Re: [PATCH] module: set __jump_table alignment to 8
From: Michael Ellerman <mpe@ellerman.id.au>
Date: 2017-03-02 10:58:26
Also in:
linux-arm-kernel, linux-mips, lkml
David Daney [off-list ref] writes:
For powerpc the __jump_table section in modules is not aligned, this causes a WARN_ON() splat when loading a module containing a __jump_table.
Thanks for doing the patch. If it helps: Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Strict alignment became necessary with commit 3821fd35b58d
("jump_label: Reduce the size of struct static_key"), currently in
linux-next, which uses the two least significant bits of pointers to
__jump_table elements.It would obviously be nice if this could go in before the commit that exposes the breakage, but I guess that's problematic because Steve doesn't want to rebase the tracing tree. Steve I think you've already sent your pull request for this cycle? So I guess if this can go in your first batch of fixes? Or we could just send it directly to Linus? cheers
quoted hunk ↗ jump to hunk
Fix by forcing __jump_table to 8, which is the same alignment used for this section in the kernel proper. Signed-off-by: David Daney <redacted> Tested-by: Sachin Sant <redacted> --- scripts/module-common.lds | 2 ++ 1 file changed, 2 insertions(+)diff --git a/scripts/module-common.lds b/scripts/module-common.lds index 73a2c7d..53234e8 100644 --- a/scripts/module-common.lds +++ b/scripts/module-common.lds@@ -19,4 +19,6 @@ SECTIONS { . = ALIGN(8); .init_array 0 : { *(SORT(.init_array.*)) *(.init_array) } + + __jump_table 0 : ALIGN(8) { KEEP(*(__jump_table)) } }-- 2.9.3