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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-09-25 11:55:37 +00:00
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 <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro
parent
7f1f311ac7
commit
ff0ab8af9c
2 changed files with 27 additions and 87 deletions
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@ -719,7 +719,7 @@ ENTRY(ret_from_kernel_thread)
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BL schedule_tail, %r2
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nop
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LDREG TI_TASK-THREAD_SZ_ALGN(%r30), %r1
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LDREG TI_TASK-THREAD_SZ_ALGN-FRAME_SIZE(%r30), %r1
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LDREG TASK_PT_GR25(%r1), %r26
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#ifdef CONFIG_64BIT
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LDREG TASK_PT_GR27(%r1), %r27
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@ -743,9 +743,8 @@ ENDPROC(ret_from_kernel_thread)
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ENTRY(ret_from_kernel_execve)
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mfctl %cr30, %r1
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ldo THREAD_SZ_ALGN(%r1), %r30
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b intr_return /* forward */
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copy %r26,%r16 /* pt_regs into r16 */
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b syscall_exit /* forward */
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ldo THREAD_SZ_ALGN+FRAME_SIZE(%r1), %r30
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ENDPROC(ret_from_kernel_execve)
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@ -1709,39 +1708,13 @@ ENTRY(sys_fork_wrapper)
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LDREG TI_TASK-THREAD_SZ_ALGN-FRAME_SIZE(%r30), %r1
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ldo TASK_REGS(%r1),%r1
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reg_save %r1
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mfctl %cr27, %r3
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STREG %r3, PT_CR27(%r1)
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STREG %r2,-RP_OFFSET(%r30)
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ldo FRAME_SIZE(%r30),%r30
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#ifdef CONFIG_64BIT
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ldo -16(%r30),%r29 /* Reference param save area */
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#endif
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/* These are call-clobbered registers and therefore
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also syscall-clobbered (we hope). */
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STREG %r2,PT_GR19(%r1) /* save for child */
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STREG %r30,PT_GR21(%r1)
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mfctl %cr27, %r28
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STREG %r28, PT_CR27(%r1)
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LDREG PT_GR30(%r1),%r25
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copy %r1,%r24
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BL sys_clone,%r2
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b sys_clone
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ldi SIGCHLD,%r26
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LDREG -RP_OFFSET-FRAME_SIZE(%r30),%r2
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wrapper_exit:
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ldo -FRAME_SIZE(%r30),%r30 /* get the stackframe */
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LDREG TI_TASK-THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1
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ldo TASK_REGS(%r1),%r1 /* get pt regs */
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LDREG PT_CR27(%r1), %r3
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mtctl %r3, %cr27
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reg_restore %r1
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/* strace expects syscall # to be preserved in r20 */
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ldi __NR_fork,%r20
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bv %r0(%r2)
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STREG %r20,PT_GR20(%r1)
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ENDPROC(sys_fork_wrapper)
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/* Set the return value for the child */
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@ -1749,9 +1722,13 @@ ENTRY(child_return)
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BL schedule_tail, %r2
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nop
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LDREG TI_TASK-THREAD_SZ_ALGN-FRAME_SIZE-FRAME_SIZE(%r30), %r1
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LDREG TASK_PT_GR19(%r1),%r2
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b wrapper_exit
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LDREG TI_TASK-THREAD_SZ_ALGN-FRAME_SIZE(%r30), %r1
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ldo TASK_REGS(%r1),%r1 /* get pt regs */
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LDREG PT_CR27(%r1), %r3
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mtctl %r3, %cr27
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reg_restore %r1
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b syscall_exit
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copy %r0,%r28
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ENDPROC(child_return)
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@ -1760,23 +1737,10 @@ ENTRY(sys_clone_wrapper)
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LDREG TI_TASK-THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1
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ldo TASK_REGS(%r1),%r1 /* get pt regs */
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reg_save %r1
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mfctl %cr27, %r3
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STREG %r3, PT_CR27(%r1)
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STREG %r2,-RP_OFFSET(%r30)
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ldo FRAME_SIZE(%r30),%r30
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#ifdef CONFIG_64BIT
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ldo -16(%r30),%r29 /* Reference param save area */
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#endif
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/* WARNING - Clobbers r19 and r21, userspace must save these! */
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STREG %r2,PT_GR19(%r1) /* save for child */
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STREG %r30,PT_GR21(%r1)
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BL sys_clone,%r2
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mfctl %cr27, %r28
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STREG %r28, PT_CR27(%r1)
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b sys_clone
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copy %r1,%r24
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b wrapper_exit
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LDREG -RP_OFFSET-FRAME_SIZE(%r30),%r2
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ENDPROC(sys_clone_wrapper)
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@ -1784,23 +1748,11 @@ ENTRY(sys_vfork_wrapper)
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LDREG TI_TASK-THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1
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ldo TASK_REGS(%r1),%r1 /* get pt regs */
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reg_save %r1
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mfctl %cr27, %r3
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STREG %r3, PT_CR27(%r1)
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mfctl %cr27, %r28
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STREG %r28, PT_CR27(%r1)
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STREG %r2,-RP_OFFSET(%r30)
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ldo FRAME_SIZE(%r30),%r30
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#ifdef CONFIG_64BIT
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ldo -16(%r30),%r29 /* Reference param save area */
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#endif
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STREG %r2,PT_GR19(%r1) /* save for child */
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STREG %r30,PT_GR21(%r1)
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BL sys_vfork,%r2
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b sys_vfork
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copy %r1,%r26
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b wrapper_exit
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LDREG -RP_OFFSET-FRAME_SIZE(%r30),%r2
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ENDPROC(sys_vfork_wrapper)
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@ -52,6 +52,7 @@
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#include <asm/io.h>
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#include <asm/asm-offsets.h>
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#include <asm/assembly.h>
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#include <asm/pdc.h>
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#include <asm/pdc_chassis.h>
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#include <asm/pgalloc.h>
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@ -253,14 +254,16 @@ copy_thread(unsigned long clone_flags, unsigned long usp,
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#ifdef CONFIG_HPUX
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extern void * const hpux_child_return;
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#endif
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if (unlikely((p->flags & PF_KTHREAD) && usp != 0)) {
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if (unlikely(p->flags & PF_KTHREAD)) {
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memset(cregs, 0, sizeof(struct pt_regs));
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if (!usp) /* idle thread */
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return 0;
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/* kernel thread */
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cregs->ksp = (unsigned long)stack + THREAD_SZ_ALGN;
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/* Must exit via ret_from_kernel_thread in order
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* to call schedule_tail()
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*/
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cregs->ksp = (unsigned long)stack + THREAD_SZ_ALGN + FRAME_SIZE;
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cregs->kpc = (unsigned long) &ret_from_kernel_thread;
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/*
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* Copy function and argument to be called from
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@ -275,22 +278,8 @@ copy_thread(unsigned long clone_flags, unsigned long usp,
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cregs->gr[25] = arg;
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} else {
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/* user thread */
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/*
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* Note that the fork wrappers are responsible
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* for setting gr[21].
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*/
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*cregs = *pregs;
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/* Set the return value for the child. Note that this is not
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actually restored by the syscall exit path, but we put it
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here for consistency in case of signals. */
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cregs->gr[28] = 0; /* child */
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/* Use same stack depth as parent */
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cregs->ksp = (unsigned long)stack
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+ (pregs->gr[21] & (THREAD_SIZE - 1));
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cregs->gr[30] = usp;
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cregs->ksp = (unsigned long)stack + THREAD_SZ_ALGN + FRAME_SIZE;
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if (personality(p->personality) == PER_HPUX) {
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#ifdef CONFIG_HPUX
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cregs->kpc = (unsigned long) &hpux_child_return;
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@ -302,8 +291,7 @@ copy_thread(unsigned long clone_flags, unsigned long usp,
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}
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/* Setup thread TLS area from the 4th parameter in clone */
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if (clone_flags & CLONE_SETTLS)
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cregs->cr27 = pregs->gr[23];
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cregs->cr27 = pregs->gr[23];
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}
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return 0;
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