diff options
Diffstat (limited to 'target/linux/ubicom32/files/arch/ubicom32/kernel/ubicom32_syscall.S')
| -rw-r--r-- | target/linux/ubicom32/files/arch/ubicom32/kernel/ubicom32_syscall.S | 694 |
1 files changed, 694 insertions, 0 deletions
diff --git a/target/linux/ubicom32/files/arch/ubicom32/kernel/ubicom32_syscall.S b/target/linux/ubicom32/files/arch/ubicom32/kernel/ubicom32_syscall.S new file mode 100644 index 000000000..870f66c8f --- /dev/null +++ b/target/linux/ubicom32/files/arch/ubicom32/kernel/ubicom32_syscall.S @@ -0,0 +1,694 @@ +/* + * arch/ubicom32/kernel/ubicom32_syscall.S + * <TODO: Replace with short file description> + * + * (C) Copyright 2009, Ubicom, Inc. + * + * This file is part of the Ubicom32 Linux Kernel Port. + * + * The Ubicom32 Linux Kernel Port is free software: you can redistribute + * it and/or modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation, either version 2 of the + * License, or (at your option) any later version. + * + * The Ubicom32 Linux Kernel Port is distributed in the hope that it + * will be useful, but WITHOUT ANY WARRANTY; without even the implied + * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See + * the GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with the Ubicom32 Linux Kernel Port. If not, + * see <http://www.gnu.org/licenses/>. + * + * Ubicom32 implementation derived from (with many thanks): + * arch/m68knommu + * arch/blackfin + * arch/parisc + */ +#include <linux/sys.h> +#include <linux/linkage.h> +#include <linux/unistd.h> + +#include <asm/ubicom32-common.h> +#include <asm/thread_info.h> +#include <asm/asm-offsets.h> +#include <asm/range-protect.h> + +/* + * __old_system_call() + */ + .section .old_syscall_entry.text, "ax", @progbits +#ifdef CONFIG_OLD_40400010_SYSTEM_CALL +__old_system_call: + call a3, system_call + .size __old_system_call, . - __old_system_call ; +#else + /* + * something that will crash the userspace application, but + * should not take down the kernel, if protection is enabled + * this will never even get executed. + */ + .long 0xFABBCCDE ; illegal instruction + bkpt #-1 ; we will never get here +#endif + +/* + * system_call() + */ + .section .syscall_entry.text, "ax", @progbits + .global system_call +system_call: + /* + * Regular ABI rules for function calls apply for syscall. d8 holds + * the syscall number. We will use that to index into the syscall table. + * d0 - d5 hold the parameters. + * + * First we get the current thread_info and swap to the kernel stack. + * This is done by reading the current thread and looking up the ksp + * from the sw_ksp array and storing it in a3. + * + * Then we reserve space for the syscall context a struct pt_regs and + * save it using a4 initially and later as sp. + * Once sp is set to the kernel sp we can leave the critical section. + * + * For the user case the kernel stack will have the following layout. + * + * a3 ksp[0] +-----------------------+ + * | Thread info area | + * | struct thread_info | + * +-----------------------+ + * : : + * | Kernel Stack Area | + * | | + * a4 / sp >>> +-----------------------+ + * | Context save area | + * | struct pt_reg | + * ksp[THREAD_SIZE-8] +-----------------------+ + * | 8 Byte Buffer Zone | + * ksp[THREAD_SIZE] +-----------------------+ + + * + * For kernel syscalls the layout is as follows. + * + * a3 ksp[0] +-----------------------+ + * | Thread info area | + * | struct thread_info | + * +-----------------------+ + * : : + * | Kernel Stack Area | + * | | + * a4 / sp >>> +-----------------------+ + * | Context save area | + * | struct pt_reg | + * sp at syscall entry +-----------------------+ + * | Callers Kernel Stack | + * : : + * + * Once the context is saved we optionally call syscall_trace and setup + * the exit routine and jump to the syscall. + */ + + /* + * load the base address for sw_ksp into a3 + * Note.. we cannot access it just yet as protection is still on. + */ + moveai a3, #%hi(sw_ksp) + lea.1 a3, %lo(sw_ksp)(a3) + + /* + * Enter critical section . + * + * The 'critical' aspects here are the switching the to the ksp and + * changing the protection registers, these both use per thread + * information so we need to protect from a context switch. For now this + * is done using the global atomic lock. + */ + atomic_lock_acquire + + thread_get_self d15 ; Load current thread number +#ifdef CONFIG_PROTECT_KERNEL + lsl.4 d9, #1, d15 ; Convert to thread bit + enable_kernel_ranges d9 +#endif + /* + * in order to reduce the size of code in the syscall section we get + * out of it right now + */ + call a4, __system_call_bottom_half + .size system_call, . - system_call + + .section .text.__system_call_bottom_half, "ax", @progbits +__system_call_bottom_half: + + /* + * We need to Determine if this is a kernel syscall or user syscall. + * Start by loading the pointer for the thread_info structure for the + * current process in to a3. + */ + move.4 a3, (a3, d15) ; a3 = sw_ksp[d15] + + /* + * Now if this is a kernel thread the same value can be a acheived by + * masking off the lower bits on the current stack pointer. + */ + movei d9, #(~(ASM_THREAD_SIZE-1)) ; load mask + and.4 d9, sp, d9 ; apply mask + + /* + * d9 now has the masked version of the sp. If this is identical to + * what is in a3 then don't switch to ksp as we are already in the + * kernel. + */ + sub.4 #0, a3, d9 + + /* + * if d9 and a3 are not equal. We are usespace and have to shift to + * ksp. + */ + jmpne.t 1f + + /* + * Kernel Syscall. + * + * The kernel has called this routine. We have to pdec space for pt_regs + * from sp. + */ + pdec a4, PT_SIZE(sp) ; a4 = ksp - PT_SIZE + jmpt.t 2f + + /* + * Userspace Syscall. + * + * Add THREAD_SIZE and subtract PT_SIZE to create the proper ksp + */ +1: movei d15, #(ASM_THREAD_SIZE - 8 - PT_SIZE) + lea.1 a4, (a3, d15) ; a4 = ksp + d15 + + /* + * Replace user stack pointer with kernel stack pointer (a4) + * Load -1 into frame_type in save area to indicate this is system call + * frame. + */ +2: move.4 PT_A7(a4), a7 ; Save old sp/A7 on kernel stack + move.4 PT_FRAME_TYPE(a4), #-1 ; Set the frame type. + move.4 sp, a4 ; Change to ksp. + /* + * We are now officially back in the kernel! + */ + + /* + * Now that we are on the ksp we can leave the critical section + */ + atomic_lock_release + + /* + * We need to save a0 because we need to be able to restore it in + * the event that we need to handle a signal. It's not generally + * a callee-saved register but is the GOT pointer. + */ + move.4 PT_A0(sp), a0 ; Save A0 on kernel stack + + /* + * We still need to save d10-d13, a1, a2, a5, a6 in the kernel frame + * for this process, we also save the system call params in the case of + * syscall restart. (note a7 was saved above) + */ + move.4 PT_A1(sp), a1 ; Save A1 on kernel stack + move.4 PT_A2(sp), a2 ; Save A2 on kernel stack + move.4 PT_A5(sp), a5 ; Save A5 on kernel stack + move.4 PT_A6(sp), a6 ; Save A6 on kernel stack + move.4 PT_PC(sp), a5 ; Save A5 at the PC location + move.4 PT_D10(sp), d10 ; Save D10 on kernel stack + move.4 PT_D11(sp), d11 ; Save D11 on kernel stack + move.4 PT_D12(sp), d12 ; Save D12 on kernel stack + move.4 PT_D13(sp), d13 ; Save D13 on kernel stack + + /* + * Now save the syscall parameters + */ + move.4 PT_D0(sp), d0 ; Save d0 on kernel stack + move.4 PT_ORIGINAL_D0(sp), d0 ; Save d0 on kernel stack + move.4 PT_D1(sp), d1 ; Save d1 on kernel stack + move.4 PT_D2(sp), d2 ; Save d2 on kernel stack + move.4 PT_D3(sp), d3 ; Save d3 on kernel stack + move.4 PT_D4(sp), d4 ; Save d4 on kernel stack + move.4 PT_D5(sp), d5 ; Save d5 on kernel stack + move.4 PT_D8(sp), d8 ; Save d8 on kernel stack + + /* + * Test if syscalls are being traced and if they are jump to syscall + * trace (it will comeback here) + */ + btst TI_FLAGS(a3), #ASM_TIF_SYSCALL_TRACE + jmpne.f .Lsystem_call__trace +.Lsystem_call__trace_complete: + /* + * Check for a valid call number [ 0 <= syscall_number < NR_syscalls ] + */ + cmpi d8, #0 + jmplt.f 3f + cmpi d8, #NR_syscalls + jmplt.t 4f + + /* + * They have passed an invalid number. Call sys_ni_syscall staring by + * load a4 with the base address of sys_ni_syscall + */ +3: moveai a4, #%hi(sys_ni_syscall) + lea.1 a4, %lo(sys_ni_syscall)(a4) + jmpt.t 5f ; Jump to regular processing + + /* + * Validated syscall, load the syscall table base address into a3 and + * read the syscall ptr out. + */ +4: moveai a3, #%hi(sys_call_table) + lea.1 a3, %lo(sys_call_table)(a3) ; a3 = sys_call_table + move.4 a4, (a3, d8) ; a4 = sys_call_table[d8] + + /* + * Before calling the syscall, setup a5 so that syscall_exit is called + * on return from syscall + */ +5: moveai a5, #%hi(syscall_exit) ; Setup return address + lea.1 a5, %lo(syscall_exit)(a5) ; from system call + + /* + * If the syscall is __NR_rt_rigreturn then we have to test d1 to + * figure out if we have to change change the return routine to restore + * all registers. + */ + cmpi d8, #__NR_rt_sigreturn + jmpeq.f 6f + + /* + * Launch system call (it will return through a5 - syscall_exit) + */ + calli a3, 0(a4) + + /* + * System call is rt_sigreturn. Test d1. If it is 1 we have to + * change the return address to restore_all_registers + */ +6: cmpi d1, #1 + jmpne.t 7f + + moveai a5, #%hi(restore_all_registers) ; Setup return address + lea.1 a5, %lo(restore_all_registers)(a5) ; to restore_all_registers. + + /* + * Launch system call (it will return through a5) + */ +7: calli a3, 0(a4) ; Launch system call + +.Lsystem_call__trace: + /* + * Syscalls are being traced. + * Call syscall_trace, (return here) + */ + call a5, syscall_trace + + /* + * Restore syscall state (it would have been discarded during the + * syscall trace) + */ + move.4 d0, PT_D0(sp) ; Restore d0 from kernel stack + move.4 d1, PT_D1(sp) ; Restore d1 from kernel stack + move.4 d2, PT_D2(sp) ; Restore d2 from kernel stack + move.4 d3, PT_D3(sp) ; Restore d3 from kernel stack + move.4 d4, PT_D4(sp) ; Restore d4 from kernel stack + move.4 d5, PT_D5(sp) ; Restore d5 from kernel stack + /* add this back if we ever have a syscall with 7 args */ + move.4 d8, PT_D8(sp) ; Restore d8 from kernel stack + + /* + * return to syscall + */ + jmpt.t .Lsystem_call__trace_complete + .size __system_call_bottom_half, . - __system_call_bottom_half + +/* + * syscall_exit() + */ + .section .text.syscall_exit + .global syscall_exit +syscall_exit: + /* + * d0 contains the return value. We should move that into the kernel + * stack d0 location. We will be transitioning from kernel to user + * mode. Test the flags and see if we have to call schedule. If we are + * going to truly exit then all that has to be done is that from the + * kernel stack we have to restore d0, a0, a1, a2, a5, a6 and sp (a7)bb + * and then return via a5. + */ + + /* + * Save d0 to pt_regs + */ + move.4 PT_D0(sp), d0 ; Save d0 into the kernel stack + + /* + * load the thread_info structure by masking off the THREAD_SIZE + * bits. + * + * Note: we used to push a1, but now we don't as we are going + * to eventually restore it to the userspace a1. + */ + movei d9, #(~(ASM_THREAD_SIZE-1)) + and.4 a1, sp, d9 + + /* + * Are any interesting bits set on TI flags, if there are jump + * aside to post_processing. + */ + move.4 d9, #(_TIF_SYSCALL_TRACE | _TIF_NEED_RESCHED | _TIF_SIGPENDING) + and.4 #0, TI_FLAGS(a1), d9 + jmpne.f .Lsyscall_exit__post_processing ; jump to handler +.Lsyscall_exit__post_processing_complete: + + move.4 d0, PT_D0(sp) ; Restore D0 from kernel stack + move.4 d1, PT_D1(sp) ; Restore d1 from kernel stack + move.4 d2, PT_D2(sp) ; Restore d2 from kernel stack + move.4 d3, PT_D3(sp) ; Restore d3 from kernel stack + move.4 d4, PT_D4(sp) ; Restore d4 from kernel stack + move.4 d5, PT_D5(sp) ; Restore d5 from kernel stack + move.4 d8, PT_D8(sp) ; Restore d8 from kernel stack + move.4 d10, PT_D10(sp) ; Restore d10 from kernel stack + move.4 d11, PT_D11(sp) ; Restore d11 from kernel stack + move.4 d12, PT_D12(sp) ; Restore d12 from kernel stack + move.4 d13, PT_D13(sp) ; Restore d13 from kernel stack + move.4 a1, PT_A1(sp) ; Restore A1 from kernel stack + move.4 a2, PT_A2(sp) ; Restore A2 from kernel stack + move.4 a5, PT_A5(sp) ; Restore A5 from kernel stack + move.4 a6, PT_A6(sp) ; Restore A6 from kernel stack + move.4 a0, PT_A0(sp) ; Restore A6 from kernel stack + + /* + * this is only for debug, and could be removed for production builds + */ + move.4 PT_FRAME_TYPE(sp), #0 ; invalidate frame_type + +#ifdef CONFIG_PROTECT_KERNEL + + call a4, __syscall_exit_bottom_half + + .section .kernel_unprotected, "ax", @progbits +__syscall_exit_bottom_half: + /* + * Enter critical section + */ + atomic_lock_acquire + disable_kernel_ranges_for_current d15 +#endif + /* + * Lastly restore userspace stack ptr + * + * Note: that when protection is on we need to hold the lock around the + * stack swap as well because otherwise the protection could get + * inadvertently disabled again at the end of a context switch. + */ + move.4 a7, PT_A7(sp) ; Restore A7 from kernel stack + + /* + * We are now officially back in userspace! + */ + +#ifdef CONFIG_PROTECT_KERNEL + /* + * Leave critical section and return to user space. + */ + atomic_lock_release +#endif + calli a5, 0(a5) ; Back to userspace code. + + bkpt #-1 ; we will never get here + + /* + * Post syscall processing. (unlikely part of syscall_exit) + * + * Are we tracing syscalls. If TIF_SYSCALL_TRACE is set, call + * syscall_trace routine and return here. + */ + .section .text.syscall_exit, "ax", @progbits +.Lsyscall_exit__post_processing: + btst TI_FLAGS(a1), #ASM_TIF_SYSCALL_TRACE + jmpeq.t 1f + call a5, syscall_trace + + /* + * Do we need to resched ie call schedule. If TIF_NEED_RESCHED is set, + * call the scheduler, it will come back here. + */ +1: btst TI_FLAGS(a1), #ASM_TIF_NEED_RESCHED + jmpeq.t 2f + call a5, schedule + + /* + * Do we need to post a signal, if TIF_SIGPENDING is set call the + * do_signal. + */ +2: btst TI_FLAGS(a1), #ASM_TIF_SIGPENDING + jmpeq.t .Lsyscall_exit__post_processing_complete + + /* + * setup the do signal call + */ + move.4 d0, #0 ; oldset pointer is NULL + lea.1 d1, (sp) ; d1 is the regs pointer. + call a5, do_signal + + jmpt.t .Lsyscall_exit__post_processing_complete + +/* .size syscall_exit, . - syscall_exit */ + +/* + * kernel_execve() + * kernel_execv is called when we the kernel is starting a + * userspace application. + */ + .section .kernel_unprotected, "ax", @progbits + .global kernel_execve +kernel_execve: + move.4 -4(sp)++, a5 ; Save return address + /* + * Call execve + */ + movei d8, #__NR_execve ; call execve + call a5, system_call + move.4 a5, (sp)4++ + + /* + * protection was enabled again at syscall exit, but we want + * to return to kernel so we enable it again. + */ +#ifdef CONFIG_PROTECT_KERNEL + /* + * We are entering the kernel so we need to disable the protection. + * Enter critical section, disable ranges and leave critical section. + */ + call a3, __enable_kernel_ranges ; and jump back to kernel +#else + ret a5 ; jump back to the kernel +#endif + + .size kernel_execve, . - kernel_execve + +/* + * signal_trampoline() + * + * Deals with transitioning from to userspace signal handlers and returning + * to userspace, only called from the kernel. + * + */ + .section .kernel_unprotected, "ax", @progbits + .global signal_trampoline +signal_trampoline: + /* + * signal_trampoline is called when we are jumping from the kernel to + * the userspace signal handler. + * + * The following registers are relevant. (set setup_rt_frame) + * sp is the user space stack not the kernel stack + * d0 = signal number + * d1 = siginfo_t * + * d2 = ucontext * + * d3 = the user space signal handler + * a0 is set to the GOT if userspace application is FDPIC, otherwise 0 + * a3 is set to the FD for the signal if userspace application is FDPIC + */ +#ifdef CONFIG_PROTECT_KERNEL + /* + * We are leaving the kernel so we need to enable the protection. + * Enter critical section, disable ranges and leave critical section. + */ + atomic_lock_acquire ; Enter critical section + disable_kernel_ranges_for_current d15 ; disable kernel ranges + atomic_lock_release ; Leave critical section +#endif + /* + * The signal handler pointer is in register d3 so tranfer it to a4 and + * call it + */ + movea a4, d3 ; signal handler + calli a5, 0(a4) + + /* + * Return to userspace through rt_syscall which is stored on top of the + * stack d1 contains ret_via_interrupt status. + */ + move.4 d8, (sp) ; d8 (syscall #) = rt_syscall + move.4 d1, 4(sp) ; d1 = ret_via_interrupt + call a5, system_call ; as we are 'in' the kernel + ; we can call kernel_syscall + + bkpt #-1 ; will never get here. + .size signal_trampoline, . - signal_trampoline + +/* + * kernel_thread_helper() + * + * Entry point for kernel threads (only referenced by kernel_thread()). + * + * On execution d0 will be 0, d1 will be the argument to be passed to the + * kernel function. + * d2 contains the kernel function that needs to get called. + * d3 will contain address to do_exit which needs to get moved into a5. + * + * On return from fork the child thread d0 will be 0. We call this dummy + * function which in turn loads the argument + */ + .section .kernel_unprotected, "ax", @progbits + .global kernel_thread_helper +kernel_thread_helper: + /* + * Create a kernel thread. This is called from ret_from_vfork (a + * userspace return routine) so we need to put it in an unprotected + * section and re-enable protection before calling the vector in d2. + */ + +#ifdef CONFIG_PROTECT_KERNEL + /* + * We are entering the kernel so we need to disable the protection. + * Enter critical section, disable ranges and leave critical section. + */ + call a5, __enable_kernel_ranges +#endif + /* + * Move argument for kernel function into d0, and set a5 return address + * (a5) to do_exit and return through a2 + */ + move.4 d0, d1 ; d0 = arg + move.4 a5, d3 ; a5 = do_exit + ret d2 ; call function ptr in d2 + .size kernel_thread_helper, . - kernel_thread_helper + +#ifdef CONFIG_PROTECT_KERNEL + .section .kernel_unprotected, "ax", @progbits +__enable_kernel_ranges: + atomic_lock_acquire ; Enter critical section + enable_kernel_ranges_for_current d15 + atomic_lock_release ; Leave critical section + calli a5, 0(a5) + .size __enable_kernel_ranges, . - __enable_kernel_ranges + +#endif + +/* + * The following system call intercept functions where we setup the + * input to the real system call. In all cases these are just taking + * the current sp which is pointing to pt_regs and pushing it into the + * last arg of the system call. + * + * i.e. the public definition of sys_execv is + * sys_execve( char *name, + * char **argv, + * char **envp ) + * but process.c defines it as + * sys_execve( char *name, + * char **argv, + * char **envp, + * struct pt_regs *regs ) + * + * so execve_intercept needs to populate the 4th arg with pt_regs*, + * which is the stack pointer as we know we must be coming out of + * system_call + * + * The intercept vectors are referenced by syscalltable.S + */ + +/* + * execve_intercept() + */ + .section .text.execve_intercept, "ax", @progbits + .global execve_intercept +execve_intercept: + move.4 d3, sp ; Save pt_regs address + call a3, sys_execve + + .size execve_intercept, . - execve_intercept + +/* + * vfork_intercept() + */ + .section .text.vfork_intercept, "ax", @progbits + .global vfork_intercept +vfork_intercept: + move.4 d0, sp ; Save pt_regs address + call a3, sys_vfork + + .size vfork_intercept, . - vfork_intercept + +/* + * clone_intercept() + */ + .section .text.clone_intercept, "ax", @progbits + .global clone_intercept +clone_intercept: + move.4 d2, sp ; Save pt_regs address + call a3, sys_clone + + .size clone_intercept, . - clone_intercept + +/* + * sys_sigsuspend() + */ + .section .text.sigclone_intercept, "ax", @progbits + .global sys_sigsuspend +sys_sigsuspend: + move.4 d0, sp ; Pass pointer to pt_regs in d0 + call a3, do_sigsuspend + + .size sys_sigsuspend, . - sys_sigsuspend + +/* + * sys_rt_sigsuspend() + */ + .section .text.sys_rt_sigsuspend, "ax", @progbits + .global sys_rt_sigsuspend +sys_rt_sigsuspend: + move.4 d0, sp ; Pass pointer to pt_regs in d0 + call a3, do_rt_sigsuspend + + .size sys_rt_sigsuspend, . - sys_rt_sigsuspend + +/* + * sys_rt_sigreturn() + */ + .section .text.sys_rt_sigreturn, "ax", @progbits + .global sys_rt_sigreturn +sys_rt_sigreturn: + move.4 d0, sp ; Pass pointer to pt_regs in d0 + call a3, do_rt_sigreturn + + .size sys_rt_sigreturn, . - sys_rt_sigreturn + +/* + * sys_sigaltstack() + */ + .section .text.sys_sigaltstack, "ax", @progbits + .global sys_sigaltstack +sys_sigaltstack: + move.4 d0, sp ; Pass pointer to pt_regs in d0 + call a3, do_sys_sigaltstack + + .size sys_sigaltstack, . - sys_sigaltstack |