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adf9ae0d15
In commit 9f0b4807a44f ("um: rework userspace stubs to not hard-code
stub location") I changed stub_segv_handler() to do a calculation with
a pointer to a stack variable to find the data page that we're using
for the stack and the rest of the data. This same commit was meant to
do it as well for stub_clone_handler(), but the change inadvertently
went into commit 84b2789d6115 ("um: separate child and parent errors
in clone stub") instead.
This was reported to not be compiled correctly by gcc 5, causing the
code to crash here. I'm not sure why, perhaps it's UB because the var
isn't initialized? In any case, this trick always seemed bad, so just
create a new inline function that does the calculation in assembly.
Reported-by: subashab@codeaurora.org
Fixes: 9f0b4807a44f ("um: rework userspace stubs to not hard-code stub location")
Fixes: 84b2789d6115 ("um: separate child and parent errors in clone stub")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
124 lines
2.4 KiB
C
124 lines
2.4 KiB
C
/*
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* Copyright (C) 2004 Jeff Dike (jdike@addtoit.com)
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* Licensed under the GPL
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*/
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#ifndef __SYSDEP_STUB_H
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#define __SYSDEP_STUB_H
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#include <sysdep/ptrace_user.h>
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#include <generated/asm-offsets.h>
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#define STUB_MMAP_NR __NR_mmap
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#define MMAP_OFFSET(o) (o)
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#define __syscall_clobber "r11","rcx","memory"
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#define __syscall "syscall"
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static inline long stub_syscall0(long syscall)
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{
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long ret;
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__asm__ volatile (__syscall
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: "=a" (ret)
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: "0" (syscall) : __syscall_clobber );
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return ret;
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}
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static inline long stub_syscall2(long syscall, long arg1, long arg2)
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{
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long ret;
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__asm__ volatile (__syscall
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: "=a" (ret)
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: "0" (syscall), "D" (arg1), "S" (arg2) : __syscall_clobber );
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return ret;
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}
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static inline long stub_syscall3(long syscall, long arg1, long arg2, long arg3)
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{
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long ret;
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__asm__ volatile (__syscall
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: "=a" (ret)
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: "0" (syscall), "D" (arg1), "S" (arg2), "d" (arg3)
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: __syscall_clobber );
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return ret;
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}
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static inline long stub_syscall4(long syscall, long arg1, long arg2, long arg3,
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long arg4)
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{
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long ret;
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__asm__ volatile ("movq %5,%%r10 ; " __syscall
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: "=a" (ret)
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: "0" (syscall), "D" (arg1), "S" (arg2), "d" (arg3),
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"g" (arg4)
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: __syscall_clobber, "r10" );
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return ret;
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}
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static inline long stub_syscall5(long syscall, long arg1, long arg2, long arg3,
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long arg4, long arg5)
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{
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long ret;
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__asm__ volatile ("movq %5,%%r10 ; movq %6,%%r8 ; " __syscall
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: "=a" (ret)
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: "0" (syscall), "D" (arg1), "S" (arg2), "d" (arg3),
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"g" (arg4), "g" (arg5)
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: __syscall_clobber, "r10", "r8" );
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return ret;
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}
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static inline void trap_myself(void)
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{
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__asm("int3");
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}
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static inline void remap_stack_and_trap(void)
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{
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__asm__ volatile (
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"movq %0,%%rax ;"
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"movq %%rsp,%%rdi ;"
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"andq %1,%%rdi ;"
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"movq %2,%%r10 ;"
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"movq %%rdi,%%r8 ; addq %3,%%r8 ; movq (%%r8),%%r8 ;"
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"movq %%rdi,%%r9 ; addq %4,%%r9 ; movq (%%r9),%%r9 ;"
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__syscall ";"
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"movq %%rsp,%%rdi ; andq %1,%%rdi ;"
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"addq %5,%%rdi ; movq %%rax, (%%rdi) ;"
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"int3"
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: :
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"g" (STUB_MMAP_NR),
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"g" (~(UM_KERN_PAGE_SIZE - 1)),
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"g" (MAP_FIXED | MAP_SHARED),
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"g" (UML_STUB_FIELD_FD),
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"g" (UML_STUB_FIELD_OFFSET),
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"g" (UML_STUB_FIELD_CHILD_ERR),
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"S" (UM_KERN_PAGE_SIZE),
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"d" (PROT_READ | PROT_WRITE)
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:
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__syscall_clobber, "r10", "r8", "r9");
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}
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static __always_inline void *get_stub_page(void)
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{
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unsigned long ret;
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asm volatile (
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"movq %%rsp,%0 ;"
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"andq %1,%0"
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: "=a" (ret)
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: "g" (~(UM_KERN_PAGE_SIZE - 1)));
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return (void *)ret;
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}
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#endif
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