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This moves the single-step support code from ptrace_64.c into a new file step.c, verbatim. This paves the way for consolidating this code between 64-bit and 32-bit versions. Signed-off-by: Roland McGrath <roland@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Roland McGrath
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Ingo Molnar
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Jan 30, 2008
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -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> | ||
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| #define LDT_SEGMENT 4 | ||
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| unsigned long convert_rip_to_linear(struct task_struct *child, struct pt_regs *regs) | ||
| { | ||
| unsigned long addr, seg; | ||
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| addr = regs->rip; | ||
| seg = regs->cs & 0xffff; | ||
|
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| /* | ||
| * 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; | ||
|
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| seg &= ~7UL; | ||
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| 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)); | ||
|
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| /* 16-bit code segment? */ | ||
| if (!((desc[1] >> 22) & 1)) | ||
| addr &= 0xffff; | ||
| addr += base; | ||
| } | ||
| mutex_unlock(&child->mm->context.lock); | ||
| } | ||
|
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| return addr; | ||
| } | ||
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| 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); | ||
|
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||
| 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; | ||
|
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| /* CHECKME: 64 65 */ | ||
|
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| /* 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; | ||
|
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| case 0x40 ... 0x4f: | ||
| if (regs->cs != __USER_CS) | ||
| /* 32-bit mode: register increment */ | ||
| return 0; | ||
| /* 64-bit mode: REX prefix */ | ||
| continue; | ||
|
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| /* CHECKME: f2, f3 */ | ||
|
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| /* | ||
| * 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; | ||
| } | ||
|
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| void user_enable_single_step(struct task_struct *child) | ||
| { | ||
| struct pt_regs *regs = task_pt_regs(child); | ||
|
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| /* | ||
| * 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); | ||
|
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| /* | ||
| * If TF was already set, don't do anything else | ||
| */ | ||
| if (regs->eflags & X86_EFLAGS_TF) | ||
| return; | ||
|
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| /* Set TF on the kernel stack.. */ | ||
| regs->eflags |= X86_EFLAGS_TF; | ||
|
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| /* | ||
| * ..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; | ||
|
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| child->ptrace |= PT_DTRACE; | ||
| } | ||
|
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| void user_disable_single_step(struct task_struct *child) | ||
| { | ||
| /* Always clear TIF_SINGLESTEP... */ | ||
| clear_tsk_thread_flag(child, TIF_SINGLESTEP); | ||
|
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| /* 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; | ||
| } | ||
| } |