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ARM: Thumb-2: Support Thumb-2 in undefined instruction handler

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This patch allows undef_hook's to be specified for 32-bit Thumb
instructions and also to be used for thumb kernel-side code.

32-bit Thumb instructions are specified in the form:
	((first_half << 16 ) | second_half)
which matches the layout used by the ARM ARM.

ptrace was handling 32-bit Thumb instructions by hooking the first
halfword and manually checking the second half. This method would be
broken by this patch so it is migrated to make use of the new Thumb-2
support.

Signed-off-by: Jon Medhurst <tixy@yxit.co.uk>
Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
This commit is contained in:
Jon Medhurst 2011-03-26 19:19:07 +00:00 committed by Tixy
parent 594810621d
commit 592201a9f1
3 changed files with 27 additions and 26 deletions
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8
arch/arm/include/asm/ptrace.h
View File

@ -199,6 +199,14 @@ extern unsigned long profile_pc(struct pt_regs *regs);
#define predicate(x) ((x) & 0xf0000000)
#define PREDICATE_ALWAYS 0xe0000000
/*
* True if instr is a 32-bit thumb instruction. This works if instr
* is the first or only half-word of a thumb instruction. It also works
* when instr holds all 32-bits of a wide thumb instruction if stored
* in the form (first_half<<16)|(second_half)
*/
#define is_wide_instruction(instr) ((unsigned)(instr) >= 0xe800)
/*
* kprobe-based event tracer support
*/

28
arch/arm/kernel/ptrace.c
View File

@ -228,34 +228,12 @@ static struct undef_hook thumb_break_hook = {
.fn = break_trap,
};
static int thumb2_break_trap(struct pt_regs *regs, unsigned int instr)
{
unsigned int instr2;
void __user *pc;
/* Check the second half of the instruction. */
pc = (void __user *)(instruction_pointer(regs) + 2);
if (processor_mode(regs) == SVC_MODE) {
instr2 = *(u16 *) pc;
} else {
get_user(instr2, (u16 __user *)pc);
}
if (instr2 == 0xa000) {
ptrace_break(current, regs);
return 0;
} else {
return 1;
}
}
static struct undef_hook thumb2_break_hook = {
.instr_mask = 0xffff,
.instr_val = 0xf7f0,
.instr_mask = 0xffffffff,
.instr_val = 0xf7f0a000,
.cpsr_mask = PSR_T_BIT,
.cpsr_val = PSR_T_BIT,
.fn = thumb2_break_trap,
.fn = break_trap,
};
static int __init ptrace_break_init(void)

17
arch/arm/kernel/traps.c
View File

@ -355,9 +355,24 @@ asmlinkage void __exception do_undefinstr(struct pt_regs *regs)
pc = (void __user *)instruction_pointer(regs);
if (processor_mode(regs) == SVC_MODE) {
instr = *(u32 *) pc;
#ifdef CONFIG_THUMB2_KERNEL
if (thumb_mode(regs)) {
instr = ((u16 *)pc)[0];
if (is_wide_instruction(instr)) {
instr <<= 16;
instr |= ((u16 *)pc)[1];
}
} else
#endif
instr = *(u32 *) pc;
} else if (thumb_mode(regs)) {
get_user(instr, (u16 __user *)pc);
if (is_wide_instruction(instr)) {
unsigned int instr2;
get_user(instr2, (u16 __user *)pc+1);
instr <<= 16;
instr |= instr2;
}
} else {
get_user(instr, (u32 __user *)pc);
}