Messages in this thread | | | Date | Thu, 12 Dec 2013 07:42:24 -0800 | Subject | Re: RFC: binutils PATCH: Set e_type to ET_EXEC for -pie -Ttext-segment= | From | "H.J. Lu" <> |
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On Tue, Dec 10, 2013 at 2:47 PM, H.J. Lu <hjl.tools@gmail.com> wrote: > On Tue, Dec 10, 2013 at 2:36 PM, Alan Modra <amodra@gmail.com> wrote: >> On Mon, Dec 09, 2013 at 07:10:23PM -0800, H.J. Lu wrote: >>> Linker sets e_type in ELF header to ET_DYN for -pie -Ttext-segment=0xXXX. >>> When I added -Ttext-segment=0xXXX, one goal was to load >>> small model executable above 4GB on Linux/x86-64, which >>> was done with -pie -Ttext-segment=0xXXX. But -pie sets >>> e_type in ELF header to ET_DYN and kernel may ignore >>> p_vaddr in ELF header to load ET_DYN binary at a random >>> address. This patch changes ld to set e_type in ELF header >>> to ET_EXEC if the first PT_LOAD segment has non-zero >>> p_vaddr. If this is unacceptable as generic ELF change, >>> I can make it specific to x86. >> >> Well, I suppose it's a hack to use ET_DYN for executables in the first >> place, so one more hack in the linker hardly matters. Why not just >> patch the kernel though? The kernel can look at the first PT_LOAD >> header just as easily as the linker, and it's the kernel that is doing >> the loading after all. >> > > Kernel should have some freedom on where to load ET_DYN object. > But when -Ttext-segment= is used, programmer expects the > executable will be loaded at the specified address. Setting > ET_EXEC will guarantee that it will be loaded at that address. >
I checked it in with 2 testcases.
-- H.J.
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