Unverified Commit dcdc7a53 authored by Patrick Stählin's avatar Patrick Stählin Committed by Palmer Dabbelt
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RISC-V: Implement ptrace regs and stack API 



Needed for kprobes support. Copied and adapted from arm64 code.

Guo Ren fixup pt_regs type for linux-5.8-rc1.

Signed-off-by: default avatarPatrick Stählin <me@packi.ch>
Signed-off-by: default avatarGuo Ren <guoren@linux.alibaba.com>
Reviewed-by: default avatarPekka Enberg <penberg@kernel.org>
Reviewed-by: default avatarZong Li <zong.li@sifive.com>
Reviewed-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: default avatarPalmer Dabbelt <palmerdabbelt@google.com>
parent 46ad48e8

arch/riscv/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -75,6 +75,7 @@ config RISCV 
	select HAVE_PERF_EVENTS

	select HAVE_PERF_REGS

	select HAVE_PERF_USER_STACK_DUMP

	select HAVE_REGS_AND_STACK_ACCESS_API

	select HAVE_STACKPROTECTOR

	select HAVE_SYSCALL_TRACEPOINTS

	select IRQ_DOMAIN

arch/riscv/include/asm/ptrace.h

+29 −0
Original line number Diff line number Diff line
@@ -8,6 +8,7 @@ 


#include <uapi/asm/ptrace.h>

#include <asm/csr.h>

#include <linux/compiler.h>



#ifndef __ASSEMBLY__
@@ -60,6 +61,7 @@ struct pt_regs { 


#define user_mode(regs) (((regs)->status & SR_PP) == 0)



#define MAX_REG_OFFSET offsetof(struct pt_regs, orig_a0)



/* Helpers for working with the instruction pointer */

static inline unsigned long instruction_pointer(struct pt_regs *regs)
@@ -85,6 +87,12 @@ static inline void user_stack_pointer_set(struct pt_regs *regs, 
	regs->sp =  val;

}



/* Valid only for Kernel mode traps. */

static inline unsigned long kernel_stack_pointer(struct pt_regs *regs)

{

	return regs->sp;

}



/* Helpers for working with the frame pointer */

static inline unsigned long frame_pointer(struct pt_regs *regs)

{
@@ -101,6 +109,27 @@ static inline unsigned long regs_return_value(struct pt_regs *regs) 
	return regs->a0;

}



extern int regs_query_register_offset(const char *name);

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 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);

}

#endif /* __ASSEMBLY__ */



#endif /* _ASM_RISCV_PTRACE_H */

arch/riscv/kernel/ptrace.c

+99 −0
Original line number Diff line number Diff line
@@ -114,6 +114,105 @@ const struct user_regset_view *task_user_regset_view(struct task_struct *task) 
	return &riscv_user_native_view;

}



struct pt_regs_offset {

	const char *name;

	int offset;

};



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

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



static const struct pt_regs_offset regoffset_table[] = {

	REG_OFFSET_NAME(epc),

	REG_OFFSET_NAME(ra),

	REG_OFFSET_NAME(sp),

	REG_OFFSET_NAME(gp),

	REG_OFFSET_NAME(tp),

	REG_OFFSET_NAME(t0),

	REG_OFFSET_NAME(t1),

	REG_OFFSET_NAME(t2),

	REG_OFFSET_NAME(s0),

	REG_OFFSET_NAME(s1),

	REG_OFFSET_NAME(a0),

	REG_OFFSET_NAME(a1),

	REG_OFFSET_NAME(a2),

	REG_OFFSET_NAME(a3),

	REG_OFFSET_NAME(a4),

	REG_OFFSET_NAME(a5),

	REG_OFFSET_NAME(a6),

	REG_OFFSET_NAME(a7),

	REG_OFFSET_NAME(s2),

	REG_OFFSET_NAME(s3),

	REG_OFFSET_NAME(s4),

	REG_OFFSET_NAME(s5),

	REG_OFFSET_NAME(s6),

	REG_OFFSET_NAME(s7),

	REG_OFFSET_NAME(s8),

	REG_OFFSET_NAME(s9),

	REG_OFFSET_NAME(s10),

	REG_OFFSET_NAME(s11),

	REG_OFFSET_NAME(t3),

	REG_OFFSET_NAME(t4),

	REG_OFFSET_NAME(t5),

	REG_OFFSET_NAME(t6),

	REG_OFFSET_NAME(status),

	REG_OFFSET_NAME(badaddr),

	REG_OFFSET_NAME(cause),

	REG_OFFSET_NAME(orig_a0),

	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_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.

 */

static 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;

}



void ptrace_disable(struct task_struct *child)

{

	clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);