From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-x235.google.com (mail-wm0-x235.google.com [IPv6:2a00:1450:400c:c09::235]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3v30TJ08M2zDqKV for ; Wed, 18 Jan 2017 06:26:28 +1100 (AEDT) Received: by mail-wm0-x235.google.com with SMTP id d140so23297999wmd.0 for ; Tue, 17 Jan 2017 11:26:27 -0800 (PST) From: Ard Biesheuvel To: linux-kernel@vger.kernel.org, mpe@ellerman.id.au, jeyu@redhat.com Cc: rusty@rustcorp.com.au, suzuki.poulose@arm.com, will.deacon@arm.com, akpm@linux-foundation.org, benh@kernel.crashing.org, paulus@samba.org, arnd@arndb.de, torvalds@linux-foundation.org, viro@zeniv.linux.org.uk, linuxppc-dev@lists.ozlabs.org, Ard Biesheuvel Subject: [PATCH v4 1/3] powerpc/reloc32: fix corrupted modversion CRCs Date: Tue, 17 Jan 2017 19:26:11 +0000 Message-Id: <1484681173-11644-2-git-send-email-ard.biesheuvel@linaro.org> In-Reply-To: <1484681173-11644-1-git-send-email-ard.biesheuvel@linaro.org> References: <1484681173-11644-1-git-send-email-ard.biesheuvel@linaro.org> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Commit 0e0ed6406e61 ("powerpc/modules: Module CRC relocation fix causes perf issues") fixed an issue with relocatable PIE kernels in a way that essentially reintroduced the issue again for 32-bit builds. Since the chosen approach does is not applicable to 32-bit, fix the issue by updating the runtime relocation routine to ignore the load offset for the interval [__start___kcrctab, __stop___kcrctab_gpl_future), which is where the CRCs reside. This ensures that the values of the CRC pseudo-symbols are no longer made dependent on the runtime load offset. Reviewed-by: Suzuki K Poulose Signed-off-by: Ard Biesheuvel --- arch/powerpc/kernel/reloc_32.S | 36 +++++++++++++++++--- 1 file changed, 32 insertions(+), 4 deletions(-) diff --git a/arch/powerpc/kernel/reloc_32.S b/arch/powerpc/kernel/reloc_32.S index f366fedb0872..150686b9febb 100644 --- a/arch/powerpc/kernel/reloc_32.S +++ b/arch/powerpc/kernel/reloc_32.S @@ -87,12 +87,12 @@ eodyn: /* End of Dyn Table scan */ * Work out the current offset from the link time address of .rela * section. * cur_offset[r7] = rela.run[r9] - rela.link [r7] - * _stext.link[r12] = _stext.run[r10] - cur_offset[r7] - * final_offset[r3] = _stext.final[r3] - _stext.link[r12] + * _stext.link[r11] = _stext.run[r10] - cur_offset[r7] + * final_offset[r3] = _stext.final[r3] - _stext.link[r11] */ subf r7, r7, r9 /* cur_offset */ - subf r12, r7, r10 - subf r3, r12, r3 /* final_offset */ + subf r11, r7, r10 + subf r3, r11, r3 /* final_offset */ subf r8, r6, r8 /* relaz -= relaent */ /* @@ -101,6 +101,21 @@ eodyn: /* End of Dyn Table scan */ * r13 - points to the symbol table */ +#ifdef CONFIG_MODVERSIONS + /* + * Treat R_PPC_RELATIVE relocations differently when they target the + * interval [__start___kcrctab, __stop___kcrctab_gpl_future): in this + * case, the relocated quantities are CRC pseudo-symbols, which should + * be preserved as-is, rather than be modified to take the runtime + * offset into account. + */ + lwz r10, (p_kcrc_start - 0b)(r12) + lwz r11, (p_kcrc_stop - 0b)(r12) + subf r12, r7, r12 /* link time addr of 0b */ + add r10, r10, r12 + add r11, r11, r12 +#endif + /* * Check if we have a relocation based on symbol * r5 will hold the value of the symbol. @@ -135,7 +150,15 @@ get_type: bne hi16 lwz r4, 0(r9) /* r_offset */ lwz r0, 8(r9) /* r_addend */ +#ifdef CONFIG_MODVERSIONS + cmplw r4, r10 + blt do_add + cmplw r4, r11 + blt skip_add +do_add: +#endif add r0, r0, r3 /* final addend */ +skip_add: stwx r0, r4, r7 /* memory[r4+r7]) = (u32)r0 */ b nxtrela /* continue */ @@ -207,3 +230,8 @@ p_dyn: .long __dynamic_start - 0b p_rela: .long __rela_dyn_start - 0b p_sym: .long __dynamic_symtab - 0b p_st: .long _stext - 0b + +#ifdef CONFIG_MODVERSIONS +p_kcrc_start: .long __start___kcrctab - 0b +p_kcrc_stop: .long __stop___kcrctab_gpl_future - 0b +#endif -- 2.7.4