 2005-09-01 21:04:39.696098601 +0200
@@ -56,17 +56,6 @@ static inline void wrusp(unsigned long u
#endif
#define TASK_UNMAPPED_ALIGN(addr, off) PAGE_ALIGN(addr)

-struct task_work {
- unsigned char sigpending;
- unsigned char notify_resume; /* request for notification on
- userspace execution resumption */
- char need_resched;
- unsigned char delayed_trace; /* single step a syscall */
- unsigned char syscall_trace; /* count of syscall interceptors */
- unsigned char memdie; /* task was selected to be killed */
- unsigned char pad[2];
-};
-
struct thread_struct {
unsigned long ksp; /* kernel stack pointer */
unsigned long usp; /* user stack pointer */
@@ -79,7 +68,6 @@ struct thread_struct {
unsigned long fp[8*3];
unsigned long fpcntl[3]; /* fp control regs */
unsigned char fpstate[FPSTATESIZE]; /* floating point state */
- struct task_work work;
struct thread_info info;
};

Index: linux-2.6-mm/include/asm-m68k/thread_info.h
===================================================================
--- linux-2.6-mm.orig/include/asm-m68k/thread_info.h 2005-09-01 21:04:36.216696412 +0200
+++ linux-2.6-mm/include/asm-m68k/thread_info.h 2005-09-01 21:04:39.711096024 +0200
@@ -6,12 +6,11 @@

struct thread_info {
struct task_struct *task; /* main task structure */
+ unsigned long flags;
struct exec_domain *exec_domain; /* execution domain */
int preempt_count; /* 0 => preemptable, <0 => BUG */
__u32 cpu; /* should always be 0 on m68k */
struct restart_block restart_block;
-
- __u8 supervisor_stack[0];
};

#define PREEMPT_ACTIVE 0x4000000
@@ -49,76 +48,14 @@ struct thread_info {

#define end_of_stack(p) ((unsigned long *)(p)->thread_info + 1)

-#define TIF_SYSCALL_TRACE 0 /* syscall trace active */
-#define TIF_DELAYED_TRACE 1 /* single step a syscall */
-#define TIF_NOTIFY_RESUME 2 /* resumption notification requested */
-#define TIF_SIGPENDING 3 /* signal pending */
-#define TIF_NEED_RESCHED 4 /* rescheduling necessary */
-#define TIF_MEMDIE 5
-
-extern int thread_flag_fixme(void);
-
-/*
- * flag set/clear/test wrappers
- * - pass TIF_xxxx constants to these functions
+/* entry.S relies on these definitions!
+ * bits 0-7 are tested at every exception exit
+ * bits 8-15 are also tested at syscall exit
*/
-
-#define __set_tsk_thread_flag(tsk, flag, val) ({ \
- switch (flag) { \
- case TIF_SIGPENDING: \
- tsk->thread.work.sigpending = val; \
- break; \
- case TIF_NEED_RESCHED: \
- tsk->thread.work.need_resched = val; \
- break; \
- case TIF_SYSCALL_TRACE: \
- tsk->thread.work.syscall_trace = val; \
- break; \
- case TIF_MEMDIE: \
- tsk->thread.work.memdie = val; \
- break; \
- default: \
- thread_flag_fixme(); \
- } \
-})
-
-#define __get_tsk_thread_flag(tsk, flag) ({ \
- int ___res; \
- switch (flag) { \
- case TIF_SIGPENDING: \
- ___res = tsk->thread.work.sigpending; \
- break; \
- case TIF_NEED_RESCHED: \
- ___res = tsk->thread.work.need_resched; \
- break; \
- case TIF_SYSCALL_TRACE: \
- ___res = tsk->thread.work.syscall_trace;\
- break; \
- case TIF_MEMDIE: \
- ___res = tsk->thread.work.memdie;\
- break; \
- default: \
- ___res = thread_flag_fixme(); \
- } \
- ___res; \
-})
-
-#define __get_set_tsk_thread_flag(tsk, flag, val) ({ \
- int __res = __get_tsk_thread_flag(tsk, flag); \
- __set_tsk_thread_flag(tsk, flag, val); \
- __res; \
-})
-
-#define set_tsk_thread_flag(tsk, flag) __set_tsk_thread_flag(tsk, flag, ~0)
-#define clear_tsk_thread_flag(tsk, flag) __set_tsk_thread_flag(tsk, flag, 0)
-#define test_and_set_tsk_thread_flag(tsk, flag) __get_set_tsk_thread_flag(tsk, flag, ~0)
-#define test_tsk_thread_flag(tsk, flag) __get_tsk_thread_flag(tsk, flag)
-
-#define set_thread_flag(flag) set_tsk_thread_flag(current, flag)
-#define clear_thread_flag(flag) clear_tsk_thread_flag(current, flag)
-#define test_thread_flag(flag) test_tsk_thread_flag(current, flag)
-
-#define set_need_resched() set_thread_flag(TIF_NEED_RESCHED)
-#define clear_need_resched() clear_thread_flag(TIF_NEED_RESCHED)
+#define TIF_SIGPENDING 6 /* signal pending */
+#define TIF_NEED_RESCHED 7 /* rescheduling necessary */
+#define TIF_DELAYED_TRACE 14 /* single step a syscall */
+#define TIF_SYSCALL_TRACE 15 /* syscall trace active */
+#define TIF_MEMDIE 16

#endif /* _ASM_M68K_THREAD_INFO_H */
Index: linux-2.6-mm/include/linux/thread_info.h
===================================================================
--- linux-2.6-mm.orig/include/linux/thread_info.h 2005-09-01 13:21:50.000000000 +0200
+++ linux-2.6-mm/include/linux/thread_info.h 2005-09-01 21:04:39.711096024 +0200
@@ -27,31 +27,6 @@ extern long do_no_restart_syscall(struct
* - pass TIF_xxxx constants to these functions
*/

-static inline void set_thread_flag(int flag)
-{
- set_bit(flag,&current_thread_info()->flags);
-}
-
-static inline void clear_thread_flag(int flag)
-{
- clear_bit(flag,&current_thread_info()->flags);
-}
-
-static inline int test_and_set_thread_flag(int flag)
-{
- return test_and_set_bit(flag,&current_thread_info()->flags);
-}
-
-static inline int test_and_clear_thread_flag(int flag)
-{
- return test_and_clear_bit(flag,&current_thread_info()->flags);
-}
-
-static inline int test_thread_flag(int flag)
-{
- return test_bit(flag,&current_thread_info()->flags);
-}
-
static inline void set_ti_thread_flag(struct thread_info *ti, int flag)
{
set_bit(flag,&ti->flags);
@@ -77,15 +52,19 @@ static inline int test_ti_thread_flag(st
return test_bit(flag,&ti->flags);
}

-static inline void set_need_resched(void)
-{
- set_thread_flag(TIF_NEED_RESCHED);
-}
+#define set_thread_flag(flag) \
+ set_ti_thread_flag(current_thread_info(), flag)
+#define clear_thread_flag(flag) \
+ clear_ti_thread_flag(current_thread_info(), flag)
+#define test_and_set_thread_flag(flag) \
+ test_and_set_ti_thread_flag(current_thread_info(), flag)
+#define test_and_clear_thread_flag(flag) \
+ test_and_clear_ti_thread_flag(current_thread_info(), flag)
+#define test_thread_flag(flag) \
+ test_ti_thread_flag(current_thread_info(), flag)

-static inline void clear_need_resched(void)
-{
- clear_thread_flag(TIF_NEED_RESCHED);
-}
+#define set_need_resched() set_thread_flag(TIF_NEED_RESCHED)
+#define clear_need_resched() clear_thread_flag(TIF_NEED_RESCHED)

#endif

-
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