659 lines
18 KiB
ArmAsm
659 lines
18 KiB
ArmAsm
/*
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* Linux/PA-RISC Project (http://www.parisc-linux.org/)
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*
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* System call entry code Copyright (c) Matthew Wilcox 1999 <willy@bofh.ai>
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* Licensed under the GNU GPL.
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* thanks to Philipp Rumpf, Mike Shaver and various others
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* sorry about the wall, puffin..
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*/
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#include <asm/asm-offsets.h>
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#include <asm/unistd.h>
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#include <asm/errno.h>
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#include <asm/page.h>
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#include <asm/psw.h>
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#include <asm/thread_info.h>
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#include <asm/assembly.h>
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#include <asm/processor.h>
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#include <linux/linkage.h>
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/* We fill the empty parts of the gateway page with
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* something that will kill the kernel or a
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* userspace application.
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*/
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#define KILL_INSN break 0,0
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.level LEVEL
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.text
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.import syscall_exit,code
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.import syscall_exit_rfi,code
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/* Linux gateway page is aliased to virtual page 0 in the kernel
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* address space. Since it is a gateway page it cannot be
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* dereferenced, so null pointers will still fault. We start
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* the actual entry point at 0x100. We put break instructions
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* at the beginning of the page to trap null indirect function
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* pointers.
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*/
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.align PAGE_SIZE
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ENTRY(linux_gateway_page)
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/* ADDRESS 0x00 to 0xb0 = 176 bytes / 4 bytes per insn = 44 insns */
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.rept 44
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KILL_INSN
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.endr
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/* ADDRESS 0xb0 to 0xb4, lws uses 1 insns for entry */
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/* Light-weight-syscall entry must always be located at 0xb0 */
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/* WARNING: Keep this number updated with table size changes */
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#define __NR_lws_entries (2)
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lws_entry:
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/* Unconditional branch to lws_start, located on the
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same gateway page */
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b,n lws_start
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/* Fill from 0xb4 to 0xe0 */
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.rept 11
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KILL_INSN
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.endr
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/* This function MUST be located at 0xe0 for glibc's threading
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mechanism to work. DO NOT MOVE THIS CODE EVER! */
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set_thread_pointer:
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gate .+8, %r0 /* increase privilege */
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depi 3, 31, 2, %r31 /* Ensure we return into user mode. */
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be 0(%sr7,%r31) /* return to user space */
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mtctl %r26, %cr27 /* move arg0 to the control register */
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/* Increase the chance of trapping if random jumps occur to this
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address, fill from 0xf0 to 0x100 */
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.rept 4
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KILL_INSN
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.endr
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/* This address must remain fixed at 0x100 for glibc's syscalls to work */
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.align 256
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linux_gateway_entry:
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gate .+8, %r0 /* become privileged */
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mtsp %r0,%sr4 /* get kernel space into sr4 */
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mtsp %r0,%sr5 /* get kernel space into sr5 */
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mtsp %r0,%sr6 /* get kernel space into sr6 */
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mfsp %sr7,%r1 /* save user sr7 */
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mtsp %r1,%sr3 /* and store it in sr3 */
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#ifdef CONFIG_64BIT
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/* for now we can *always* set the W bit on entry to the syscall
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* since we don't support wide userland processes. We could
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* also save the current SM other than in r0 and restore it on
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* exit from the syscall, and also use that value to know
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* whether to do narrow or wide syscalls. -PB
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*/
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ssm PSW_SM_W, %r1
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extrd,u %r1,PSW_W_BIT,1,%r1
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/* sp must be aligned on 4, so deposit the W bit setting into
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* the bottom of sp temporarily */
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or,ev %r1,%r30,%r30
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b,n 1f
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/* The top halves of argument registers must be cleared on syscall
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* entry from narrow executable.
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*/
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depdi 0, 31, 32, %r26
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depdi 0, 31, 32, %r25
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depdi 0, 31, 32, %r24
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depdi 0, 31, 32, %r23
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depdi 0, 31, 32, %r22
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depdi 0, 31, 32, %r21
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1:
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#endif
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mfctl %cr30,%r1
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xor %r1,%r30,%r30 /* ye olde xor trick */
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xor %r1,%r30,%r1
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xor %r1,%r30,%r30
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ldo THREAD_SZ_ALGN+FRAME_SIZE(%r30),%r30 /* set up kernel stack */
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/* N.B.: It is critical that we don't set sr7 to 0 until r30
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* contains a valid kernel stack pointer. It is also
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* critical that we don't start using the kernel stack
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* until after sr7 has been set to 0.
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*/
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mtsp %r0,%sr7 /* get kernel space into sr7 */
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STREGM %r1,FRAME_SIZE(%r30) /* save r1 (usp) here for now */
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mfctl %cr30,%r1 /* get task ptr in %r1 */
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LDREG TI_TASK(%r1),%r1
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/* Save some registers for sigcontext and potential task
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switch (see entry.S for the details of which ones are
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saved/restored). TASK_PT_PSW is zeroed so we can see whether
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a process is on a syscall or not. For an interrupt the real
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PSW value is stored. This is needed for gdb and sys_ptrace. */
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STREG %r0, TASK_PT_PSW(%r1)
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STREG %r2, TASK_PT_GR2(%r1) /* preserve rp */
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STREG %r19, TASK_PT_GR19(%r1)
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LDREGM -FRAME_SIZE(%r30), %r2 /* get users sp back */
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#ifdef CONFIG_64BIT
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extrd,u %r2,63,1,%r19 /* W hidden in bottom bit */
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#if 0
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xor %r19,%r2,%r2 /* clear bottom bit */
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depd,z %r19,1,1,%r19
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std %r19,TASK_PT_PSW(%r1)
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#endif
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#endif
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STREG %r2, TASK_PT_GR30(%r1) /* ... and save it */
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STREG %r20, TASK_PT_GR20(%r1) /* Syscall number */
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STREG %r21, TASK_PT_GR21(%r1)
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STREG %r22, TASK_PT_GR22(%r1)
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STREG %r23, TASK_PT_GR23(%r1) /* 4th argument */
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STREG %r24, TASK_PT_GR24(%r1) /* 3rd argument */
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STREG %r25, TASK_PT_GR25(%r1) /* 2nd argument */
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STREG %r26, TASK_PT_GR26(%r1) /* 1st argument */
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STREG %r27, TASK_PT_GR27(%r1) /* user dp */
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STREG %r28, TASK_PT_GR28(%r1) /* return value 0 */
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STREG %r28, TASK_PT_ORIG_R28(%r1) /* return value 0 (saved for signals) */
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STREG %r29, TASK_PT_GR29(%r1) /* return value 1 */
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STREG %r31, TASK_PT_GR31(%r1) /* preserve syscall return ptr */
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ldo TASK_PT_FR0(%r1), %r27 /* save fpregs from the kernel */
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save_fp %r27 /* or potential task switch */
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mfctl %cr11, %r27 /* i.e. SAR */
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STREG %r27, TASK_PT_SAR(%r1)
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loadgp
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#ifdef CONFIG_64BIT
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ldo -16(%r30),%r29 /* Reference param save area */
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copy %r19,%r2 /* W bit back to r2 */
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#else
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/* no need to save these on stack in wide mode because the first 8
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* args are passed in registers */
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stw %r22, -52(%r30) /* 5th argument */
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stw %r21, -56(%r30) /* 6th argument */
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#endif
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/* Are we being ptraced? */
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mfctl %cr30, %r1
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LDREG TI_TASK(%r1),%r1
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ldw TASK_PTRACE(%r1), %r1
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bb,<,n %r1,31,.Ltracesys
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/* Note! We cannot use the syscall table that is mapped
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nearby since the gateway page is mapped execute-only. */
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#ifdef CONFIG_64BIT
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ldil L%sys_call_table, %r1
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or,= %r2,%r2,%r2
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addil L%(sys_call_table64-sys_call_table), %r1
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ldo R%sys_call_table(%r1), %r19
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or,= %r2,%r2,%r2
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ldo R%sys_call_table64(%r1), %r19
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#else
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ldil L%sys_call_table, %r1
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ldo R%sys_call_table(%r1), %r19
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#endif
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comiclr,>> __NR_Linux_syscalls, %r20, %r0
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b,n .Lsyscall_nosys
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LDREGX %r20(%r19), %r19
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/* If this is a sys_rt_sigreturn call, and the signal was received
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* when not in_syscall, then we want to return via syscall_exit_rfi,
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* not syscall_exit. Signal no. in r20, in_syscall in r25 (see
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* trampoline code in signal.c).
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*/
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ldi __NR_rt_sigreturn,%r2
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comb,= %r2,%r20,.Lrt_sigreturn
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.Lin_syscall:
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ldil L%syscall_exit,%r2
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be 0(%sr7,%r19)
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ldo R%syscall_exit(%r2),%r2
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.Lrt_sigreturn:
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comib,<> 0,%r25,.Lin_syscall
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ldil L%syscall_exit_rfi,%r2
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be 0(%sr7,%r19)
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ldo R%syscall_exit_rfi(%r2),%r2
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/* Note! Because we are not running where we were linked, any
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calls to functions external to this file must be indirect. To
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be safe, we apply the opposite rule to functions within this
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file, with local labels given to them to ensure correctness. */
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.Lsyscall_nosys:
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syscall_nosys:
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ldil L%syscall_exit,%r1
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be R%syscall_exit(%sr7,%r1)
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ldo -ENOSYS(%r0),%r28 /* set errno */
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/* Warning! This trace code is a virtual duplicate of the code above so be
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* sure to maintain both! */
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.Ltracesys:
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tracesys:
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/* Need to save more registers so the debugger can see where we
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* are. This saves only the lower 8 bits of PSW, so that the C
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* bit is still clear on syscalls, and the D bit is set if this
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* full register save path has been executed. We check the D
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* bit on syscall_return_rfi to determine which registers to
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* restore. An interrupt results in a full PSW saved with the
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* C bit set, a non-straced syscall entry results in C and D clear
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* in the saved PSW.
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*/
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ldo -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1 /* get task ptr */
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LDREG TI_TASK(%r1), %r1
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ssm 0,%r2
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STREG %r2,TASK_PT_PSW(%r1) /* Lower 8 bits only!! */
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mfsp %sr0,%r2
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STREG %r2,TASK_PT_SR0(%r1)
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mfsp %sr1,%r2
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STREG %r2,TASK_PT_SR1(%r1)
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mfsp %sr2,%r2
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STREG %r2,TASK_PT_SR2(%r1)
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mfsp %sr3,%r2
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STREG %r2,TASK_PT_SR3(%r1)
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STREG %r2,TASK_PT_SR4(%r1)
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STREG %r2,TASK_PT_SR5(%r1)
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STREG %r2,TASK_PT_SR6(%r1)
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STREG %r2,TASK_PT_SR7(%r1)
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STREG %r2,TASK_PT_IASQ0(%r1)
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STREG %r2,TASK_PT_IASQ1(%r1)
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LDREG TASK_PT_GR31(%r1),%r2
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STREG %r2,TASK_PT_IAOQ0(%r1)
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ldo 4(%r2),%r2
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STREG %r2,TASK_PT_IAOQ1(%r1)
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ldo TASK_REGS(%r1),%r2
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/* reg_save %r2 */
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STREG %r3,PT_GR3(%r2)
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STREG %r4,PT_GR4(%r2)
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STREG %r5,PT_GR5(%r2)
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STREG %r6,PT_GR6(%r2)
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STREG %r7,PT_GR7(%r2)
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STREG %r8,PT_GR8(%r2)
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STREG %r9,PT_GR9(%r2)
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STREG %r10,PT_GR10(%r2)
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STREG %r11,PT_GR11(%r2)
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STREG %r12,PT_GR12(%r2)
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STREG %r13,PT_GR13(%r2)
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STREG %r14,PT_GR14(%r2)
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STREG %r15,PT_GR15(%r2)
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STREG %r16,PT_GR16(%r2)
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STREG %r17,PT_GR17(%r2)
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STREG %r18,PT_GR18(%r2)
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/* Finished saving things for the debugger */
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ldil L%syscall_trace,%r1
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ldil L%tracesys_next,%r2
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be R%syscall_trace(%sr7,%r1)
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ldo R%tracesys_next(%r2),%r2
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tracesys_next:
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ldil L%sys_call_table,%r1
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ldo R%sys_call_table(%r1), %r19
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ldo -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1 /* get task ptr */
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LDREG TI_TASK(%r1), %r1
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LDREG TASK_PT_GR20(%r1), %r20
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LDREG TASK_PT_GR26(%r1), %r26 /* Restore the users args */
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LDREG TASK_PT_GR25(%r1), %r25
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LDREG TASK_PT_GR24(%r1), %r24
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LDREG TASK_PT_GR23(%r1), %r23
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#ifdef CONFIG_64BIT
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LDREG TASK_PT_GR22(%r1), %r22
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LDREG TASK_PT_GR21(%r1), %r21
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ldo -16(%r30),%r29 /* Reference param save area */
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#endif
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comiclr,>>= __NR_Linux_syscalls, %r20, %r0
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b,n .Lsyscall_nosys
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LDREGX %r20(%r19), %r19
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/* If this is a sys_rt_sigreturn call, and the signal was received
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* when not in_syscall, then we want to return via syscall_exit_rfi,
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* not syscall_exit. Signal no. in r20, in_syscall in r25 (see
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* trampoline code in signal.c).
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*/
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ldi __NR_rt_sigreturn,%r2
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comb,= %r2,%r20,.Ltrace_rt_sigreturn
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.Ltrace_in_syscall:
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ldil L%tracesys_exit,%r2
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be 0(%sr7,%r19)
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ldo R%tracesys_exit(%r2),%r2
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/* Do *not* call this function on the gateway page, because it
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makes a direct call to syscall_trace. */
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tracesys_exit:
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ldo -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1 /* get task ptr */
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LDREG TI_TASK(%r1), %r1
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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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bl syscall_trace, %r2
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STREG %r28,TASK_PT_GR28(%r1) /* save return value now */
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ldo -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1 /* get task ptr */
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LDREG TI_TASK(%r1), %r1
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LDREG TASK_PT_GR28(%r1), %r28 /* Restore return val. */
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ldil L%syscall_exit,%r1
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be,n R%syscall_exit(%sr7,%r1)
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.Ltrace_rt_sigreturn:
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comib,<> 0,%r25,.Ltrace_in_syscall
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ldil L%tracesys_sigexit,%r2
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be 0(%sr7,%r19)
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ldo R%tracesys_sigexit(%r2),%r2
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tracesys_sigexit:
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ldo -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1 /* get task ptr */
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LDREG 0(%r1), %r1
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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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bl syscall_trace, %r2
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nop
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ldil L%syscall_exit_rfi,%r1
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be,n R%syscall_exit_rfi(%sr7,%r1)
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/*********************************************************
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Light-weight-syscall code
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r20 - lws number
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r26,r25,r24,r23,r22 - Input registers
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r28 - Function return register
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r21 - Error code.
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Scracth: Any of the above that aren't being
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currently used, including r1.
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Return pointer: r31 (Not usable)
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Error codes returned by entry path:
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ENOSYS - r20 was an invalid LWS number.
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*********************************************************/
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lws_start:
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/* Gate and ensure we return to userspace */
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gate .+8, %r0
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depi 3, 31, 2, %r31 /* Ensure we return to userspace */
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#ifdef CONFIG_64BIT
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/* FIXME: If we are a 64-bit kernel just
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* turn this on unconditionally.
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*/
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ssm PSW_SM_W, %r1
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extrd,u %r1,PSW_W_BIT,1,%r1
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/* sp must be aligned on 4, so deposit the W bit setting into
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* the bottom of sp temporarily */
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or,ev %r1,%r30,%r30
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/* Clip LWS number to a 32-bit value always */
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depdi 0, 31, 32, %r20
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#endif
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/* Is the lws entry number valid? */
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comiclr,>>= __NR_lws_entries, %r20, %r0
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b,n lws_exit_nosys
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/* WARNING: Trashing sr2 and sr3 */
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mfsp %sr7,%r1 /* get userspace into sr3 */
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mtsp %r1,%sr3
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mtsp %r0,%sr2 /* get kernel space into sr2 */
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/* Load table start */
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ldil L%lws_table, %r1
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ldo R%lws_table(%r1), %r28 /* Scratch use of r28 */
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LDREGX %r20(%sr2,r28), %r21 /* Scratch use of r21 */
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/* Jump to lws, lws table pointers already relocated */
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be,n 0(%sr2,%r21)
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lws_exit_nosys:
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ldo -ENOSYS(%r0),%r21 /* set errno */
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/* Fall through: Return to userspace */
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lws_exit:
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#ifdef CONFIG_64BIT
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/* decide whether to reset the wide mode bit
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*
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* For a syscall, the W bit is stored in the lowest bit
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* of sp. Extract it and reset W if it is zero */
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extrd,u,*<> %r30,63,1,%r1
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rsm PSW_SM_W, %r0
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/* now reset the lowest bit of sp if it was set */
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xor %r30,%r1,%r30
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#endif
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be,n 0(%sr3, %r31)
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/***************************************************
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Implementing CAS as an atomic operation:
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%r26 - Address to examine
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%r25 - Old value to check (old)
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%r24 - New value to set (new)
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%r28 - Return prev through this register.
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%r21 - Kernel error code
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If debugging is DISabled:
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%r21 has the following meanings:
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EAGAIN - CAS is busy, ldcw failed, try again.
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EFAULT - Read or write failed.
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If debugging is enabled:
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|
|
|
EDEADLOCK - CAS called recursively.
|
|
EAGAIN && r28 == 1 - CAS is busy. Lock contended.
|
|
EAGAIN && r28 == 2 - CAS is busy. ldcw failed.
|
|
EFAULT - Read or write failed.
|
|
|
|
Scratch: r20, r28, r1
|
|
|
|
****************************************************/
|
|
|
|
/* Do not enable LWS debugging */
|
|
#define ENABLE_LWS_DEBUG 0
|
|
|
|
/* ELF64 Process entry path */
|
|
lws_compare_and_swap64:
|
|
#ifdef CONFIG_64BIT
|
|
b,n lws_compare_and_swap
|
|
#else
|
|
/* If we are not a 64-bit kernel, then we don't
|
|
* implement having 64-bit input registers
|
|
*/
|
|
b,n lws_exit_nosys
|
|
#endif
|
|
|
|
/* ELF32 Process entry path */
|
|
lws_compare_and_swap32:
|
|
#ifdef CONFIG_64BIT
|
|
/* Clip all the input registers */
|
|
depdi 0, 31, 32, %r26
|
|
depdi 0, 31, 32, %r25
|
|
depdi 0, 31, 32, %r24
|
|
#endif
|
|
|
|
lws_compare_and_swap:
|
|
#ifdef CONFIG_SMP
|
|
/* Load start of lock table */
|
|
ldil L%lws_lock_start, %r20
|
|
ldo R%lws_lock_start(%r20), %r28
|
|
|
|
/* Extract four bits from r26 and hash lock (Bits 4-7) */
|
|
extru %r26, 27, 4, %r20
|
|
|
|
/* Find lock to use, the hash is either one of 0 to
|
|
15, multiplied by 16 (keep it 16-byte aligned)
|
|
and add to the lock table offset. */
|
|
shlw %r20, 4, %r20
|
|
add %r20, %r28, %r20
|
|
|
|
# if ENABLE_LWS_DEBUG
|
|
/*
|
|
DEBUG, check for deadlock!
|
|
If the thread register values are the same
|
|
then we were the one that locked it last and
|
|
this is a recurisve call that will deadlock.
|
|
We *must* giveup this call and fail.
|
|
*/
|
|
ldw 4(%sr2,%r20), %r28 /* Load thread register */
|
|
/* WARNING: If cr27 cycles to the same value we have problems */
|
|
mfctl %cr27, %r21 /* Get current thread register */
|
|
cmpb,<>,n %r21, %r28, cas_lock /* Called recursive? */
|
|
b lws_exit /* Return error! */
|
|
ldo -EDEADLOCK(%r0), %r21
|
|
cas_lock:
|
|
cmpb,=,n %r0, %r28, cas_nocontend /* Is nobody using it? */
|
|
ldo 1(%r0), %r28 /* 1st case */
|
|
b lws_exit /* Contended... */
|
|
ldo -EAGAIN(%r0), %r21 /* Spin in userspace */
|
|
cas_nocontend:
|
|
# endif
|
|
/* ENABLE_LWS_DEBUG */
|
|
|
|
LDCW 0(%sr2,%r20), %r28 /* Try to acquire the lock */
|
|
cmpb,<>,n %r0, %r28, cas_action /* Did we get it? */
|
|
cas_wouldblock:
|
|
ldo 2(%r0), %r28 /* 2nd case */
|
|
b lws_exit /* Contended... */
|
|
ldo -EAGAIN(%r0), %r21 /* Spin in userspace */
|
|
#endif
|
|
/* CONFIG_SMP */
|
|
|
|
/*
|
|
prev = *addr;
|
|
if ( prev == old )
|
|
*addr = new;
|
|
return prev;
|
|
*/
|
|
|
|
/* NOTES:
|
|
This all works becuse intr_do_signal
|
|
and schedule both check the return iasq
|
|
and see that we are on the kernel page
|
|
so this process is never scheduled off
|
|
or is ever sent any signal of any sort,
|
|
thus it is wholly atomic from usrspaces
|
|
perspective
|
|
*/
|
|
cas_action:
|
|
#if defined CONFIG_SMP && ENABLE_LWS_DEBUG
|
|
/* DEBUG */
|
|
mfctl %cr27, %r1
|
|
stw %r1, 4(%sr2,%r20)
|
|
#endif
|
|
/* The load and store could fail */
|
|
1: ldw 0(%sr3,%r26), %r28
|
|
sub,<> %r28, %r25, %r0
|
|
2: stw %r24, 0(%sr3,%r26)
|
|
#ifdef CONFIG_SMP
|
|
/* Free lock */
|
|
stw %r20, 0(%sr2,%r20)
|
|
# if ENABLE_LWS_DEBUG
|
|
/* Clear thread register indicator */
|
|
stw %r0, 4(%sr2,%r20)
|
|
# endif
|
|
#endif
|
|
/* Return to userspace, set no error */
|
|
b lws_exit
|
|
copy %r0, %r21
|
|
|
|
3:
|
|
/* Error occured on load or store */
|
|
#ifdef CONFIG_SMP
|
|
/* Free lock */
|
|
stw %r20, 0(%sr2,%r20)
|
|
# if ENABLE_LWS_DEBUG
|
|
stw %r0, 4(%sr2,%r20)
|
|
# endif
|
|
#endif
|
|
b lws_exit
|
|
ldo -EFAULT(%r0),%r21 /* set errno */
|
|
nop
|
|
nop
|
|
nop
|
|
nop
|
|
|
|
/* Two exception table entries, one for the load,
|
|
the other for the store. Either return -EFAULT.
|
|
Each of the entries must be relocated. */
|
|
.section __ex_table,"aw"
|
|
ASM_ULONG_INSN (1b - linux_gateway_page), (3b - linux_gateway_page)
|
|
ASM_ULONG_INSN (2b - linux_gateway_page), (3b - linux_gateway_page)
|
|
.previous
|
|
|
|
|
|
/* Make sure nothing else is placed on this page */
|
|
.align PAGE_SIZE
|
|
END(linux_gateway_page)
|
|
ENTRY(end_linux_gateway_page)
|
|
|
|
/* Relocate symbols assuming linux_gateway_page is mapped
|
|
to virtual address 0x0 */
|
|
|
|
#define LWS_ENTRY(_name_) ASM_ULONG_INSN (lws_##_name_ - linux_gateway_page)
|
|
|
|
.section .rodata,"a"
|
|
|
|
.align PAGE_SIZE
|
|
/* Light-weight-syscall table */
|
|
/* Start of lws table. */
|
|
ENTRY(lws_table)
|
|
LWS_ENTRY(compare_and_swap32) /* 0 - ELF32 Atomic compare and swap */
|
|
LWS_ENTRY(compare_and_swap64) /* 1 - ELF64 Atomic compare and swap */
|
|
END(lws_table)
|
|
/* End of lws table */
|
|
|
|
.align PAGE_SIZE
|
|
ENTRY(sys_call_table)
|
|
#include "syscall_table.S"
|
|
END(sys_call_table)
|
|
|
|
#ifdef CONFIG_64BIT
|
|
.align PAGE_SIZE
|
|
ENTRY(sys_call_table64)
|
|
#define SYSCALL_TABLE_64BIT
|
|
#include "syscall_table.S"
|
|
END(sys_call_table64)
|
|
#endif
|
|
|
|
#ifdef CONFIG_SMP
|
|
/*
|
|
All light-weight-syscall atomic operations
|
|
will use this set of locks
|
|
*/
|
|
.section .data
|
|
.align PAGE_SIZE
|
|
ENTRY(lws_lock_start)
|
|
/* lws locks */
|
|
.align 16
|
|
.rept 16
|
|
/* Keep locks aligned at 16-bytes */
|
|
.word 1
|
|
.word 0
|
|
.word 0
|
|
.word 0
|
|
.endr
|
|
END(lws_lock_start)
|
|
.previous
|
|
#endif
|
|
/* CONFIG_SMP for lws_lock_start */
|
|
|
|
.end
|
|
|
|
|