From: Ard Biesheuvel <ard.biesheuvel@linaro.org> To: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, mpe@ellerman.id.au, jeyu@redhat.com Cc: will.deacon@arm.com, rusty@rustcorp.com.au, akpm@linux-foundation.org, benh@kernel.crashing.org, paulus@samba.org, Ard Biesheuvel <ard.biesheuvel@linaro.org> Subject: [PATCH v3 1/3] powerpc/reloc32: fix corrupted modversion CRCs Date: Thu, 27 Oct 2016 17:27:09 +0100 [thread overview] Message-ID: <1477585631-18574-2-git-send-email-ard.biesheuvel@linaro.org> (raw) In-Reply-To: <1477585631-18574-1-git-send-email-ard.biesheuvel@linaro.org> 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. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> --- 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
WARNING: multiple messages have this Message-ID (diff)
From: ard.biesheuvel@linaro.org (Ard Biesheuvel) To: linux-arm-kernel@lists.infradead.org Subject: [PATCH v3 1/3] powerpc/reloc32: fix corrupted modversion CRCs Date: Thu, 27 Oct 2016 17:27:09 +0100 [thread overview] Message-ID: <1477585631-18574-2-git-send-email-ard.biesheuvel@linaro.org> (raw) In-Reply-To: <1477585631-18574-1-git-send-email-ard.biesheuvel@linaro.org> 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. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> --- 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
next prev parent reply other threads:[~2016-10-27 16:27 UTC|newest] Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top 2016-10-27 16:27 [PATCH v3 0/3] modversions: Fix CRC mangling under CONFIG_RELOCATABLE=y Ard Biesheuvel 2016-10-27 16:27 ` Ard Biesheuvel 2016-10-27 16:27 ` Ard Biesheuvel [this message] 2016-10-27 16:27 ` [PATCH v3 1/3] powerpc/reloc32: fix corrupted modversion CRCs Ard Biesheuvel 2016-10-28 10:27 ` Suzuki K Poulose 2016-10-28 10:27 ` Suzuki K Poulose 2016-10-27 16:27 ` [PATCH v3 2/3] powerpc/reloc64: add support for 32-bit CRC pseudo-symbols Ard Biesheuvel 2016-10-27 16:27 ` Ard Biesheuvel 2016-11-25 11:29 ` Michael Ellerman 2016-11-25 11:29 ` Michael Ellerman 2016-11-25 12:48 ` Ard Biesheuvel 2016-11-25 12:48 ` Ard Biesheuvel 2016-12-01 9:39 ` Michael Ellerman 2016-12-01 9:39 ` Michael Ellerman 2016-12-01 9:45 ` Ard Biesheuvel 2016-12-01 9:45 ` Ard Biesheuvel 2016-12-01 16:28 ` Ard Biesheuvel 2016-12-01 16:28 ` Ard Biesheuvel 2016-10-27 16:27 ` [PATCH v3 3/3] modversions: treat symbol CRCs as 32 bit quantities on 64 bit archs Ard Biesheuvel 2016-10-27 16:27 ` Ard Biesheuvel 2016-11-04 9:55 ` [PATCH v3 0/3] modversions: Fix CRC mangling under CONFIG_RELOCATABLE=y Ard Biesheuvel 2016-11-04 9:55 ` Ard Biesheuvel 2016-11-10 4:22 ` Michael Ellerman 2016-11-10 4:22 ` Michael Ellerman 2016-11-15 9:13 ` Ard Biesheuvel 2016-11-15 9:13 ` Ard Biesheuvel 2016-11-25 8:44 ` Ard Biesheuvel 2016-11-25 8:44 ` Ard Biesheuvel 2016-11-25 11:12 ` Michael Ellerman 2016-11-25 11:12 ` Michael Ellerman 2016-11-16 19:23 ` Uwe Kleine-König 2016-11-16 19:23 ` Uwe Kleine-König 2016-11-16 20:29 ` Ard Biesheuvel 2016-11-16 20:29 ` Ard Biesheuvel
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