| /* |
| * Linux/PA-RISC Project (http://www.parisc-linux.org/) |
| * |
| * System call entry code / Linux gateway page |
| * Copyright (c) Matthew Wilcox 1999 <willy@bofh.ai> |
| * Licensed under the GNU GPL. |
| * thanks to Philipp Rumpf, Mike Shaver and various others |
| * sorry about the wall, puffin.. |
| */ |
| |
| /* |
| How does the Linux gateway page on PA-RISC work? |
| ------------------------------------------------ |
| The Linux gateway page on PA-RISC is "special". |
| It actually has PAGE_GATEWAY bits set (this is linux terminology; in parisc |
| terminology it's Execute, promote to PL0) in the page map. So anything |
| executing on this page executes with kernel level privilege (there's more to it |
| than that: to have this happen, you also have to use a branch with a ,gate |
| completer to activate the privilege promotion). The upshot is that everything |
| that runs on the gateway page runs at kernel privilege but with the current |
| user process address space (although you have access to kernel space via %sr2). |
| For the 0x100 syscall entry, we redo the space registers to point to the kernel |
| address space (preserving the user address space in %sr3), move to wide mode if |
| required, save the user registers and branch into the kernel syscall entry |
| point. For all the other functions, we execute at kernel privilege but don't |
| flip address spaces. The basic upshot of this is that these code snippets are |
| executed atomically (because the kernel can't be pre-empted) and they may |
| perform architecturally forbidden (to PL3) operations (like setting control |
| registers). |
| */ |
| |
| |
| #include <asm/asm-offsets.h> |
| #include <asm/unistd.h> |
| #include <asm/errno.h> |
| #include <asm/page.h> |
| #include <asm/psw.h> |
| #include <asm/thread_info.h> |
| #include <asm/assembly.h> |
| #include <asm/processor.h> |
| #include <asm/cache.h> |
| |
| #include <linux/linkage.h> |
| |
| /* We fill the empty parts of the gateway page with |
| * something that will kill the kernel or a |
| * userspace application. |
| */ |
| #define KILL_INSN break 0,0 |
| |
| .level LEVEL |
| |
| .text |
| |
| .import syscall_exit,code |
| .import syscall_exit_rfi,code |
| |
| /* Linux gateway page is aliased to virtual page 0 in the kernel |
| * address space. Since it is a gateway page it cannot be |
| * dereferenced, so null pointers will still fault. We start |
| * the actual entry point at 0x100. We put break instructions |
| * at the beginning of the page to trap null indirect function |
| * pointers. |
| */ |
| |
| .align PAGE_SIZE |
| ENTRY(linux_gateway_page) |
| |
| /* ADDRESS 0x00 to 0xb0 = 176 bytes / 4 bytes per insn = 44 insns */ |
| .rept 44 |
| KILL_INSN |
| .endr |
| |
| /* ADDRESS 0xb0 to 0xb8, lws uses two insns for entry */ |
| /* Light-weight-syscall entry must always be located at 0xb0 */ |
| /* WARNING: Keep this number updated with table size changes */ |
| #define __NR_lws_entries (3) |
| |
| lws_entry: |
| gate lws_start, %r0 /* increase privilege */ |
| depi 3, 31, 2, %r31 /* Ensure we return into user mode. */ |
| |
| /* Fill from 0xb8 to 0xe0 */ |
| .rept 10 |
| KILL_INSN |
| .endr |
| |
| /* This function MUST be located at 0xe0 for glibc's threading |
| mechanism to work. DO NOT MOVE THIS CODE EVER! */ |
| set_thread_pointer: |
| gate .+8, %r0 /* increase privilege */ |
| depi 3, 31, 2, %r31 /* Ensure we return into user mode. */ |
| be 0(%sr7,%r31) /* return to user space */ |
| mtctl %r26, %cr27 /* move arg0 to the control register */ |
| |
| /* Increase the chance of trapping if random jumps occur to this |
| address, fill from 0xf0 to 0x100 */ |
| .rept 4 |
| KILL_INSN |
| .endr |
| |
| /* This address must remain fixed at 0x100 for glibc's syscalls to work */ |
| .align LINUX_GATEWAY_ADDR |
| linux_gateway_entry: |
| gate .+8, %r0 /* become privileged */ |
| mtsp %r0,%sr4 /* get kernel space into sr4 */ |
| mtsp %r0,%sr5 /* get kernel space into sr5 */ |
| mtsp %r0,%sr6 /* get kernel space into sr6 */ |
| |
| #ifdef CONFIG_64BIT |
| /* for now we can *always* set the W bit on entry to the syscall |
| * since we don't support wide userland processes. We could |
| * also save the current SM other than in r0 and restore it on |
| * exit from the syscall, and also use that value to know |
| * whether to do narrow or wide syscalls. -PB |
| */ |
| ssm PSW_SM_W, %r1 |
| extrd,u %r1,PSW_W_BIT,1,%r1 |
| /* sp must be aligned on 4, so deposit the W bit setting into |
| * the bottom of sp temporarily */ |
| or,ev %r1,%r30,%r30 |
| b,n 1f |
| /* The top halves of argument registers must be cleared on syscall |
| * entry from narrow executable. |
| */ |
| depdi 0, 31, 32, %r26 |
| depdi 0, 31, 32, %r25 |
| depdi 0, 31, 32, %r24 |
| depdi 0, 31, 32, %r23 |
| depdi 0, 31, 32, %r22 |
| depdi 0, 31, 32, %r21 |
| 1: |
| #endif |
| |
| /* We use a rsm/ssm pair to prevent sr3 from being clobbered |
| * by external interrupts. |
| */ |
| mfsp %sr7,%r1 /* save user sr7 */ |
| rsm PSW_SM_I, %r0 /* disable interrupts */ |
| mtsp %r1,%sr3 /* and store it in sr3 */ |
| |
| mfctl %cr30,%r1 |
| xor %r1,%r30,%r30 /* ye olde xor trick */ |
| xor %r1,%r30,%r1 |
| xor %r1,%r30,%r30 |
| |
| ldo THREAD_SZ_ALGN+FRAME_SIZE(%r30),%r30 /* set up kernel stack */ |
| |
| /* N.B.: It is critical that we don't set sr7 to 0 until r30 |
| * contains a valid kernel stack pointer. It is also |
| * critical that we don't start using the kernel stack |
| * until after sr7 has been set to 0. |
| */ |
| |
| mtsp %r0,%sr7 /* get kernel space into sr7 */ |
| ssm PSW_SM_I, %r0 /* enable interrupts */ |
| STREGM %r1,FRAME_SIZE(%r30) /* save r1 (usp) here for now */ |
| mfctl %cr30,%r1 /* get task ptr in %r1 */ |
| LDREG TI_TASK(%r1),%r1 |
| |
| /* Save some registers for sigcontext and potential task |
| switch (see entry.S for the details of which ones are |
| saved/restored). TASK_PT_PSW is zeroed so we can see whether |
| a process is on a syscall or not. For an interrupt the real |
| PSW value is stored. This is needed for gdb and sys_ptrace. */ |
| STREG %r0, TASK_PT_PSW(%r1) |
| STREG %r2, TASK_PT_GR2(%r1) /* preserve rp */ |
| STREG %r19, TASK_PT_GR19(%r1) |
| |
| LDREGM -FRAME_SIZE(%r30), %r2 /* get users sp back */ |
| #ifdef CONFIG_64BIT |
| extrd,u %r2,63,1,%r19 /* W hidden in bottom bit */ |
| #if 0 |
| xor %r19,%r2,%r2 /* clear bottom bit */ |
| depd,z %r19,1,1,%r19 |
| std %r19,TASK_PT_PSW(%r1) |
| #endif |
| #endif |
| STREG %r2, TASK_PT_GR30(%r1) /* ... and save it */ |
| |
| STREG %r20, TASK_PT_GR20(%r1) /* Syscall number */ |
| STREG %r21, TASK_PT_GR21(%r1) |
| STREG %r22, TASK_PT_GR22(%r1) |
| STREG %r23, TASK_PT_GR23(%r1) /* 4th argument */ |
| STREG %r24, TASK_PT_GR24(%r1) /* 3rd argument */ |
| STREG %r25, TASK_PT_GR25(%r1) /* 2nd argument */ |
| STREG %r26, TASK_PT_GR26(%r1) /* 1st argument */ |
| STREG %r27, TASK_PT_GR27(%r1) /* user dp */ |
| STREG %r28, TASK_PT_GR28(%r1) /* return value 0 */ |
| STREG %r0, TASK_PT_ORIG_R28(%r1) /* don't prohibit restarts */ |
| STREG %r29, TASK_PT_GR29(%r1) /* return value 1 */ |
| STREG %r31, TASK_PT_GR31(%r1) /* preserve syscall return ptr */ |
| |
| ldo TASK_PT_FR0(%r1), %r27 /* save fpregs from the kernel */ |
| save_fp %r27 /* or potential task switch */ |
| |
| mfctl %cr11, %r27 /* i.e. SAR */ |
| STREG %r27, TASK_PT_SAR(%r1) |
| |
| loadgp |
| |
| #ifdef CONFIG_64BIT |
| ldo -16(%r30),%r29 /* Reference param save area */ |
| copy %r19,%r2 /* W bit back to r2 */ |
| #else |
| /* no need to save these on stack in wide mode because the first 8 |
| * args are passed in registers */ |
| stw %r22, -52(%r30) /* 5th argument */ |
| stw %r21, -56(%r30) /* 6th argument */ |
| #endif |
| |
| /* Are we being ptraced? */ |
| mfctl %cr30, %r1 |
| LDREG TI_FLAGS(%r1),%r1 |
| ldi _TIF_SYSCALL_TRACE_MASK, %r19 |
| and,COND(=) %r1, %r19, %r0 |
| b,n .Ltracesys |
| |
| /* Note! We cannot use the syscall table that is mapped |
| nearby since the gateway page is mapped execute-only. */ |
| |
| #ifdef CONFIG_64BIT |
| ldil L%sys_call_table, %r1 |
| or,= %r2,%r2,%r2 |
| addil L%(sys_call_table64-sys_call_table), %r1 |
| ldo R%sys_call_table(%r1), %r19 |
| or,= %r2,%r2,%r2 |
| ldo R%sys_call_table64(%r1), %r19 |
| #else |
| ldil L%sys_call_table, %r1 |
| ldo R%sys_call_table(%r1), %r19 |
| #endif |
| comiclr,>> __NR_Linux_syscalls, %r20, %r0 |
| b,n .Lsyscall_nosys |
| |
| LDREGX %r20(%r19), %r19 |
| |
| /* If this is a sys_rt_sigreturn call, and the signal was received |
| * when not in_syscall, then we want to return via syscall_exit_rfi, |
| * not syscall_exit. Signal no. in r20, in_syscall in r25 (see |
| * trampoline code in signal.c). |
| */ |
| ldi __NR_rt_sigreturn,%r2 |
| comb,= %r2,%r20,.Lrt_sigreturn |
| .Lin_syscall: |
| ldil L%syscall_exit,%r2 |
| be 0(%sr7,%r19) |
| ldo R%syscall_exit(%r2),%r2 |
| .Lrt_sigreturn: |
| comib,<> 0,%r25,.Lin_syscall |
| ldil L%syscall_exit_rfi,%r2 |
| be 0(%sr7,%r19) |
| ldo R%syscall_exit_rfi(%r2),%r2 |
| |
| /* Note! Because we are not running where we were linked, any |
| calls to functions external to this file must be indirect. To |
| be safe, we apply the opposite rule to functions within this |
| file, with local labels given to them to ensure correctness. */ |
| |
| .Lsyscall_nosys: |
| syscall_nosys: |
| ldil L%syscall_exit,%r1 |
| be R%syscall_exit(%sr7,%r1) |
| ldo -ENOSYS(%r0),%r28 /* set errno */ |
| |
| |
| /* Warning! This trace code is a virtual duplicate of the code above so be |
| * sure to maintain both! */ |
| .Ltracesys: |
| tracesys: |
| /* Need to save more registers so the debugger can see where we |
| * are. This saves only the lower 8 bits of PSW, so that the C |
| * bit is still clear on syscalls, and the D bit is set if this |
| * full register save path has been executed. We check the D |
| * bit on syscall_return_rfi to determine which registers to |
| * restore. An interrupt results in a full PSW saved with the |
| * C bit set, a non-straced syscall entry results in C and D clear |
| * in the saved PSW. |
| */ |
| ldo -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1 /* get task ptr */ |
| LDREG TI_TASK(%r1), %r1 |
| ssm 0,%r2 |
| STREG %r2,TASK_PT_PSW(%r1) /* Lower 8 bits only!! */ |
| mfsp %sr0,%r2 |
| STREG %r2,TASK_PT_SR0(%r1) |
| mfsp %sr1,%r2 |
| STREG %r2,TASK_PT_SR1(%r1) |
| mfsp %sr2,%r2 |
| STREG %r2,TASK_PT_SR2(%r1) |
| mfsp %sr3,%r2 |
| STREG %r2,TASK_PT_SR3(%r1) |
| STREG %r2,TASK_PT_SR4(%r1) |
| STREG %r2,TASK_PT_SR5(%r1) |
| STREG %r2,TASK_PT_SR6(%r1) |
| STREG %r2,TASK_PT_SR7(%r1) |
| STREG %r2,TASK_PT_IASQ0(%r1) |
| STREG %r2,TASK_PT_IASQ1(%r1) |
| LDREG TASK_PT_GR31(%r1),%r2 |
| STREG %r2,TASK_PT_IAOQ0(%r1) |
| ldo 4(%r2),%r2 |
| STREG %r2,TASK_PT_IAOQ1(%r1) |
| ldo TASK_REGS(%r1),%r2 |
| /* reg_save %r2 */ |
| STREG %r3,PT_GR3(%r2) |
| STREG %r4,PT_GR4(%r2) |
| STREG %r5,PT_GR5(%r2) |
| STREG %r6,PT_GR6(%r2) |
| STREG %r7,PT_GR7(%r2) |
| STREG %r8,PT_GR8(%r2) |
| STREG %r9,PT_GR9(%r2) |
| STREG %r10,PT_GR10(%r2) |
| STREG %r11,PT_GR11(%r2) |
| STREG %r12,PT_GR12(%r2) |
| STREG %r13,PT_GR13(%r2) |
| STREG %r14,PT_GR14(%r2) |
| STREG %r15,PT_GR15(%r2) |
| STREG %r16,PT_GR16(%r2) |
| STREG %r17,PT_GR17(%r2) |
| STREG %r18,PT_GR18(%r2) |
| /* Finished saving things for the debugger */ |
| |
| copy %r2,%r26 |
| ldil L%do_syscall_trace_enter,%r1 |
| ldil L%tracesys_next,%r2 |
| be R%do_syscall_trace_enter(%sr7,%r1) |
| ldo R%tracesys_next(%r2),%r2 |
| |
| tracesys_next: |
| /* do_syscall_trace_enter either returned the syscallno, or -1L, |
| * so we skip restoring the PT_GR20 below, since we pulled it from |
| * task->thread.regs.gr[20] above. |
| */ |
| copy %ret0,%r20 |
| ldil L%sys_call_table,%r1 |
| ldo R%sys_call_table(%r1), %r19 |
| |
| ldo -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1 /* get task ptr */ |
| LDREG TI_TASK(%r1), %r1 |
| LDREG TASK_PT_GR28(%r1), %r28 /* Restore return value */ |
| LDREG TASK_PT_GR26(%r1), %r26 /* Restore the users args */ |
| LDREG TASK_PT_GR25(%r1), %r25 |
| LDREG TASK_PT_GR24(%r1), %r24 |
| LDREG TASK_PT_GR23(%r1), %r23 |
| LDREG TASK_PT_GR22(%r1), %r22 |
| LDREG TASK_PT_GR21(%r1), %r21 |
| #ifdef CONFIG_64BIT |
| ldo -16(%r30),%r29 /* Reference param save area */ |
| #else |
| stw %r22, -52(%r30) /* 5th argument */ |
| stw %r21, -56(%r30) /* 6th argument */ |
| #endif |
| |
| cmpib,COND(=),n -1,%r20,tracesys_exit /* seccomp may have returned -1 */ |
| comiclr,>> __NR_Linux_syscalls, %r20, %r0 |
| b,n .Ltracesys_nosys |
| |
| LDREGX %r20(%r19), %r19 |
| |
| /* If this is a sys_rt_sigreturn call, and the signal was received |
| * when not in_syscall, then we want to return via syscall_exit_rfi, |
| * not syscall_exit. Signal no. in r20, in_syscall in r25 (see |
| * trampoline code in signal.c). |
| */ |
| ldi __NR_rt_sigreturn,%r2 |
| comb,= %r2,%r20,.Ltrace_rt_sigreturn |
| .Ltrace_in_syscall: |
| ldil L%tracesys_exit,%r2 |
| be 0(%sr7,%r19) |
| ldo R%tracesys_exit(%r2),%r2 |
| |
| .Ltracesys_nosys: |
| ldo -ENOSYS(%r0),%r28 /* set errno */ |
| |
| /* Do *not* call this function on the gateway page, because it |
| makes a direct call to syscall_trace. */ |
| |
| tracesys_exit: |
| ldo -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1 /* get task ptr */ |
| LDREG TI_TASK(%r1), %r1 |
| #ifdef CONFIG_64BIT |
| ldo -16(%r30),%r29 /* Reference param save area */ |
| #endif |
| ldo TASK_REGS(%r1),%r26 |
| BL do_syscall_trace_exit,%r2 |
| STREG %r28,TASK_PT_GR28(%r1) /* save return value now */ |
| ldo -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1 /* get task ptr */ |
| LDREG TI_TASK(%r1), %r1 |
| LDREG TASK_PT_GR28(%r1), %r28 /* Restore return val. */ |
| |
| ldil L%syscall_exit,%r1 |
| be,n R%syscall_exit(%sr7,%r1) |
| |
| .Ltrace_rt_sigreturn: |
| comib,<> 0,%r25,.Ltrace_in_syscall |
| ldil L%tracesys_sigexit,%r2 |
| be 0(%sr7,%r19) |
| ldo R%tracesys_sigexit(%r2),%r2 |
| |
| tracesys_sigexit: |
| ldo -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1 /* get task ptr */ |
| LDREG TI_TASK(%r1), %r1 |
| #ifdef CONFIG_64BIT |
| ldo -16(%r30),%r29 /* Reference param save area */ |
| #endif |
| BL do_syscall_trace_exit,%r2 |
| ldo TASK_REGS(%r1),%r26 |
| |
| ldil L%syscall_exit_rfi,%r1 |
| be,n R%syscall_exit_rfi(%sr7,%r1) |
| |
| |
| /********************************************************* |
| 32/64-bit Light-Weight-Syscall ABI |
| |
| * - Indicates a hint for userspace inline asm |
| implementations. |
| |
| Syscall number (caller-saves) |
| - %r20 |
| * In asm clobber. |
| |
| Argument registers (caller-saves) |
| - %r26, %r25, %r24, %r23, %r22 |
| * In asm input. |
| |
| Return registers (caller-saves) |
| - %r28 (return), %r21 (errno) |
| * In asm output. |
| |
| Caller-saves registers |
| - %r1, %r27, %r29 |
| - %r2 (return pointer) |
| - %r31 (ble link register) |
| * In asm clobber. |
| |
| Callee-saves registers |
| - %r3-%r18 |
| - %r30 (stack pointer) |
| * Not in asm clobber. |
| |
| If userspace is 32-bit: |
| Callee-saves registers |
| - %r19 (32-bit PIC register) |
| |
| Differences from 32-bit calling convention: |
| - Syscall number in %r20 |
| - Additional argument register %r22 (arg4) |
| - Callee-saves %r19. |
| |
| If userspace is 64-bit: |
| Callee-saves registers |
| - %r27 (64-bit PIC register) |
| |
| Differences from 64-bit calling convention: |
| - Syscall number in %r20 |
| - Additional argument register %r22 (arg4) |
| - Callee-saves %r27. |
| |
| Error codes returned by entry path: |
| |
| ENOSYS - r20 was an invalid LWS number. |
| |
| *********************************************************/ |
| lws_start: |
| |
| #ifdef CONFIG_64BIT |
| /* FIXME: If we are a 64-bit kernel just |
| * turn this on unconditionally. |
| */ |
| ssm PSW_SM_W, %r1 |
| extrd,u %r1,PSW_W_BIT,1,%r1 |
| /* sp must be aligned on 4, so deposit the W bit setting into |
| * the bottom of sp temporarily */ |
| or,ev %r1,%r30,%r30 |
| |
| /* Clip LWS number to a 32-bit value always */ |
| depdi 0, 31, 32, %r20 |
| #endif |
| |
| /* Is the lws entry number valid? */ |
| comiclr,>> __NR_lws_entries, %r20, %r0 |
| b,n lws_exit_nosys |
| |
| /* Load table start */ |
| ldil L%lws_table, %r1 |
| ldo R%lws_table(%r1), %r28 /* Scratch use of r28 */ |
| LDREGX %r20(%sr2,r28), %r21 /* Scratch use of r21 */ |
| |
| /* Jump to lws, lws table pointers already relocated */ |
| be,n 0(%sr2,%r21) |
| |
| lws_exit_nosys: |
| ldo -ENOSYS(%r0),%r21 /* set errno */ |
| /* Fall through: Return to userspace */ |
| |
| lws_exit: |
| #ifdef CONFIG_64BIT |
| /* decide whether to reset the wide mode bit |
| * |
| * For a syscall, the W bit is stored in the lowest bit |
| * of sp. Extract it and reset W if it is zero */ |
| extrd,u,*<> %r30,63,1,%r1 |
| rsm PSW_SM_W, %r0 |
| /* now reset the lowest bit of sp if it was set */ |
| xor %r30,%r1,%r30 |
| #endif |
| be,n 0(%sr7, %r31) |
| |
| |
| |
| /*************************************************** |
| Implementing 32bit CAS as an atomic operation: |
| |
| %r26 - Address to examine |
| %r25 - Old value to check (old) |
| %r24 - New value to set (new) |
| %r28 - Return prev through this register. |
| %r21 - Kernel error code |
| |
| If debugging is DISabled: |
| |
| %r21 has the following meanings: |
| |
| EAGAIN - CAS is busy, ldcw failed, try again. |
| EFAULT - Read or write failed. |
| |
| If debugging is enabled: |
| |
| 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 |
| * have 64-bit input registers, and calling |
| * the 64-bit LWS CAS returns ENOSYS. |
| */ |
| 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: |
| /* 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 */ |
| |
| rsm PSW_SM_I, %r0 /* Disable interrupts */ |
| /* COW breaks can cause contention on UP systems */ |
| 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 */ |
| ssm PSW_SM_I, %r0 |
| b lws_exit /* Contended... */ |
| ldo -EAGAIN(%r0), %r21 /* Spin in userspace */ |
| |
| /* |
| 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,ma 0(%r26), %r28 |
| sub,<> %r28, %r25, %r0 |
| 2: stw,ma %r24, 0(%r26) |
| /* Free lock */ |
| stw,ma %r20, 0(%sr2,%r20) |
| #if ENABLE_LWS_DEBUG |
| /* Clear thread register indicator */ |
| stw %r0, 4(%sr2,%r20) |
| #endif |
| /* Enable interrupts */ |
| ssm PSW_SM_I, %r0 |
| /* Return to userspace, set no error */ |
| b lws_exit |
| copy %r0, %r21 |
| |
| 3: |
| /* Error occurred on load or store */ |
| /* Free lock */ |
| stw %r20, 0(%sr2,%r20) |
| #if ENABLE_LWS_DEBUG |
| stw %r0, 4(%sr2,%r20) |
| #endif |
| ssm PSW_SM_I, %r0 |
| 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. */ |
| ASM_EXCEPTIONTABLE_ENTRY(1b-linux_gateway_page, 3b-linux_gateway_page) |
| ASM_EXCEPTIONTABLE_ENTRY(2b-linux_gateway_page, 3b-linux_gateway_page) |
| |
| |
| /*************************************************** |
| New CAS implementation which uses pointers and variable size |
| information. The value pointed by old and new MUST NOT change |
| while performing CAS. The lock only protect the value at %r26. |
| |
| %r26 - Address to examine |
| %r25 - Pointer to the value to check (old) |
| %r24 - Pointer to the value to set (new) |
| %r23 - Size of the variable (0/1/2/3 for 8/16/32/64 bit) |
| %r28 - Return non-zero on failure |
| %r21 - Kernel error code |
| |
| %r21 has the following meanings: |
| |
| EAGAIN - CAS is busy, ldcw failed, try again. |
| EFAULT - Read or write failed. |
| |
| Scratch: r20, r22, r28, r29, r1, fr4 (32bit for 64bit CAS only) |
| |
| ****************************************************/ |
| |
| /* ELF32 Process entry path */ |
| lws_compare_and_swap_2: |
| #ifdef CONFIG_64BIT |
| /* Clip the input registers */ |
| depdi 0, 31, 32, %r26 |
| depdi 0, 31, 32, %r25 |
| depdi 0, 31, 32, %r24 |
| depdi 0, 31, 32, %r23 |
| #endif |
| |
| /* Check the validity of the size pointer */ |
| subi,>>= 4, %r23, %r0 |
| b,n lws_exit_nosys |
| |
| /* Jump to the functions which will load the old and new values into |
| registers depending on the their size */ |
| shlw %r23, 2, %r29 |
| blr %r29, %r0 |
| nop |
| |
| /* 8bit load */ |
| 4: ldb 0(%r25), %r25 |
| b cas2_lock_start |
| 5: ldb 0(%r24), %r24 |
| nop |
| nop |
| nop |
| nop |
| nop |
| |
| /* 16bit load */ |
| 6: ldh 0(%r25), %r25 |
| b cas2_lock_start |
| 7: ldh 0(%r24), %r24 |
| nop |
| nop |
| nop |
| nop |
| nop |
| |
| /* 32bit load */ |
| 8: ldw 0(%r25), %r25 |
| b cas2_lock_start |
| 9: ldw 0(%r24), %r24 |
| nop |
| nop |
| nop |
| nop |
| nop |
| |
| /* 64bit load */ |
| #ifdef CONFIG_64BIT |
| 10: ldd 0(%r25), %r25 |
| 11: ldd 0(%r24), %r24 |
| #else |
| /* Load new value into r22/r23 - high/low */ |
| 10: ldw 0(%r25), %r22 |
| 11: ldw 4(%r25), %r23 |
| /* Load new value into fr4 for atomic store later */ |
| 12: flddx 0(%r24), %fr4 |
| #endif |
| |
| cas2_lock_start: |
| /* 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 |
| |
| rsm PSW_SM_I, %r0 /* Disable interrupts */ |
| /* COW breaks can cause contention on UP systems */ |
| LDCW 0(%sr2,%r20), %r28 /* Try to acquire the lock */ |
| cmpb,<>,n %r0, %r28, cas2_action /* Did we get it? */ |
| cas2_wouldblock: |
| ldo 2(%r0), %r28 /* 2nd case */ |
| ssm PSW_SM_I, %r0 |
| b lws_exit /* Contended... */ |
| ldo -EAGAIN(%r0), %r21 /* Spin in userspace */ |
| |
| /* |
| 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 |
| */ |
| cas2_action: |
| /* Jump to the correct function */ |
| blr %r29, %r0 |
| /* Set %r28 as non-zero for now */ |
| ldo 1(%r0),%r28 |
| |
| /* 8bit CAS */ |
| 13: ldb,ma 0(%r26), %r29 |
| sub,= %r29, %r25, %r0 |
| b,n cas2_end |
| 14: stb,ma %r24, 0(%r26) |
| b cas2_end |
| copy %r0, %r28 |
| nop |
| nop |
| |
| /* 16bit CAS */ |
| 15: ldh,ma 0(%r26), %r29 |
| sub,= %r29, %r25, %r0 |
| b,n cas2_end |
| 16: sth,ma %r24, 0(%r26) |
| b cas2_end |
| copy %r0, %r28 |
| nop |
| nop |
| |
| /* 32bit CAS */ |
| 17: ldw,ma 0(%r26), %r29 |
| sub,= %r29, %r25, %r0 |
| b,n cas2_end |
| 18: stw,ma %r24, 0(%r26) |
| b cas2_end |
| copy %r0, %r28 |
| nop |
| nop |
| |
| /* 64bit CAS */ |
| #ifdef CONFIG_64BIT |
| 19: ldd,ma 0(%r26), %r29 |
| sub,*= %r29, %r25, %r0 |
| b,n cas2_end |
| 20: std,ma %r24, 0(%r26) |
| copy %r0, %r28 |
| #else |
| /* Compare first word */ |
| 19: ldw,ma 0(%r26), %r29 |
| sub,= %r29, %r22, %r0 |
| b,n cas2_end |
| /* Compare second word */ |
| 20: ldw,ma 4(%r26), %r29 |
| sub,= %r29, %r23, %r0 |
| b,n cas2_end |
| /* Perform the store */ |
| 21: fstdx %fr4, 0(%r26) |
| copy %r0, %r28 |
| #endif |
| |
| cas2_end: |
| /* Free lock */ |
| stw,ma %r20, 0(%sr2,%r20) |
| /* Enable interrupts */ |
| ssm PSW_SM_I, %r0 |
| /* Return to userspace, set no error */ |
| b lws_exit |
| copy %r0, %r21 |
| |
| 22: |
| /* Error occurred on load or store */ |
| /* Free lock */ |
| stw %r20, 0(%sr2,%r20) |
| ssm PSW_SM_I, %r0 |
| ldo 1(%r0),%r28 |
| b lws_exit |
| ldo -EFAULT(%r0),%r21 /* set errno */ |
| nop |
| nop |
| nop |
| |
| /* Exception table entries, for the load and store, return EFAULT. |
| Each of the entries must be relocated. */ |
| ASM_EXCEPTIONTABLE_ENTRY(4b-linux_gateway_page, 22b-linux_gateway_page) |
| ASM_EXCEPTIONTABLE_ENTRY(5b-linux_gateway_page, 22b-linux_gateway_page) |
| ASM_EXCEPTIONTABLE_ENTRY(6b-linux_gateway_page, 22b-linux_gateway_page) |
| ASM_EXCEPTIONTABLE_ENTRY(7b-linux_gateway_page, 22b-linux_gateway_page) |
| ASM_EXCEPTIONTABLE_ENTRY(8b-linux_gateway_page, 22b-linux_gateway_page) |
| ASM_EXCEPTIONTABLE_ENTRY(9b-linux_gateway_page, 22b-linux_gateway_page) |
| ASM_EXCEPTIONTABLE_ENTRY(10b-linux_gateway_page, 22b-linux_gateway_page) |
| ASM_EXCEPTIONTABLE_ENTRY(11b-linux_gateway_page, 22b-linux_gateway_page) |
| ASM_EXCEPTIONTABLE_ENTRY(13b-linux_gateway_page, 22b-linux_gateway_page) |
| ASM_EXCEPTIONTABLE_ENTRY(14b-linux_gateway_page, 22b-linux_gateway_page) |
| ASM_EXCEPTIONTABLE_ENTRY(15b-linux_gateway_page, 22b-linux_gateway_page) |
| ASM_EXCEPTIONTABLE_ENTRY(16b-linux_gateway_page, 22b-linux_gateway_page) |
| ASM_EXCEPTIONTABLE_ENTRY(17b-linux_gateway_page, 22b-linux_gateway_page) |
| ASM_EXCEPTIONTABLE_ENTRY(18b-linux_gateway_page, 22b-linux_gateway_page) |
| ASM_EXCEPTIONTABLE_ENTRY(19b-linux_gateway_page, 22b-linux_gateway_page) |
| ASM_EXCEPTIONTABLE_ENTRY(20b-linux_gateway_page, 22b-linux_gateway_page) |
| #ifndef CONFIG_64BIT |
| ASM_EXCEPTIONTABLE_ENTRY(12b-linux_gateway_page, 22b-linux_gateway_page) |
| ASM_EXCEPTIONTABLE_ENTRY(21b-linux_gateway_page, 22b-linux_gateway_page) |
| #endif |
| |
| /* 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 8 |
| /* Light-weight-syscall table */ |
| /* Start of lws table. */ |
| ENTRY(lws_table) |
| LWS_ENTRY(compare_and_swap32) /* 0 - ELF32 Atomic 32bit CAS */ |
| LWS_ENTRY(compare_and_swap64) /* 1 - ELF64 Atomic 32bit CAS */ |
| LWS_ENTRY(compare_and_swap_2) /* 2 - ELF32 Atomic 64bit CAS */ |
| END(lws_table) |
| /* End of lws table */ |
| |
| .align 8 |
| ENTRY(sys_call_table) |
| .export sys_call_table,data |
| #include "syscall_table.S" |
| END(sys_call_table) |
| |
| #ifdef CONFIG_64BIT |
| .align 8 |
| ENTRY(sys_call_table64) |
| #define SYSCALL_TABLE_64BIT |
| #include "syscall_table.S" |
| END(sys_call_table64) |
| #endif |
| |
| /* |
| All light-weight-syscall atomic operations |
| will use this set of locks |
| |
| NOTE: The lws_lock_start symbol must be |
| at least 16-byte aligned for safe use |
| with ldcw. |
| */ |
| .section .data |
| .align L1_CACHE_BYTES |
| ENTRY(lws_lock_start) |
| /* lws locks */ |
| .rept 16 |
| /* Keep locks aligned at 16-bytes */ |
| .word 1 |
| .word 0 |
| .word 0 |
| .word 0 |
| .endr |
| END(lws_lock_start) |
| .previous |
| |
| .end |
| |
| |
