xref: /openbmc/linux/arch/x86/include/asm/ptrace.h (revision 9144f784f852f9a125cabe9927b986d909bfa439)

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_X86_PTRACE_H
#define _ASM_X86_PTRACE_H

#include <asm/segment.h>
#include <asm/page_types.h>
#include <uapi/asm/ptrace.h>

#ifndef __ASSEMBLY__
#ifdef __i386__

struct pt_regs {
	/*
	 * NB: 32-bit x86 CPUs are inconsistent as what happens in the
	 * following cases (where %seg represents a segment register):
	 *
	 * - pushl %seg: some do a 16-bit write and leave the high
	 *   bits alone
	 * - movl %seg, [mem]: some do a 16-bit write despite the movl
	 * - IDT entry: some (e.g. 486) will leave the high bits of CS
	 *   and (if applicable) SS undefined.
	 *
	 * Fortunately, x86-32 doesn't read the high bits on POP or IRET,
	 * so we can just treat all of the segment registers as 16-bit
	 * values.
	 */
	unsigned long bx;
	unsigned long cx;
	unsigned long dx;
	unsigned long si;
	unsigned long di;
	unsigned long bp;
	unsigned long ax;
	unsigned short ds;
	unsigned short __dsh;
	unsigned short es;
	unsigned short __esh;
	unsigned short fs;
	unsigned short __fsh;
	/*
	 * On interrupt, gs and __gsh store the vector number.  They never
	 * store gs any more.
	 */
	unsigned short gs;
	unsigned short __gsh;
	/* On interrupt, this is the error code. */
	unsigned long orig_ax;
	unsigned long ip;
	unsigned short cs;
	unsigned short __csh;
	unsigned long flags;
	unsigned long sp;
	unsigned short ss;
	unsigned short __ssh;
};

#else /* __i386__ */

struct fred_cs {
		/* CS selector */
	u64	cs	: 16,
		/* Stack level at event time */
		sl	:  2,
		/* IBT in WAIT_FOR_ENDBRANCH state */
		wfe	:  1,
			: 45;
};

struct fred_ss {
		/* SS selector */
	u64	ss	: 16,
		/* STI state */
		sti	:  1,
		/* Set if syscall, sysenter or INT n */
		swevent	:  1,
		/* Event is NMI type */
		nmi	:  1,
			: 13,
		/* Event vector */
		vector	:  8,
			:  8,
		/* Event type */
		type	:  4,
			:  4,
		/* Event was incident to enclave execution */
		enclave	:  1,
		/* CPU was in long mode */
		lm	:  1,
		/*
		 * Nested exception during FRED delivery, not set
		 * for #DF.
		 */
		nested	:  1,
			:  1,
		/*
		 * The length of the instruction causing the event.
		 * Only set for INTO, INT1, INT3, INT n, SYSCALL
		 * and SYSENTER.  0 otherwise.
		 */
		insnlen	:  4;
};

struct pt_regs {
	/*
	 * C ABI says these regs are callee-preserved. They aren't saved on
	 * kernel entry unless syscall needs a complete, fully filled
	 * "struct pt_regs".
	 */
	unsigned long r15;
	unsigned long r14;
	unsigned long r13;
	unsigned long r12;
	unsigned long bp;
	unsigned long bx;

	/* These regs are callee-clobbered. Always saved on kernel entry. */
	unsigned long r11;
	unsigned long r10;
	unsigned long r9;
	unsigned long r8;
	unsigned long ax;
	unsigned long cx;
	unsigned long dx;
	unsigned long si;
	unsigned long di;

	/*
	 * orig_ax is used on entry for:
	 * - the syscall number (syscall, sysenter, int80)
	 * - error_code stored by the CPU on traps and exceptions
	 * - the interrupt number for device interrupts
	 *
	 * A FRED stack frame starts here:
	 *   1) It _always_ includes an error code;
	 *
	 *   2) The return frame for ERET[US] starts here, but
	 *      the content of orig_ax is ignored.
	 */
	unsigned long orig_ax;

	/* The IRETQ return frame starts here */
	unsigned long ip;

	union {
		/* CS selector */
		u16		cs;
		/* The extended 64-bit data slot containing CS */
		u64		csx;
		/* The FRED CS extension */
		struct fred_cs	fred_cs;
	};

	unsigned long flags;
	unsigned long sp;

	union {
		/* SS selector */
		u16		ss;
		/* The extended 64-bit data slot containing SS */
		u64		ssx;
		/* The FRED SS extension */
		struct fred_ss	fred_ss;
	};

	/*
	 * Top of stack on IDT systems, while FRED systems have extra fields
	 * defined above for storing exception related information, e.g. CR2 or
	 * DR6.
	 */
};

#endif /* !__i386__ */

#ifdef CONFIG_PARAVIRT
#include <asm/paravirt_types.h>
#endif

#include <asm/proto.h>

struct cpuinfo_x86;
struct task_struct;

extern unsigned long profile_pc(struct pt_regs *regs);

extern unsigned long
convert_ip_to_linear(struct task_struct *child, struct pt_regs *regs);
extern void send_sigtrap(struct pt_regs *regs, int error_code, int si_code);


static inline unsigned long regs_return_value(struct pt_regs *regs)
{
	return regs->ax;
}

static inline void regs_set_return_value(struct pt_regs *regs, unsigned long rc)
{
	regs->ax = rc;
}

/*
 * user_mode(regs) determines whether a register set came from user
 * mode.  On x86_32, this is true if V8086 mode was enabled OR if the
 * register set was from protected mode with RPL-3 CS value.  This
 * tricky test checks that with one comparison.
 *
 * On x86_64, vm86 mode is mercifully nonexistent, and we don't need
 * the extra check.
 */
static __always_inline int user_mode(struct pt_regs *regs)
{
#ifdef CONFIG_X86_32
	return ((regs->cs & SEGMENT_RPL_MASK) | (regs->flags & X86_VM_MASK)) >= USER_RPL;
#else
	return !!(regs->cs & 3);
#endif
}

static __always_inline int v8086_mode(struct pt_regs *regs)
{
#ifdef CONFIG_X86_32
	return (regs->flags & X86_VM_MASK);
#else
	return 0;	/* No V86 mode support in long mode */
#endif
}

static inline bool user_64bit_mode(struct pt_regs *regs)
{
#ifdef CONFIG_X86_64
#ifndef CONFIG_PARAVIRT_XXL
	/*
	 * On non-paravirt systems, this is the only long mode CPL 3
	 * selector.  We do not allow long mode selectors in the LDT.
	 */
	return regs->cs == __USER_CS;
#else
	/* Headers are too twisted for this to go in paravirt.h. */
	return regs->cs == __USER_CS || regs->cs == pv_info.extra_user_64bit_cs;
#endif
#else /* !CONFIG_X86_64 */
	return false;
#endif
}

/*
 * Determine whether the register set came from any context that is running in
 * 64-bit mode.
 */
static inline bool any_64bit_mode(struct pt_regs *regs)
{
#ifdef CONFIG_X86_64
	return !user_mode(regs) || user_64bit_mode(regs);
#else
	return false;
#endif
}

#ifdef CONFIG_X86_64
#define current_user_stack_pointer()	current_pt_regs()->sp
#define compat_user_stack_pointer()	current_pt_regs()->sp

static __always_inline bool ip_within_syscall_gap(struct pt_regs *regs)
{
	bool ret = (regs->ip >= (unsigned long)entry_SYSCALL_64 &&
		    regs->ip <  (unsigned long)entry_SYSCALL_64_safe_stack);

	ret = ret || (regs->ip >= (unsigned long)entry_SYSRETQ_unsafe_stack &&
		      regs->ip <  (unsigned long)entry_SYSRETQ_end);
#ifdef CONFIG_IA32_EMULATION
	ret = ret || (regs->ip >= (unsigned long)entry_SYSCALL_compat &&
		      regs->ip <  (unsigned long)entry_SYSCALL_compat_safe_stack);
	ret = ret || (regs->ip >= (unsigned long)entry_SYSRETL_compat_unsafe_stack &&
		      regs->ip <  (unsigned long)entry_SYSRETL_compat_end);
#endif

	return ret;
}
#endif

static inline unsigned long kernel_stack_pointer(struct pt_regs *regs)
{
	return regs->sp;
}

static inline unsigned long instruction_pointer(struct pt_regs *regs)
{
	return regs->ip;
}

static inline void instruction_pointer_set(struct pt_regs *regs,
		unsigned long val)
{
	regs->ip = val;
}

static inline unsigned long frame_pointer(struct pt_regs *regs)
{
	return regs->bp;
}

static inline unsigned long user_stack_pointer(struct pt_regs *regs)
{
	return regs->sp;
}

static inline void user_stack_pointer_set(struct pt_regs *regs,
		unsigned long val)
{
	regs->sp = val;
}

static __always_inline bool regs_irqs_disabled(struct pt_regs *regs)
{
	return !(regs->flags & X86_EFLAGS_IF);
}

/* Query offset/name of register from its name/offset */
extern int regs_query_register_offset(const char *name);
extern const char *regs_query_register_name(unsigned int offset);
#define MAX_REG_OFFSET (offsetof(struct pt_regs, ss))

/**
 * 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. The @offset is the
 * offset of the register in struct pt_regs address which specified by @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;
#ifdef CONFIG_X86_32
	/* The selector fields are 16-bit. */
	if (offset == offsetof(struct pt_regs, cs) ||
	    offset == offsetof(struct pt_regs, ss) ||
	    offset == offsetof(struct pt_regs, ds) ||
	    offset == offsetof(struct pt_regs, es) ||
	    offset == offsetof(struct pt_regs, fs) ||
	    offset == offsetof(struct pt_regs, gs)) {
		return *(u16 *)((unsigned long)regs + offset);

	}
#endif
	return *(unsigned long *)((unsigned long)regs + offset);
}

/**
 * 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 inline int regs_within_kernel_stack(struct pt_regs *regs,
					   unsigned long addr)
{
	return ((addr & ~(THREAD_SIZE - 1)) == (regs->sp & ~(THREAD_SIZE - 1)));
}

/**
 * regs_get_kernel_stack_nth_addr() - get the address of the Nth entry on stack
 * @regs:	pt_regs which contains kernel stack pointer.
 * @n:		stack entry number.
 *
 * regs_get_kernel_stack_nth() returns the address of the @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 NULL.
 */
static inline unsigned long *regs_get_kernel_stack_nth_addr(struct pt_regs *regs, unsigned int n)
{
	unsigned long *addr = (unsigned long *)regs->sp;

	addr += n;
	if (regs_within_kernel_stack(regs, (unsigned long)addr))
		return addr;
	else
		return NULL;
}

/* To avoid include hell, we can't include uaccess.h */
extern long copy_from_kernel_nofault(void *dst, const void *src, size_t size);

/**
 * 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.
 */
static inline unsigned long regs_get_kernel_stack_nth(struct pt_regs *regs,
						      unsigned int n)
{
	unsigned long *addr;
	unsigned long val;
	long ret;

	addr = regs_get_kernel_stack_nth_addr(regs, n);
	if (addr) {
		ret = copy_from_kernel_nofault(&val, addr, sizeof(val));
		if (!ret)
			return val;
	}
	return 0;
}

/**
 * regs_get_kernel_argument() - get Nth function argument in kernel
 * @regs:	pt_regs of that context
 * @n:		function argument number (start from 0)
 *
 * regs_get_argument() returns @n th argument of the function call.
 * Note that this chooses most probably assignment, in some case
 * it can be incorrect.
 * This is expected to be called from kprobes or ftrace with regs
 * where the top of stack is the return address.
 */
static inline unsigned long regs_get_kernel_argument(struct pt_regs *regs,
						     unsigned int n)
{
	static const unsigned int argument_offs[] = {
#ifdef __i386__
		offsetof(struct pt_regs, ax),
		offsetof(struct pt_regs, dx),
		offsetof(struct pt_regs, cx),
#define NR_REG_ARGUMENTS 3
#else
		offsetof(struct pt_regs, di),
		offsetof(struct pt_regs, si),
		offsetof(struct pt_regs, dx),
		offsetof(struct pt_regs, cx),
		offsetof(struct pt_regs, r8),
		offsetof(struct pt_regs, r9),
#define NR_REG_ARGUMENTS 6
#endif
	};

	if (n >= NR_REG_ARGUMENTS) {
		n -= NR_REG_ARGUMENTS - 1;
		return regs_get_kernel_stack_nth(regs, n);
	} else
		return regs_get_register(regs, argument_offs[n]);
}

#define arch_has_single_step()	(1)
#ifdef CONFIG_X86_DEBUGCTLMSR
#define arch_has_block_step()	(1)
#else
#define arch_has_block_step()	(boot_cpu_data.x86 >= 6)
#endif

#define ARCH_HAS_USER_SINGLE_STEP_REPORT

struct user_desc;
extern int do_get_thread_area(struct task_struct *p, int idx,
			      struct user_desc __user *info);
extern int do_set_thread_area(struct task_struct *p, int idx,
			      struct user_desc __user *info, int can_allocate);

#ifdef CONFIG_X86_64
# define do_set_thread_area_64(p, s, t)	do_arch_prctl_64(p, s, t)
#else
# define do_set_thread_area_64(p, s, t)	(0)
#endif

#endif /* !__ASSEMBLY__ */
#endif /* _ASM_X86_PTRACE_H */