Got it , Thanks for your explanation . > On Oct 16, 2015, at 18:57, Mark Rutland <mark.rutl...@arm.com> wrote: > > Hi, > > On Fri, Oct 16, 2015 at 06:46:07PM +0800, yalin wang wrote: >> Change to use memmove(), in case the dest address overlap with the >> source address. > > This cannot happen, and memove would not be sufficient if it did. > > The destination is a region returned by EFI_BOOT_SERVICES.AllocatePages, > which can only allocate pages which were free to begin with. Therefore > the new region cannot overlap with the stub (whose pages are not free). > > Were the new region to overlap with the stub, the memmove could corrupt > the code/data in use by the stub, and things would explode shortly > thereafter. > > Thanks, > Mark. > >> >> Signed-off-by: yalin wang <yalin.wang2...@gmail.com> >> --- >> arch/arm64/kernel/efi-stub.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/arch/arm64/kernel/efi-stub.c b/arch/arm64/kernel/efi-stub.c >> index 816120e..b6dc44b 100644 >> --- a/arch/arm64/kernel/efi-stub.c >> +++ b/arch/arm64/kernel/efi-stub.c >> @@ -59,7 +59,7 @@ efi_status_t __init handle_kernel_image(efi_system_table_t >> *sys_table_arg, >> } >> *image_addr = *reserve_addr + TEXT_OFFSET; >> } >> - memcpy((void *)*image_addr, old_image_addr, kernel_size); >> + memmove((void *)*image_addr, old_image_addr, kernel_size); >> *reserve_size = kernel_memsize; >> } >> >> -- >> 1.9.1 >>
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