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authorDavid Woodhouse <dwmw2@infradead.org>2005-11-15 18:52:18 +0000
committerPaul Mackerras <paulus@samba.org>2006-01-09 14:49:01 +1100
commit401d1f029bebb7153ca704997772113dc36d9527 (patch)
tree01a3d649ac591d7a1fb910ce29a7223ffb629f9a /arch/powerpc/kernel/entry_32.S
parent1cd8e506209223ed10da805d99be55e268f4023c (diff)
[PATCH] syscall entry/exit revamp
This cleanup patch speeds up the null syscall path on ppc64 by about 3%, and brings the ppc32 and ppc64 code slightly closer together. The ppc64 code was checking current_thread_info()->flags twice in the syscall exit path; once for TIF_SYSCALL_T_OR_A before disabling interrupts, and then again for TIF_SIGPENDING|TIF_NEED_RESCHED etc after disabling interrupts. Now we do the same as ppc32 -- check the flags only once in the fast path, and re-enable interrupts if necessary in the ptrace case. The patch abolishes the 'syscall_noerror' member of struct thread_info and replaces it with a TIF_NOERROR bit in the flags, which is handled in the slow path. This shortens the syscall entry code, which no longer needs to clear syscall_noerror. The patch adds a TIF_SAVE_NVGPRS flag which causes the syscall exit slow path to save the non-volatile GPRs into a signal frame. This removes the need for the assembly wrappers around sys_sigsuspend(), sys_rt_sigsuspend(), et al which existed solely to save those registers in advance. It also means I don't have to add new wrappers for ppoll() and pselect(), which is what I was supposed to be doing when I got distracted into this... Finally, it unifies the ppc64 and ppc32 methods of handling syscall exit directly into a signal handler (as required by sigsuspend et al) by introducing a TIF_RESTOREALL flag which causes _all_ the registers to be reloaded from the pt_regs by taking the ret_from_exception path, instead of the normal syscall exit path which stomps on the callee-saved GPRs. It appears to pass an LTP test run on ppc64, and passes basic testing on ppc32 too. Brief tests of ptrace functionality with strace and gdb also appear OK. I wouldn't send it to Linus for 2.6.15 just yet though :) Signed-off-by: David Woodhouse <dwmw2@infradead.org> Signed-off-by: Paul Mackerras <paulus@samba.org>
Diffstat (limited to 'arch/powerpc/kernel/entry_32.S')
-rw-r--r--arch/powerpc/kernel/entry_32.S167
1 files changed, 96 insertions, 71 deletions
diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
index 2e99ae41723..8fed9538f18 100644
--- a/arch/powerpc/kernel/entry_32.S
+++ b/arch/powerpc/kernel/entry_32.S
@@ -200,8 +200,6 @@ _GLOBAL(DoSyscall)
bl do_show_syscall
#endif /* SHOW_SYSCALLS */
rlwinm r10,r1,0,0,(31-THREAD_SHIFT) /* current_thread_info() */
- li r11,0
- stb r11,TI_SC_NOERR(r10)
lwz r11,TI_FLAGS(r10)
andi. r11,r11,_TIF_SYSCALL_T_OR_A
bne- syscall_dotrace
@@ -222,25 +220,21 @@ ret_from_syscall:
bl do_show_syscall_exit
#endif
mr r6,r3
- li r11,-_LAST_ERRNO
- cmplw 0,r3,r11
rlwinm r12,r1,0,0,(31-THREAD_SHIFT) /* current_thread_info() */
- blt+ 30f
- lbz r11,TI_SC_NOERR(r12)
- cmpwi r11,0
- bne 30f
- neg r3,r3
- lwz r10,_CCR(r1) /* Set SO bit in CR */
- oris r10,r10,0x1000
- stw r10,_CCR(r1)
-
/* disable interrupts so current_thread_info()->flags can't change */
-30: LOAD_MSR_KERNEL(r10,MSR_KERNEL) /* doesn't include MSR_EE */
+ LOAD_MSR_KERNEL(r10,MSR_KERNEL) /* doesn't include MSR_EE */
SYNC
MTMSRD(r10)
lwz r9,TI_FLAGS(r12)
- andi. r0,r9,(_TIF_SYSCALL_T_OR_A|_TIF_SIGPENDING|_TIF_NEED_RESCHED)
+ li r8,-_LAST_ERRNO
+ andi. r0,r9,(_TIF_SYSCALL_T_OR_A|_TIF_SIGPENDING|_TIF_NEED_RESCHED|_TIF_RESTOREALL)
bne- syscall_exit_work
+ cmplw 0,r3,r8
+ blt+ syscall_exit_cont
+ lwz r11,_CCR(r1) /* Load CR */
+ neg r3,r3
+ oris r11,r11,0x1000 /* Set SO bit in CR */
+ stw r11,_CCR(r1)
syscall_exit_cont:
#if defined(CONFIG_4xx) || defined(CONFIG_BOOKE)
/* If the process has its own DBCR0 value, load it up. The single
@@ -292,46 +286,113 @@ syscall_dotrace:
b syscall_dotrace_cont
syscall_exit_work:
- stw r6,RESULT(r1) /* Save result */
+ andi. r0,r9,_TIF_RESTOREALL
+ bne- 2f
+ cmplw 0,r3,r8
+ blt+ 1f
+ andi. r0,r9,_TIF_NOERROR
+ bne- 1f
+ lwz r11,_CCR(r1) /* Load CR */
+ neg r3,r3
+ oris r11,r11,0x1000 /* Set SO bit in CR */
+ stw r11,_CCR(r1)
+
+1: stw r6,RESULT(r1) /* Save result */
stw r3,GPR3(r1) /* Update return value */
- andi. r0,r9,_TIF_SYSCALL_T_OR_A
- beq 5f
- ori r10,r10,MSR_EE
- SYNC
- MTMSRD(r10) /* re-enable interrupts */
+2: andi. r0,r9,(_TIF_PERSYSCALL_MASK)
+ beq 4f
+
+ /* Clear per-syscall TIF flags if any are set, but _leave_
+ _TIF_SAVE_NVGPRS set in r9 since we haven't dealt with that
+ yet. */
+
+ li r11,_TIF_PERSYSCALL_MASK
+ addi r12,r12,TI_FLAGS
+3: lwarx r8,0,r12
+ andc r8,r8,r11
+#ifdef CONFIG_IBM405_ERR77
+ dcbt 0,r12
+#endif
+ stwcx. r8,0,r12
+ bne- 3b
+ subi r12,r12,TI_FLAGS
+
+4: /* Anything which requires enabling interrupts? */
+ andi. r0,r9,(_TIF_SYSCALL_T_OR_A|_TIF_SINGLESTEP|_TIF_SAVE_NVGPRS)
+ beq 7f
+
+ /* Save NVGPRS if they're not saved already */
lwz r4,_TRAP(r1)
andi. r4,r4,1
- beq 4f
+ beq 5f
SAVE_NVGPRS(r1)
li r4,0xc00
stw r4,_TRAP(r1)
-4:
+
+ /* Re-enable interrupts */
+5: ori r10,r10,MSR_EE
+ SYNC
+ MTMSRD(r10)
+
+ andi. r0,r9,_TIF_SAVE_NVGPRS
+ bne save_user_nvgprs
+
+save_user_nvgprs_cont:
+ andi. r0,r9,(_TIF_SYSCALL_T_OR_A|_TIF_SINGLESTEP)
+ beq 7f
+
addi r3,r1,STACK_FRAME_OVERHEAD
bl do_syscall_trace_leave
REST_NVGPRS(r1)
-2:
- lwz r3,GPR3(r1)
+
+6: lwz r3,GPR3(r1)
LOAD_MSR_KERNEL(r10,MSR_KERNEL) /* doesn't include MSR_EE */
SYNC
MTMSRD(r10) /* disable interrupts again */
rlwinm r12,r1,0,0,(31-THREAD_SHIFT) /* current_thread_info() */
lwz r9,TI_FLAGS(r12)
-5:
+7:
andi. r0,r9,_TIF_NEED_RESCHED
- bne 1f
+ bne 8f
lwz r5,_MSR(r1)
andi. r5,r5,MSR_PR
- beq syscall_exit_cont
+ beq ret_from_except
andi. r0,r9,_TIF_SIGPENDING
- beq syscall_exit_cont
+ beq ret_from_except
b do_user_signal
-1:
+8:
ori r10,r10,MSR_EE
SYNC
MTMSRD(r10) /* re-enable interrupts */
bl schedule
- b 2b
+ b 6b
+
+save_user_nvgprs:
+ ld r8,TI_SIGFRAME(r12)
+
+.macro savewords start, end
+ 1: stw \start,4*(\start)(r8)
+ .section __ex_table,"a"
+ .align 2
+ .long 1b,save_user_nvgprs_fault
+ .previous
+ .if \end - \start
+ savewords "(\start+1)",\end
+ .endif
+.endm
+ savewords 14,31
+ b save_user_nvgprs_cont
+
+
+save_user_nvgprs_fault:
+ li r3,11 /* SIGSEGV */
+ ld r4,TI_TASK(r12)
+ bl force_sigsegv
+ rlwinm r12,r1,0,0,(31-THREAD_SHIFT) /* current_thread_info() */
+ ld r9,TI_FLAGS(r12)
+ b save_user_nvgprs_cont
+
#ifdef SHOW_SYSCALLS
do_show_syscall:
#ifdef SHOW_SYSCALLS_TASK
@@ -401,28 +462,10 @@ show_syscalls_task:
#endif /* SHOW_SYSCALLS */
/*
- * The sigsuspend and rt_sigsuspend system calls can call do_signal
- * and thus put the process into the stopped state where we might
- * want to examine its user state with ptrace. Therefore we need
- * to save all the nonvolatile registers (r13 - r31) before calling
- * the C code.
+ * The fork/clone functions need to copy the full register set into
+ * the child process. Therefore we need to save all the nonvolatile
+ * registers (r13 - r31) before calling the C code.
*/
- .globl ppc_sigsuspend
-ppc_sigsuspend:
- SAVE_NVGPRS(r1)
- lwz r0,_TRAP(r1)
- rlwinm r0,r0,0,0,30 /* clear LSB to indicate full */
- stw r0,_TRAP(r1) /* register set saved */
- b sys_sigsuspend
-
- .globl ppc_rt_sigsuspend
-ppc_rt_sigsuspend:
- SAVE_NVGPRS(r1)
- lwz r0,_TRAP(r1)
- rlwinm r0,r0,0,0,30
- stw r0,_TRAP(r1)
- b sys_rt_sigsuspend
-
.globl ppc_fork
ppc_fork:
SAVE_NVGPRS(r1)
@@ -447,14 +490,6 @@ ppc_clone:
stw r0,_TRAP(r1) /* register set saved */
b sys_clone
- .globl ppc_swapcontext
-ppc_swapcontext:
- SAVE_NVGPRS(r1)
- lwz r0,_TRAP(r1)
- rlwinm r0,r0,0,0,30 /* clear LSB to indicate full */
- stw r0,_TRAP(r1) /* register set saved */
- b sys_swapcontext
-
/*
* Top-level page fault handling.
* This is in assembler because if do_page_fault tells us that
@@ -626,16 +661,6 @@ END_FTR_SECTION_IFSET(CPU_FTR_601)
.long ret_from_except
#endif
- .globl sigreturn_exit
-sigreturn_exit:
- subi r1,r3,STACK_FRAME_OVERHEAD
- rlwinm r12,r1,0,0,(31-THREAD_SHIFT) /* current_thread_info() */
- lwz r9,TI_FLAGS(r12)
- andi. r0,r9,_TIF_SYSCALL_T_OR_A
- beq+ ret_from_except_full
- bl do_syscall_trace_leave
- /* fall through */
-
.globl ret_from_except_full
ret_from_except_full:
REST_NVGPRS(r1)
@@ -658,7 +683,7 @@ user_exc_return: /* r10 contains MSR_KERNEL here */
/* Check current_thread_info()->flags */
rlwinm r9,r1,0,0,(31-THREAD_SHIFT)
lwz r9,TI_FLAGS(r9)
- andi. r0,r9,(_TIF_SIGPENDING|_TIF_NEED_RESCHED)
+ andi. r0,r9,(_TIF_SIGPENDING|_TIF_NEED_RESCHED|_TIF_RESTOREALL)
bne do_work
restore_user: