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: Patrick Stählin <me@packi.ch>
Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Reviewed-by: Pekka Enberg <penberg@kernel.org>
Reviewed-by: Zong Li <zong.li@sifive.com>
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
This commit is contained in:
Patrick Stählin 2020-12-17 16:01:37 +00:00 committed by Palmer Dabbelt
parent 46ad48e8a2
commit dcdc7a53a8
No known key found for this signature in database
GPG Key ID: 2E1319F35FBB1889
3 changed files with 129 additions and 0 deletions

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@ -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

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@ -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 */

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@ -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);