From: Arvind Sankar <firstname.lastname@example.org> To: Arvind Sankar <email@example.com> Cc: Thomas Gleixner <firstname.lastname@example.org>, Ingo Molnar <email@example.com>, Borislav Petkov <firstname.lastname@example.org>, "H. Peter Anvin" <email@example.com>, firstname.lastname@example.org, email@example.com, "H.J. Lu" <firstname.lastname@example.org> Subject: Re: [PATCH v2] x86/boot: Correct relocation destination on old linkers Date: Fri, 13 Mar 2020 14:33:50 -0400 [thread overview] Message-ID: <20200313183349.GA1544820@rani.riverdale.lan> (raw) In-Reply-To: <email@example.com> 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://firstname.lastname@example.org/
next prev parent reply other threads:[~2020-03-13 18:33 UTC|newest] Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-01-11 19:00 [PATCH] x86/boot/compressed: " Arvind Sankar 2020-02-07 21:49 ` [PATCH v2] x86/boot: " Arvind Sankar 2020-03-13 18:33 ` Arvind Sankar [this message] 2020-05-16 23:12 ` Arvind Sankar 2020-05-19 12:35 ` [tip: x86/boot] " tip-bot2 for Arvind Sankar
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