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| Kernel VM Library Functions | kvm_read(3KVM) |
| | kvm_read, kvm_write, kvm_uread, kvm_uwrite, kvm_kread, kvm_kwrite - copy data
to or from a kernel image or running system |
SYNOPSIS
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#include <kvm.h>
ssize_t kvm_read(kvm_t *kd, uintptr_t addr, void *buf, size_t nbytes); |
| | ssize_t kvm_write(kvm_t *kd, uintptr_t addr, void *buf, size_t nbytes); |
| | ssize_t kvm_kread(kvm_t *kd, uintptr_t addr, void *buf, size_t nbytes); |
| | ssize_t kvm_kwrite(kvm_t *kd, uintptr_t addr, void *buf, size_t nbytes); |
| | ssize_t kvm_uread(kvm_t *kd, uintptr_t addr, void *buf, size_t nbytes); |
| | ssize_t kvm_uwrite(kvm_t *kd, uintptr_t addr, void *buf, size_t nbytes); |
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kvm_kread
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The kvm_kread() function transfers data from the kernel address space to the address space of the process. nbytes bytes of data are copied from the kernel
virtual address given by addr to the buffer pointed to by buf.
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kvm_kwrite
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The kvm_kwrite() function is like kvm_kread(), except that the direction of the transfer is reversed. To use this function, the kvm_open(3KVM) call that returned kd must have specified write access.
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kvm_uread
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The kvm_uread() function transfers data from the address space of the processes specified in the most recent kvm_getu(3KVM) call. nbytes bytes of data are copied from the user virtual address given by addr to the buffer pointed to by buf.
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kvm_uwrite
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The kvm_uwrite() function is like kvm_uread(), except that the direction of the transfer is reversed. To use this function, the kvm_open(3KVM) call that returned kd must have specified write access. The address is resolved in the
address space of the process specified in the most recent kvm_getu(3KVM) call.
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kvm_read
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The kvm_read() function transfers data from the kernel image specified by kd (see kvm_open(3KVM)) to the address space of the process. nbytes bytes of data are copied from the kernel virtual address given by addr to the buffer pointed to by buf.
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kvm_write
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The kvm_write() function is like kvm_read(), except that the direction of data transfer is reversed. To use this function, the kvm_open(3KVM) call that returned kd must have specified write access. If a user virtual address is given,
it is resolved in the address space of the process specified in the most recent kvm_getu(3KVM)
call.
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The use of kvm_read() and kvm_write() is strongly discouraged. On some platforms, there is considerable ambiguity over which address space is to be accessed by
these functions, possibly leading to unexpected results. The kvm_kread(), kvm_kwrite(), kvm_uread(), and kvm_uwrite() functions
are much more clearly defined in this respect.
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On success, these functions return the number of bytes actually transferred. On failure, they return -1.
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See attributes(5) for descriptions of the following
attributes:
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
| MT-Level | Unsafe |
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