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425fc47adb
PTRACE_SINGLESTEP is a ptrace request designed to offer single-stepping support to userspace when the underlying architecture has hardware support for this operation. On ARM, we set arch_has_single_step() to 1 and attempt to emulate hardware single-stepping by disassembling the current instruction to determine the next pc and placing a software breakpoint on that location. Unfortunately this has the following problems: 1.) Only a subset of ARMv7 instructions are supported 2.) Thumb-2 is unsupported 3.) The code is not SMP safe We could try to fix this code, but it turns out that because of the above issues it is rarely used in practice. GDB, for example, uses PTRACE_POKETEXT and PTRACE_PEEKTEXT to manage breakpoints itself and does not require any kernel assistance. This patch removes the single-step emulation code from ptrace meaning that the PTRACE_SINGLESTEP request will return -EIO on ARM. Portable code must check the return value from a ptrace call and handle the failure gracefully. Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
53 lines
1.2 KiB
C
53 lines
1.2 KiB
C
#ifndef _ASMARM_TRAP_H
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#define _ASMARM_TRAP_H
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#include <linux/list.h>
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struct undef_hook {
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struct list_head node;
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u32 instr_mask;
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u32 instr_val;
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u32 cpsr_mask;
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u32 cpsr_val;
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int (*fn)(struct pt_regs *regs, unsigned int instr);
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};
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void register_undef_hook(struct undef_hook *hook);
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void unregister_undef_hook(struct undef_hook *hook);
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER
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static inline int __in_irqentry_text(unsigned long ptr)
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{
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extern char __irqentry_text_start[];
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extern char __irqentry_text_end[];
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return ptr >= (unsigned long)&__irqentry_text_start &&
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ptr < (unsigned long)&__irqentry_text_end;
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}
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#else
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static inline int __in_irqentry_text(unsigned long ptr)
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{
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return 0;
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}
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#endif
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static inline int in_exception_text(unsigned long ptr)
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{
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extern char __exception_text_start[];
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extern char __exception_text_end[];
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int in;
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in = ptr >= (unsigned long)&__exception_text_start &&
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ptr < (unsigned long)&__exception_text_end;
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return in ? : __in_irqentry_text(ptr);
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}
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extern void __init early_trap_init(void);
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extern void dump_backtrace_entry(unsigned long where, unsigned long from, unsigned long frame);
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extern void ptrace_break(struct task_struct *tsk, struct pt_regs *regs);
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extern void *vectors_page;
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#endif
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