From ff0ab8af9c3f36e7b6f716c3b9e8811a4202eec6 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Fri, 5 Oct 2012 18:55:57 -0400 Subject: [PATCH] parisc: optimizations in copy_thread() and friends * in user thread case the registers had been copied as part of task_struct already; no need to do it in copy_thread(). * no need to store kernel stack pointer into regs->r21; we know its offset anyway. * no need to clobber r3 in sys_fork_wrapper and friends - r28 will do just as well and *it* will be overwritten anyway. * no need to mess with storing the return address for child - it should just use syscall_exit. * no need to bother with separate stack frame for sys_clone() - just branch there and be done with that. * no need to bother with wrapper_exit - we need it only on the child_return, so let's just do it there. * use the same ksp for kernel threads and userland ones, while we are at it, and let ret_from_kernel_execve() go through the normal syscall_exit. More straightforward is better here... [fixes from jejb folded] Signed-off-by: Al Viro --- arch/parisc/kernel/entry.S | 86 ++++++++---------------------------- arch/parisc/kernel/process.c | 28 ++++-------- 2 files changed, 27 insertions(+), 87 deletions(-) diff --git a/arch/parisc/kernel/entry.S b/arch/parisc/kernel/entry.S index 7d22e97347b..47fb6ddcf12 100644 --- a/arch/parisc/kernel/entry.S +++ b/arch/parisc/kernel/entry.S @@ -719,7 +719,7 @@ ENTRY(ret_from_kernel_thread) BL schedule_tail, %r2 nop - LDREG TI_TASK-THREAD_SZ_ALGN(%r30), %r1 + LDREG TI_TASK-THREAD_SZ_ALGN-FRAME_SIZE(%r30), %r1 LDREG TASK_PT_GR25(%r1), %r26 #ifdef CONFIG_64BIT LDREG TASK_PT_GR27(%r1), %r27 @@ -743,9 +743,8 @@ ENDPROC(ret_from_kernel_thread) ENTRY(ret_from_kernel_execve) mfctl %cr30, %r1 - ldo THREAD_SZ_ALGN(%r1), %r30 - b intr_return /* forward */ - copy %r26,%r16 /* pt_regs into r16 */ + b syscall_exit /* forward */ + ldo THREAD_SZ_ALGN+FRAME_SIZE(%r1), %r30 ENDPROC(ret_from_kernel_execve) @@ -1709,39 +1708,13 @@ ENTRY(sys_fork_wrapper) LDREG TI_TASK-THREAD_SZ_ALGN-FRAME_SIZE(%r30), %r1 ldo TASK_REGS(%r1),%r1 reg_save %r1 - mfctl %cr27, %r3 - STREG %r3, PT_CR27(%r1) - - STREG %r2,-RP_OFFSET(%r30) - ldo FRAME_SIZE(%r30),%r30 -#ifdef CONFIG_64BIT - ldo -16(%r30),%r29 /* Reference param save area */ -#endif - - /* These are call-clobbered registers and therefore - also syscall-clobbered (we hope). */ - STREG %r2,PT_GR19(%r1) /* save for child */ - STREG %r30,PT_GR21(%r1) + mfctl %cr27, %r28 + STREG %r28, PT_CR27(%r1) LDREG PT_GR30(%r1),%r25 copy %r1,%r24 - BL sys_clone,%r2 + b sys_clone ldi SIGCHLD,%r26 - - LDREG -RP_OFFSET-FRAME_SIZE(%r30),%r2 -wrapper_exit: - ldo -FRAME_SIZE(%r30),%r30 /* get the stackframe */ - LDREG TI_TASK-THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1 - ldo TASK_REGS(%r1),%r1 /* get pt regs */ - - LDREG PT_CR27(%r1), %r3 - mtctl %r3, %cr27 - reg_restore %r1 - - /* strace expects syscall # to be preserved in r20 */ - ldi __NR_fork,%r20 - bv %r0(%r2) - STREG %r20,PT_GR20(%r1) ENDPROC(sys_fork_wrapper) /* Set the return value for the child */ @@ -1749,9 +1722,13 @@ ENTRY(child_return) BL schedule_tail, %r2 nop - LDREG TI_TASK-THREAD_SZ_ALGN-FRAME_SIZE-FRAME_SIZE(%r30), %r1 - LDREG TASK_PT_GR19(%r1),%r2 - b wrapper_exit + LDREG TI_TASK-THREAD_SZ_ALGN-FRAME_SIZE(%r30), %r1 + ldo TASK_REGS(%r1),%r1 /* get pt regs */ + + LDREG PT_CR27(%r1), %r3 + mtctl %r3, %cr27 + reg_restore %r1 + b syscall_exit copy %r0,%r28 ENDPROC(child_return) @@ -1760,23 +1737,10 @@ ENTRY(sys_clone_wrapper) LDREG TI_TASK-THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1 ldo TASK_REGS(%r1),%r1 /* get pt regs */ reg_save %r1 - mfctl %cr27, %r3 - STREG %r3, PT_CR27(%r1) - - STREG %r2,-RP_OFFSET(%r30) - ldo FRAME_SIZE(%r30),%r30 -#ifdef CONFIG_64BIT - ldo -16(%r30),%r29 /* Reference param save area */ -#endif - - /* WARNING - Clobbers r19 and r21, userspace must save these! */ - STREG %r2,PT_GR19(%r1) /* save for child */ - STREG %r30,PT_GR21(%r1) - BL sys_clone,%r2 + mfctl %cr27, %r28 + STREG %r28, PT_CR27(%r1) + b sys_clone copy %r1,%r24 - - b wrapper_exit - LDREG -RP_OFFSET-FRAME_SIZE(%r30),%r2 ENDPROC(sys_clone_wrapper) @@ -1784,23 +1748,11 @@ ENTRY(sys_vfork_wrapper) LDREG TI_TASK-THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1 ldo TASK_REGS(%r1),%r1 /* get pt regs */ reg_save %r1 - mfctl %cr27, %r3 - STREG %r3, PT_CR27(%r1) - - STREG %r2,-RP_OFFSET(%r30) - ldo FRAME_SIZE(%r30),%r30 -#ifdef CONFIG_64BIT - ldo -16(%r30),%r29 /* Reference param save area */ -#endif + mfctl %cr27, %r28 + STREG %r28, PT_CR27(%r1) - STREG %r2,PT_GR19(%r1) /* save for child */ - STREG %r30,PT_GR21(%r1) - - BL sys_vfork,%r2 + b sys_vfork copy %r1,%r26 - - b wrapper_exit - LDREG -RP_OFFSET-FRAME_SIZE(%r30),%r2 ENDPROC(sys_vfork_wrapper) diff --git a/arch/parisc/kernel/process.c b/arch/parisc/kernel/process.c index 44e8534c52e..38db36f6430 100644 --- a/arch/parisc/kernel/process.c +++ b/arch/parisc/kernel/process.c @@ -52,6 +52,7 @@ #include #include +#include #include #include #include @@ -253,14 +254,16 @@ copy_thread(unsigned long clone_flags, unsigned long usp, #ifdef CONFIG_HPUX extern void * const hpux_child_return; #endif - - if (unlikely((p->flags & PF_KTHREAD) && usp != 0)) { + if (unlikely(p->flags & PF_KTHREAD)) { memset(cregs, 0, sizeof(struct pt_regs)); + if (!usp) /* idle thread */ + return 0; + /* kernel thread */ - cregs->ksp = (unsigned long)stack + THREAD_SZ_ALGN; /* Must exit via ret_from_kernel_thread in order * to call schedule_tail() */ + cregs->ksp = (unsigned long)stack + THREAD_SZ_ALGN + FRAME_SIZE; cregs->kpc = (unsigned long) &ret_from_kernel_thread; /* * Copy function and argument to be called from @@ -275,22 +278,8 @@ copy_thread(unsigned long clone_flags, unsigned long usp, cregs->gr[25] = arg; } else { /* user thread */ - /* - * Note that the fork wrappers are responsible - * for setting gr[21]. - */ - - *cregs = *pregs; - - /* Set the return value for the child. Note that this is not - actually restored by the syscall exit path, but we put it - here for consistency in case of signals. */ - cregs->gr[28] = 0; /* child */ - - /* Use same stack depth as parent */ - cregs->ksp = (unsigned long)stack - + (pregs->gr[21] & (THREAD_SIZE - 1)); cregs->gr[30] = usp; + cregs->ksp = (unsigned long)stack + THREAD_SZ_ALGN + FRAME_SIZE; if (personality(p->personality) == PER_HPUX) { #ifdef CONFIG_HPUX cregs->kpc = (unsigned long) &hpux_child_return; @@ -302,8 +291,7 @@ copy_thread(unsigned long clone_flags, unsigned long usp, } /* Setup thread TLS area from the 4th parameter in clone */ if (clone_flags & CLONE_SETTLS) - cregs->cr27 = pregs->gr[23]; - + cregs->cr27 = pregs->gr[23]; } return 0; -- 2.46.0