Messages in this thread Patch in this message | | | Date | Sun, 12 Oct 2003 21:47:48 +0200 (MEST) | From | Mikael Pettersson <> | Subject | Re: non-modular 2.6 ppc kernels miscompiled by gcc-3.3.1? |
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On Sun, 12 Oct 2003 15:19:22 +0200, Benjamin Herrenschmidt wrote: >On Sun, 2003-10-12 at 15:10, Mikael Pettersson wrote: >> When I compile a non-modular 2.6 kernel for ppc with gcc-3.3.1, >> it oopses in __copy_tofrom_user() [copy_mount_options()] in >> user-space's first mount /proc call. User-space limps along >> for a while, oopsing in every mount call, and then hangs. >> >> This occurs with 2.6.0-test5, test6, and the test7-based >> linuxppc-2.5 tree (rsync:ed today). >> >> Enabling CONFIG_MODULES=y but still keeping everything built-in >> prevents the oopses. > >Smells like some section alignement issues. Can you check >how the __ex_table section is aligned and where __start___ex_table >points to ? (using objdump)
You're right, it turned out to be an alignment issue. Here's what my System.map looks like with gcc-3.3.1 and CONFIG_MODULES=n:
c017ba4d ? __start___kcrctab c017ba4d ? __start___kcrctab_gpl c017ba4d ? __start___ksymtab c017ba4d ? __start___ksymtab_gpl c017ba4d ? __stop___kcrctab c017ba4d ? __stop___kcrctab_gpl c017ba4d ? __stop___ksymtab c017ba4d ? __stop___ksymtab_gpl c017ba4d A __start___ex_table c017cf08 A __start___bug_table c017cf08 A __stop___ex_table c01801c8 A __stop___bug_table
Notice __start___ex_table[]'s address: it's not 4-byte aligned. With gcc-3.2.3 it got an 8-byte aligned address in my 2.6 kernel.
vmlinux.lds.S doesn't explicitly align __start___ex_table, so I simply put ". = ALIGN(4);" before it and Voila! now it works.
/Mikael
--- linuxppc-2.5/arch/ppc/kernel/vmlinux.lds.S.~1~ 2003-09-28 12:19:36.000000000 +0200 +++ linuxppc-2.5/arch/ppc/kernel/vmlinux.lds.S 2003-10-12 21:16:24.121283928 +0200 @@ -47,6 +47,7 @@ .fixup : { *(.fixup) } + . = ALIGN(4); __start___ex_table = .; __ex_table : { *(__ex_table) } __stop___ex_table = .; - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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