diff options
| -rw-r--r-- | arch/x86/kernel/Makefile_64 | 2 | ||||
| -rw-r--r-- | arch/x86/kernel/ptrace_64.c | 134 | ||||
| -rw-r--r-- | arch/x86/kernel/step.c | 140 |
3 files changed, 142 insertions, 134 deletions
diff --git a/arch/x86/kernel/Makefile_64 b/arch/x86/kernel/Makefile_64 index e1ba82e582a8..d908f0175e76 100644 --- a/arch/x86/kernel/Makefile_64 +++ b/arch/x86/kernel/Makefile_64 @@ -13,6 +13,8 @@ obj-y := process_64.o signal_64.o entry_64.o traps_64.o irq_64.o \ pci-dma_64.o pci-nommu_64.o alternative.o hpet.o tsc_64.o bugs_64.o \ i8253.o io_delay.o rtc.o +obj-y += step.o + obj-$(CONFIG_IA32_EMULATION) += tls.o obj-$(CONFIG_STACKTRACE) += stacktrace.o obj-y += cpu/ diff --git a/arch/x86/kernel/ptrace_64.c b/arch/x86/kernel/ptrace_64.c index 7373a99facf3..4abfbced9b26 100644 --- a/arch/x86/kernel/ptrace_64.c +++ b/arch/x86/kernel/ptrace_64.c @@ -80,140 +80,6 @@ static inline long put_stack_long(struct task_struct *task, int offset, return 0; } -#define LDT_SEGMENT 4 - -unsigned long convert_rip_to_linear(struct task_struct *child, struct pt_regs *regs) -{ - unsigned long addr, seg; - - addr = regs->rip; - seg = regs->cs & 0xffff; - - /* - * We'll assume that the code segments in the GDT - * are all zero-based. That is largely true: the - * TLS segments are used for data, and the PNPBIOS - * and APM bios ones we just ignore here. - */ - if (seg & LDT_SEGMENT) { - u32 *desc; - unsigned long base; - - seg &= ~7UL; - - mutex_lock(&child->mm->context.lock); - if (unlikely((seg >> 3) >= child->mm->context.size)) - addr = -1L; /* bogus selector, access would fault */ - else { - desc = child->mm->context.ldt + seg; - base = ((desc[0] >> 16) | - ((desc[1] & 0xff) << 16) | - (desc[1] & 0xff000000)); - - /* 16-bit code segment? */ - if (!((desc[1] >> 22) & 1)) - addr &= 0xffff; - addr += base; - } - mutex_unlock(&child->mm->context.lock); - } - - return addr; -} - -static int is_setting_trap_flag(struct task_struct *child, struct pt_regs *regs) -{ - int i, copied; - unsigned char opcode[15]; - unsigned long addr = convert_rip_to_linear(child, regs); - - copied = access_process_vm(child, addr, opcode, sizeof(opcode), 0); - for (i = 0; i < copied; i++) { - switch (opcode[i]) { - /* popf and iret */ - case 0x9d: case 0xcf: - return 1; - - /* CHECKME: 64 65 */ - - /* opcode and address size prefixes */ - case 0x66: case 0x67: - continue; - /* irrelevant prefixes (segment overrides and repeats) */ - case 0x26: case 0x2e: - case 0x36: case 0x3e: - case 0x64: case 0x65: - case 0xf2: case 0xf3: - continue; - - case 0x40 ... 0x4f: - if (regs->cs != __USER_CS) - /* 32-bit mode: register increment */ - return 0; - /* 64-bit mode: REX prefix */ - continue; - - /* CHECKME: f2, f3 */ - - /* - * pushf: NOTE! We should probably not let - * the user see the TF bit being set. But - * it's more pain than it's worth to avoid - * it, and a debugger could emulate this - * all in user space if it _really_ cares. - */ - case 0x9c: - default: - return 0; - } - } - return 0; -} - -void user_enable_single_step(struct task_struct *child) -{ - struct pt_regs *regs = task_pt_regs(child); - - /* - * Always set TIF_SINGLESTEP - this guarantees that - * we single-step system calls etc.. This will also - * cause us to set TF when returning to user mode. - */ - set_tsk_thread_flag(child, TIF_SINGLESTEP); - - /* - * If TF was already set, don't do anything else - */ - if (regs->eflags & X86_EFLAGS_TF) - return; - - /* Set TF on the kernel stack.. */ - regs->eflags |= X86_EFLAGS_TF; - - /* - * ..but if TF is changed by the instruction we will trace, - * don't mark it as being "us" that set it, so that we - * won't clear it by hand later. - */ - if (is_setting_trap_flag(child, regs)) - return; - - child->ptrace |= PT_DTRACE; -} - -void user_disable_single_step(struct task_struct *child) -{ - /* Always clear TIF_SINGLESTEP... */ - clear_tsk_thread_flag(child, TIF_SINGLESTEP); - - /* But touch TF only if it was set by us.. */ - if (child->ptrace & PT_DTRACE) { - struct pt_regs *regs = task_pt_regs(child); - regs->eflags &= ~X86_EFLAGS_TF; - child->ptrace &= ~PT_DTRACE; - } -} - /* * Called by kernel/ptrace.c when detaching.. * diff --git a/arch/x86/kernel/step.c b/arch/x86/kernel/step.c new file mode 100644 index 000000000000..cb3c8bc2939a --- /dev/null +++ b/arch/x86/kernel/step.c @@ -0,0 +1,140 @@ +/* + * x86 single-step support code, common to 32-bit and 64-bit. + */ +#include <linux/sched.h> +#include <linux/mm.h> +#include <linux/ptrace.h> + +#define LDT_SEGMENT 4 + +unsigned long convert_rip_to_linear(struct task_struct *child, struct pt_regs *regs) +{ + unsigned long addr, seg; + + addr = regs->rip; + seg = regs->cs & 0xffff; + + /* + * We'll assume that the code segments in the GDT + * are all zero-based. That is largely true: the + * TLS segments are used for data, and the PNPBIOS + * and APM bios ones we just ignore here. + */ + if (seg & LDT_SEGMENT) { + u32 *desc; + unsigned long base; + + seg &= ~7UL; + + mutex_lock(&child->mm->context.lock); + if (unlikely((seg >> 3) >= child->mm->context.size)) + addr = -1L; /* bogus selector, access would fault */ + else { + desc = child->mm->context.ldt + seg; + base = ((desc[0] >> 16) | + ((desc[1] & 0xff) << 16) | + (desc[1] & 0xff000000)); + + /* 16-bit code segment? */ + if (!((desc[1] >> 22) & 1)) + addr &= 0xffff; + addr += base; + } + mutex_unlock(&child->mm->context.lock); + } + + return addr; +} + +static int is_setting_trap_flag(struct task_struct *child, struct pt_regs *regs) +{ + int i, copied; + unsigned char opcode[15]; + unsigned long addr = convert_rip_to_linear(child, regs); + + copied = access_process_vm(child, addr, opcode, sizeof(opcode), 0); + for (i = 0; i < copied; i++) { + switch (opcode[i]) { + /* popf and iret */ + case 0x9d: case 0xcf: + return 1; + + /* CHECKME: 64 65 */ + + /* opcode and address size prefixes */ + case 0x66: case 0x67: + continue; + /* irrelevant prefixes (segment overrides and repeats) */ + case 0x26: case 0x2e: + case 0x36: case 0x3e: + case 0x64: case 0x65: + case 0xf2: case 0xf3: + continue; + + case 0x40 ... 0x4f: + if (regs->cs != __USER_CS) + /* 32-bit mode: register increment */ + return 0; + /* 64-bit mode: REX prefix */ + continue; + + /* CHECKME: f2, f3 */ + + /* + * pushf: NOTE! We should probably not let + * the user see the TF bit being set. But + * it's more pain than it's worth to avoid + * it, and a debugger could emulate this + * all in user space if it _really_ cares. + */ + case 0x9c: + default: + return 0; + } + } + return 0; +} + +void user_enable_single_step(struct task_struct *child) +{ + struct pt_regs *regs = task_pt_regs(child); + + /* + * Always set TIF_SINGLESTEP - this guarantees that + * we single-step system calls etc.. This will also + * cause us to set TF when returning to user mode. + */ + set_tsk_thread_flag(child, TIF_SINGLESTEP); + + /* + * If TF was already set, don't do anything else + */ + if (regs->eflags & X86_EFLAGS_TF) + return; + + /* Set TF on the kernel stack.. */ + regs->eflags |= X86_EFLAGS_TF; + + /* + * ..but if TF is changed by the instruction we will trace, + * don't mark it as being "us" that set it, so that we + * won't clear it by hand later. + */ + if (is_setting_trap_flag(child, regs)) + return; + + child->ptrace |= PT_DTRACE; +} + +void user_disable_single_step(struct task_struct *child) +{ + /* Always clear TIF_SINGLESTEP... */ + clear_tsk_thread_flag(child, TIF_SINGLESTEP); + + /* But touch TF only if it was set by us.. */ + if (child->ptrace & PT_DTRACE) { + struct pt_regs *regs = task_pt_regs(child); + regs->eflags &= ~X86_EFLAGS_TF; + child->ptrace &= ~PT_DTRACE; + } +} |