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Commit e513f8bf authored by Will Deacon's avatar Will Deacon Committed by Russell King
Browse files

ARM: 6199/1: Add kprobe-based event tracer 



This patch enables the HAVE_REGS_AND_STACK_ACCESS_API option
for ARM which is required by the kprobe events tracer. Code based
on the PowerPC port.

Cc: Jean Pihet <jpihet@mvista.com>
Tested-by: default avatarJamie Iles <jamie.iles@picochip.com>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent eb668c6d

arch/arm/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -24,6 +24,7 @@ config ARM 
	select HAVE_KERNEL_LZMA

	select HAVE_PERF_EVENTS

	select PERF_USE_VMALLOC

	select HAVE_REGS_AND_STACK_ACCESS_API

	help

	  The ARM series is a line of low-power-consumption RISC chip designs

	  licensed by ARM Ltd and targeted at embedded applications and

arch/arm/include/asm/ptrace.h

+36 −0
Original line number Diff line number Diff line
@@ -184,6 +184,42 @@ extern unsigned long profile_pc(struct pt_regs *regs); 
#define predicate(x)		((x) & 0xf0000000)

#define PREDICATE_ALWAYS	0xe0000000



/*

 * kprobe-based event tracer support

 */

#include <linux/stddef.h>

#include <linux/types.h>

#define MAX_REG_OFFSET (offsetof(struct pt_regs, ARM_ORIG_r0))



extern int regs_query_register_offset(const char *name);

extern const char *regs_query_register_name(unsigned int offset);

extern bool regs_within_kernel_stack(struct pt_regs *regs, unsigned long addr);

extern unsigned long regs_get_kernel_stack_nth(struct pt_regs *regs,

					       unsigned int n);



/**

 * regs_get_register() - get register value from its offset

 * @regs:	   pt_regs from which register value is gotten

 * @offset:    offset number of the register.

 *

 * regs_get_register returns the value of a register whose offset from @regs.

 * The @offset is the offset of the register in struct pt_regs.

 * If @offset is bigger than MAX_REG_OFFSET, this returns 0.

 */

static inline unsigned long regs_get_register(struct pt_regs *regs,

					      unsigned int offset)

{

	if (unlikely(offset > MAX_REG_OFFSET))

		return 0;

	return *(unsigned long *)((unsigned long)regs + offset);

}



/* Valid only for Kernel mode traps. */

static inline unsigned long kernel_stack_pointer(struct pt_regs *regs)

{

	return regs->ARM_sp;

}



#endif /* __KERNEL__ */



#endif /* __ASSEMBLY__ */

arch/arm/kernel/ptrace.c

+96 −0
Original line number Diff line number Diff line
@@ -52,6 +52,102 @@ 
#define BREAKINST_THUMB	0xde01

#endif



struct pt_regs_offset {

	const char *name;

	int offset;

};



#define REG_OFFSET_NAME(r) \

	{.name = #r, .offset = offsetof(struct pt_regs, ARM_##r)}

#define REG_OFFSET_END {.name = NULL, .offset = 0}



static const struct pt_regs_offset regoffset_table[] = {

	REG_OFFSET_NAME(r0),

	REG_OFFSET_NAME(r1),

	REG_OFFSET_NAME(r2),

	REG_OFFSET_NAME(r3),

	REG_OFFSET_NAME(r4),

	REG_OFFSET_NAME(r5),

	REG_OFFSET_NAME(r6),

	REG_OFFSET_NAME(r7),

	REG_OFFSET_NAME(r8),

	REG_OFFSET_NAME(r9),

	REG_OFFSET_NAME(r10),

	REG_OFFSET_NAME(fp),

	REG_OFFSET_NAME(ip),

	REG_OFFSET_NAME(sp),

	REG_OFFSET_NAME(lr),

	REG_OFFSET_NAME(pc),

	REG_OFFSET_NAME(cpsr),

	REG_OFFSET_NAME(ORIG_r0),

	REG_OFFSET_END,

};



/**

 * regs_query_register_offset() - query register offset from its name

 * @name:	the name of a register

 *

 * regs_query_register_offset() returns the offset of a register in struct

 * pt_regs from its name. If the name is invalid, this returns -EINVAL;

 */

int regs_query_register_offset(const char *name)

{

	const struct pt_regs_offset *roff;

	for (roff = regoffset_table; roff->name != NULL; roff++)

		if (!strcmp(roff->name, name))

			return roff->offset;

	return -EINVAL;

}



/**

 * regs_query_register_name() - query register name from its offset

 * @offset:	the offset of a register in struct pt_regs.

 *

 * regs_query_register_name() returns the name of a register from its

 * offset in struct pt_regs. If the @offset is invalid, this returns NULL;

 */

const char *regs_query_register_name(unsigned int offset)

{

	const struct pt_regs_offset *roff;

	for (roff = regoffset_table; roff->name != NULL; roff++)

		if (roff->offset == offset)

			return roff->name;

	return NULL;

}



/**

 * regs_within_kernel_stack() - check the address in the stack

 * @regs:      pt_regs which contains kernel stack pointer.

 * @addr:      address which is checked.

 *

 * regs_within_kernel_stack() checks @addr is within the kernel stack page(s).

 * If @addr is within the kernel stack, it returns true. If not, returns false.

 */

bool regs_within_kernel_stack(struct pt_regs *regs, unsigned long addr)

{

	return ((addr & ~(THREAD_SIZE - 1))  ==

		(kernel_stack_pointer(regs) & ~(THREAD_SIZE - 1)));

}



/**

 * regs_get_kernel_stack_nth() - get Nth entry of the stack

 * @regs:	pt_regs which contains kernel stack pointer.

 * @n:		stack entry number.

 *

 * regs_get_kernel_stack_nth() returns @n th entry of the kernel stack which

 * is specified by @regs. If the @n th entry is NOT in the kernel stack,

 * this returns 0.

 */

unsigned long regs_get_kernel_stack_nth(struct pt_regs *regs, unsigned int n)

{

	unsigned long *addr = (unsigned long *)kernel_stack_pointer(regs);

	addr += n;

	if (regs_within_kernel_stack(regs, (unsigned long)addr))

		return *addr;

	else

		return 0;

}



/*

 * this routine will get a word off of the processes privileged stack.

 * the offset is how far from the base addr as stored in the THREAD.