Introduces a few of the system call inspection functions for ARM. The current motivation is checkpoint restart, but the general interface requirements are met, making it possible for a debugger or tracer to obtain information about the system call status of another process. The patch is in part based on the following proposal from Roland McGrath: https://patchwork.kernel.org/patch/32101/ Compared to other architectures, the code to implement syscall_get_nr is somewhat comprehensive. However, it's a result of no globally stored location for the system call number and the complexity of the ARM ABI with multiple versions. Changelog[v2]: - Get the system call number by inspecting the process instead of storing the system call number globally on entry to each system call. Cc: Roland McGrath <roland@xxxxxxxxxx> Signed-off-by: Christoffer Dall <christofferdall@xxxxxxxxxxxxxxxxxx> Acked-by: Oren Laadan <orenl@xxxxxxxxxxxxxxx> --- arch/arm/include/asm/syscall.h | 133 ++++++++++++++++++++++++++++++++++++++++ 1 files changed, 133 insertions(+), 0 deletions(-) create mode 100644 arch/arm/include/asm/syscall.h diff --git a/arch/arm/include/asm/syscall.h b/arch/arm/include/asm/syscall.h new file mode 100644 index 0000000..49cb10e --- /dev/null +++ b/arch/arm/include/asm/syscall.h @@ -0,0 +1,133 @@ +/* + * syscalls.h - Linux syscall interfaces for ARM + * + * Copyright (c) 2010 Christoffer Dall + * + * This file is released under the GPLv2. + * See the file COPYING for more details. + */ + +#ifndef _ASM_ARM_SYSCALLS_H +#define _ASM_ARM_SYSCALLS_H + +#include <linux/highmem.h> +#include <linux/pagemap.h> +#include <linux/memory.h> +#include <asm/unistd.h> + +static inline int get_swi_instruction(struct task_struct *task, + struct pt_regs *regs, + unsigned long *instr) +{ + struct page *page = NULL; + unsigned long instr_addr; + unsigned long *ptr; + int ret; + + instr_addr = regs->ARM_pc - 4; + + down_read(&task->mm->mmap_sem); + ret = get_user_pages(task, task->mm, instr_addr, + 1, 0, 0, &page, NULL); + up_read(&task->mm->mmap_sem); + + if (ret < 0) + return ret; + + ptr = (unsigned long *)kmap_atomic(page, KM_USER1); + memcpy(instr, + ptr + (instr_addr >> PAGE_SHIFT), + sizeof(unsigned long)); + kunmap_atomic(ptr, KM_USER1); + + page_cache_release(page); + + return 0; +} + +/* + * This function essentially duplicates the logic from vector_swi in + * arch/arm/kernel/entry-common.S. However, that code is in the + * critical path for system calls and is hard to factor out without + * compromising performance. + */ +static inline int __syscall_get_nr(struct task_struct *task, + struct pt_regs *regs) +{ + int ret; + int scno; + unsigned long instr; + bool config_oabi = false; + bool config_aeabi = false; + bool config_arm_thumb = false; + bool config_cpu_endian_be8 = false; + +#ifdef CONFIG_OABI_COMPAT + config_oabi = true; +#endif +#ifdef CONFIG_AEABI + config_aeabi = true; +#endif +#ifdef CONFIG_ARM_THUMB + config_arm_thumb = true; +#endif +#ifdef CONFIG_CPU_ENDIAN_BE8 + config_cpu_endian_be8 = true; +#endif +#ifdef CONFIG_CPU_ARM710 + return -1; +#endif + + if (config_aeabi && !config_oabi) { + /* Pure EABI */ + return regs->ARM_r7; + } else if (config_oabi) { + if (config_arm_thumb && (regs->ARM_cpsr & PSR_T_BIT)) + return -1; + + ret = get_swi_instruction(task, regs, &instr); + if (ret < 0) + return -1; + + if (config_cpu_endian_be8) + asm ("rev %[out], %[in]": [out] "=r" (instr): + [in] "r" (instr)); + + if ((instr & 0x00ffffff) == 0) + return regs->ARM_r7; /* EABI call */ + else + return (instr & 0x00ffffff) | __NR_OABI_SYSCALL_BASE; + } else { + /* Legacy ABI only */ + if (config_arm_thumb && (regs->ARM_cpsr & PSR_T_BIT)) { + /* Thumb mode ABI */ + scno = regs->ARM_r7 + __NR_SYSCALL_BASE; + } else { + ret = get_swi_instruction(task, regs, &instr); + if (ret < 0) + return -1; + scno = instr; + } + return scno & 0x00ffffff; + } +} + +static inline int syscall_get_nr(struct task_struct *task, + struct pt_regs *regs) +{ + return __syscall_get_nr(task, regs); +} + +static inline long syscall_get_return_value(struct task_struct *task, + struct pt_regs *regs) +{ + return regs->ARM_r0; +} + +static inline long syscall_get_error(struct task_struct *task, + struct pt_regs *regs) +{ + return regs->ARM_r0; +} + +#endif /* _ASM_ARM_SYSCALLS_H */ -- 1.5.6.5 _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/containers
