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9802d86585
Error injection is sloppy and very ad-hoc. BPF could fill this niche perfectly with it's kprobe functionality. We could make sure errors are only triggered in specific call chains that we care about with very specific situations. Accomplish this with the bpf_override_funciton helper. This will modify the probe'd callers return value to the specified value and set the PC to an override function that simply returns, bypassing the originally probed function. This gives us a nice clean way to implement systematic error injection for all of our code paths. Acked-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
291 lines
7.8 KiB
C
291 lines
7.8 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _ASM_X86_PTRACE_H
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#define _ASM_X86_PTRACE_H
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#include <asm/segment.h>
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#include <asm/page_types.h>
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#include <uapi/asm/ptrace.h>
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#ifndef __ASSEMBLY__
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#ifdef __i386__
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struct pt_regs {
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/*
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* NB: 32-bit x86 CPUs are inconsistent as what happens in the
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* following cases (where %seg represents a segment register):
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*
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* - pushl %seg: some do a 16-bit write and leave the high
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* bits alone
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* - movl %seg, [mem]: some do a 16-bit write despite the movl
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* - IDT entry: some (e.g. 486) will leave the high bits of CS
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* and (if applicable) SS undefined.
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*
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* Fortunately, x86-32 doesn't read the high bits on POP or IRET,
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* so we can just treat all of the segment registers as 16-bit
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* values.
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*/
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unsigned long bx;
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unsigned long cx;
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unsigned long dx;
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unsigned long si;
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unsigned long di;
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unsigned long bp;
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unsigned long ax;
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unsigned short ds;
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unsigned short __dsh;
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unsigned short es;
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unsigned short __esh;
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unsigned short fs;
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unsigned short __fsh;
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unsigned short gs;
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unsigned short __gsh;
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unsigned long orig_ax;
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unsigned long ip;
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unsigned short cs;
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unsigned short __csh;
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unsigned long flags;
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unsigned long sp;
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unsigned short ss;
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unsigned short __ssh;
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};
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#else /* __i386__ */
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struct pt_regs {
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/*
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* C ABI says these regs are callee-preserved. They aren't saved on kernel entry
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* unless syscall needs a complete, fully filled "struct pt_regs".
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*/
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unsigned long r15;
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unsigned long r14;
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unsigned long r13;
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unsigned long r12;
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unsigned long bp;
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unsigned long bx;
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/* These regs are callee-clobbered. Always saved on kernel entry. */
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unsigned long r11;
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unsigned long r10;
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unsigned long r9;
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unsigned long r8;
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unsigned long ax;
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unsigned long cx;
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unsigned long dx;
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unsigned long si;
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unsigned long di;
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/*
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* On syscall entry, this is syscall#. On CPU exception, this is error code.
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* On hw interrupt, it's IRQ number:
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*/
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unsigned long orig_ax;
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/* Return frame for iretq */
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unsigned long ip;
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unsigned long cs;
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unsigned long flags;
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unsigned long sp;
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unsigned long ss;
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/* top of stack page */
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};
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#endif /* !__i386__ */
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#ifdef CONFIG_PARAVIRT
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#include <asm/paravirt_types.h>
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#endif
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struct cpuinfo_x86;
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struct task_struct;
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extern unsigned long profile_pc(struct pt_regs *regs);
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#define profile_pc profile_pc
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extern unsigned long
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convert_ip_to_linear(struct task_struct *child, struct pt_regs *regs);
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extern void send_sigtrap(struct task_struct *tsk, struct pt_regs *regs,
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int error_code, int si_code);
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static inline unsigned long regs_return_value(struct pt_regs *regs)
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{
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return regs->ax;
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}
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static inline void regs_set_return_value(struct pt_regs *regs, unsigned long rc)
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{
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regs->ax = rc;
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}
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/*
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* user_mode(regs) determines whether a register set came from user
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* mode. On x86_32, this is true if V8086 mode was enabled OR if the
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* register set was from protected mode with RPL-3 CS value. This
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* tricky test checks that with one comparison.
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*
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* On x86_64, vm86 mode is mercifully nonexistent, and we don't need
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* the extra check.
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*/
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static inline int user_mode(struct pt_regs *regs)
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{
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#ifdef CONFIG_X86_32
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return ((regs->cs & SEGMENT_RPL_MASK) | (regs->flags & X86_VM_MASK)) >= USER_RPL;
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#else
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return !!(regs->cs & 3);
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#endif
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}
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static inline int v8086_mode(struct pt_regs *regs)
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{
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#ifdef CONFIG_X86_32
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return (regs->flags & X86_VM_MASK);
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#else
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return 0; /* No V86 mode support in long mode */
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#endif
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}
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static inline bool user_64bit_mode(struct pt_regs *regs)
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{
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#ifdef CONFIG_X86_64
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#ifndef CONFIG_PARAVIRT
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/*
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* On non-paravirt systems, this is the only long mode CPL 3
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* selector. We do not allow long mode selectors in the LDT.
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*/
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return regs->cs == __USER_CS;
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#else
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/* Headers are too twisted for this to go in paravirt.h. */
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return regs->cs == __USER_CS || regs->cs == pv_info.extra_user_64bit_cs;
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#endif
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#else /* !CONFIG_X86_64 */
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return false;
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#endif
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}
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#ifdef CONFIG_X86_64
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#define current_user_stack_pointer() current_pt_regs()->sp
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#define compat_user_stack_pointer() current_pt_regs()->sp
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#endif
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#ifdef CONFIG_X86_32
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extern unsigned long kernel_stack_pointer(struct pt_regs *regs);
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#else
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static inline unsigned long kernel_stack_pointer(struct pt_regs *regs)
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{
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return regs->sp;
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}
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#endif
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#define GET_IP(regs) ((regs)->ip)
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#define GET_FP(regs) ((regs)->bp)
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#define GET_USP(regs) ((regs)->sp)
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#include <asm-generic/ptrace.h>
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/* Query offset/name of register from its name/offset */
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extern int regs_query_register_offset(const char *name);
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extern const char *regs_query_register_name(unsigned int offset);
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#define MAX_REG_OFFSET (offsetof(struct pt_regs, ss))
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/**
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* regs_get_register() - get register value from its offset
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* @regs: pt_regs from which register value is gotten.
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* @offset: offset number of the register.
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*
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* regs_get_register returns the value of a register. The @offset is the
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* offset of the register in struct pt_regs address which specified by @regs.
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* If @offset is bigger than MAX_REG_OFFSET, this returns 0.
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*/
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static inline unsigned long regs_get_register(struct pt_regs *regs,
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unsigned int offset)
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{
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if (unlikely(offset > MAX_REG_OFFSET))
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return 0;
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#ifdef CONFIG_X86_32
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/*
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* Traps from the kernel do not save sp and ss.
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* Use the helper function to retrieve sp.
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*/
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if (offset == offsetof(struct pt_regs, sp) &&
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regs->cs == __KERNEL_CS)
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return kernel_stack_pointer(regs);
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/* The selector fields are 16-bit. */
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if (offset == offsetof(struct pt_regs, cs) ||
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offset == offsetof(struct pt_regs, ss) ||
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offset == offsetof(struct pt_regs, ds) ||
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offset == offsetof(struct pt_regs, es) ||
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offset == offsetof(struct pt_regs, fs) ||
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offset == offsetof(struct pt_regs, gs)) {
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return *(u16 *)((unsigned long)regs + offset);
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}
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#endif
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return *(unsigned long *)((unsigned long)regs + offset);
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}
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/**
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* regs_within_kernel_stack() - check the address in the stack
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* @regs: pt_regs which contains kernel stack pointer.
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* @addr: address which is checked.
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*
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* regs_within_kernel_stack() checks @addr is within the kernel stack page(s).
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* If @addr is within the kernel stack, it returns true. If not, returns false.
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*/
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static inline int regs_within_kernel_stack(struct pt_regs *regs,
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unsigned long addr)
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{
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return ((addr & ~(THREAD_SIZE - 1)) ==
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(kernel_stack_pointer(regs) & ~(THREAD_SIZE - 1)));
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}
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/**
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* regs_get_kernel_stack_nth() - get Nth entry of the stack
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* @regs: pt_regs which contains kernel stack pointer.
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* @n: stack entry number.
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*
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* regs_get_kernel_stack_nth() returns @n th entry of the kernel stack which
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* is specified by @regs. If the @n th entry is NOT in the kernel stack,
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* this returns 0.
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*/
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static inline unsigned long regs_get_kernel_stack_nth(struct pt_regs *regs,
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unsigned int n)
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{
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unsigned long *addr = (unsigned long *)kernel_stack_pointer(regs);
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addr += n;
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if (regs_within_kernel_stack(regs, (unsigned long)addr))
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return *addr;
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else
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return 0;
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}
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#define arch_has_single_step() (1)
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#ifdef CONFIG_X86_DEBUGCTLMSR
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#define arch_has_block_step() (1)
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#else
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#define arch_has_block_step() (boot_cpu_data.x86 >= 6)
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#endif
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#define ARCH_HAS_USER_SINGLE_STEP_INFO
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/*
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* When hitting ptrace_stop(), we cannot return using SYSRET because
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* that does not restore the full CPU state, only a minimal set. The
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* ptracer can change arbitrary register values, which is usually okay
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* because the usual ptrace stops run off the signal delivery path which
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* forces IRET; however, ptrace_event() stops happen in arbitrary places
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* in the kernel and don't force IRET path.
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*
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* So force IRET path after a ptrace stop.
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*/
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#define arch_ptrace_stop_needed(code, info) \
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({ \
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force_iret(); \
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false; \
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})
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struct user_desc;
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extern int do_get_thread_area(struct task_struct *p, int idx,
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struct user_desc __user *info);
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extern int do_set_thread_area(struct task_struct *p, int idx,
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struct user_desc __user *info, int can_allocate);
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#endif /* !__ASSEMBLY__ */
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#endif /* _ASM_X86_PTRACE_H */
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