Since ptrace facility isn't used under !MMU of UML, there is different code path to invoke processes/threads; there are no external process used, and need to properly configure some of registers (fs segment register for TLS, etc) on every context switch, etc.
Signals aren't delivered in non-ptrace syscall entry/leave so, we also need to handle pending signal by ourselves. ptrace related syscalls are not tested yet so, marked arch_has_single_step() unsupported in !MMU environment. Signed-off-by: Hajime Tazaki <[email protected]> Signed-off-by: Ricardo Koller <[email protected]> --- arch/um/include/asm/ptrace-generic.h | 2 +- arch/x86/um/nommu/Makefile | 2 +- arch/x86/um/nommu/entry_64.S | 2 ++ arch/x86/um/nommu/syscalls.h | 2 ++ arch/x86/um/nommu/syscalls_64.c | 40 ++++++++++++++++++++++++++++ arch/x86/um/syscalls_64.c | 2 +- 6 files changed, 47 insertions(+), 3 deletions(-) create mode 100644 arch/x86/um/nommu/syscalls_64.c diff --git a/arch/um/include/asm/ptrace-generic.h b/arch/um/include/asm/ptrace-generic.h index 62e9916078ec..5aa38fe6b2fb 100644 --- a/arch/um/include/asm/ptrace-generic.h +++ b/arch/um/include/asm/ptrace-generic.h @@ -14,7 +14,7 @@ struct pt_regs { struct uml_pt_regs regs; }; -#define arch_has_single_step() (1) +#define arch_has_single_step() (IS_ENABLED(CONFIG_MMU)) #define EMPTY_REGS { .regs = EMPTY_UML_PT_REGS } diff --git a/arch/x86/um/nommu/Makefile b/arch/x86/um/nommu/Makefile index ebe47d4836f4..4018d9e0aba0 100644 --- a/arch/x86/um/nommu/Makefile +++ b/arch/x86/um/nommu/Makefile @@ -5,4 +5,4 @@ else BITS := 64 endif -obj-y = do_syscall_$(BITS).o entry_$(BITS).o os-Linux/ +obj-y = do_syscall_$(BITS).o entry_$(BITS).o syscalls_$(BITS).o os-Linux/ diff --git a/arch/x86/um/nommu/entry_64.S b/arch/x86/um/nommu/entry_64.S index 485c578aae64..a58922fc81e5 100644 --- a/arch/x86/um/nommu/entry_64.S +++ b/arch/x86/um/nommu/entry_64.S @@ -86,6 +86,8 @@ END(__kernel_vsyscall) */ ENTRY(userspace) + /* set stack and pt_regs to the current task */ + call arch_set_stack_to_current /* clear direction flag to meet ABI */ cld /* align the stack for x86_64 ABI */ diff --git a/arch/x86/um/nommu/syscalls.h b/arch/x86/um/nommu/syscalls.h index a2433756b1fc..ce16bf8abd59 100644 --- a/arch/x86/um/nommu/syscalls.h +++ b/arch/x86/um/nommu/syscalls.h @@ -13,4 +13,6 @@ extern long current_top_of_stack; extern long current_ptregs; +void arch_set_stack_to_current(void); + #endif diff --git a/arch/x86/um/nommu/syscalls_64.c b/arch/x86/um/nommu/syscalls_64.c new file mode 100644 index 000000000000..3b1610280110 --- /dev/null +++ b/arch/x86/um/nommu/syscalls_64.c @@ -0,0 +1,40 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2003 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com) + * Copyright 2003 PathScale, Inc. + * + * Licensed under the GPL + */ + +#include <linux/sched.h> +#include <linux/sched/mm.h> +#include <linux/syscalls.h> +#include <linux/uaccess.h> +#include <asm/prctl.h> /* XXX This should get the constants from libc */ +#include <registers.h> +#include <os.h> +#include "syscalls.h" + +void arch_set_stack_to_current(void) +{ + current_top_of_stack = task_top_of_stack(current); + current_ptregs = (long)task_pt_regs(current); +} + +void arch_switch_to(struct task_struct *to) +{ + /* + * In !CONFIG_MMU, it doesn't ptrace thus, + * The FS_BASE registers are saved here. + */ + current_top_of_stack = task_top_of_stack(to); + current_ptregs = (long)task_pt_regs(to); + + if ((to->thread.regs.regs.gp[FS_BASE / sizeof(unsigned long)] == 0) || + (to->mm == NULL)) + return; + + /* this changes the FS on every context switch */ + arch_prctl(to, ARCH_SET_FS, + (void __user *) to->thread.regs.regs.gp[FS_BASE / sizeof(unsigned long)]); +} diff --git a/arch/x86/um/syscalls_64.c b/arch/x86/um/syscalls_64.c index 6a00a28c9cca..9684850603a2 100644 --- a/arch/x86/um/syscalls_64.c +++ b/arch/x86/um/syscalls_64.c @@ -45,7 +45,7 @@ SYSCALL_DEFINE2(arch_prctl, int, option, unsigned long, arg2) return arch_prctl(current, option, (unsigned long __user *) arg2); } -void arch_switch_to(struct task_struct *to) +__weak void arch_switch_to(struct task_struct *to) { /* * Nothing needs to be done on x86_64. -- 2.43.0
