Messages in this thread | | | From | Arvind Sankar <> | Date | Sat, 16 May 2020 19:12:50 -0400 | Subject | Re: [PATCH v2] x86/boot: Correct relocation destination on old linkers |
| |
On Fri, Mar 13, 2020 at 02:33:50PM -0400, Arvind Sankar wrote: > On Fri, Feb 07, 2020 at 04:49:26PM -0500, Arvind Sankar wrote: > > For the 32-bit kernel, as described in commit 6d92bc9d483a ("x86/build: > > Build compressed x86 kernels as PIE"), pre-2.26 binutils generates > > R_386_32 relocations in PIE mode. Since the startup code does not > > perform relocation, any reloc entry with R_386_32 will remain as 0 in > > the executing code. > > > > Commit 974f221c84b0 ("x86/boot: Move compressed kernel to the end of the > > decompression buffer") added a new symbol _end but did not mark it > > hidden, which doesn't give the correct offset on older linkers. This > > causes the compressed kernel to be copied beyond the end of the > > decompression buffer, rather than flush against it. This region of > > memory may be reserved or already allocated for other purposes by the > > bootloader. > > > > Mark _end as hidden to fix. This changes the relocation from R_386_32 to > > R_386_RELATIVE even on the pre-2.26 binutils. > > > > For 64-bit, this is not strictly necessary, as the 64-bit kernel is only > > built as PIE if the linker supports -z noreloc-overflow, which implies > > binutils-2.27+, but for consistency, mark _end as hidden here too. > > > > Gentle reminder. > > https://lore.kernel.org/lkml/20200207214926.3564079-1-nivedita@alum.mit.edu/
Ping.
| |