From 4b9880dbf3bdba3a7c56445137c3d0e30aaa0a40 Mon Sep 17 00:00:00 2001 From: Michael Ellerman Date: Thu, 5 Jan 2023 22:05:04 +1100 Subject: [PATCH 1/3] powerpc/vmlinux.lds: Define RUNTIME_DISCARD_EXIT The powerpc linker script explicitly includes .exit.text, because otherwise the link fails due to references from __bug_table and __ex_table. The code is freed (discarded) at runtime along with .init.text and data. That has worked in the past despite powerpc not defining RUNTIME_DISCARD_EXIT because DISCARDS appears late in the powerpc linker script (line 410), and the explicit inclusion of .exit.text earlier (line 280) supersedes the discard. However commit 99cb0d917ffa ("arch: fix broken BuildID for arm64 and riscv") introduced an earlier use of DISCARD as part of the RO_DATA macro (line 136). With binutils < 2.36 that causes the DISCARD directives later in the script to be applied earlier [1], causing .exit.text to actually be discarded at link time, leading to build errors: '.exit.text' referenced in section '__bug_table' of crypto/algboss.o: defined in discarded section '.exit.text' of crypto/algboss.o '.exit.text' referenced in section '__ex_table' of drivers/nvdimm/core.o: defined in discarded section '.exit.text' of drivers/nvdimm/core.o Fix it by defining RUNTIME_DISCARD_EXIT, which causes the generic DISCARDS macro to not include .exit.text at all. 1: https://lore.kernel.org/lkml/87fscp2v7k.fsf@igel.home/ Fixes: 99cb0d917ffa ("arch: fix broken BuildID for arm64 and riscv") Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20230105132349.384666-1-mpe@ellerman.id.au --- arch/powerpc/kernel/vmlinux.lds.S | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/powerpc/kernel/vmlinux.lds.S b/arch/powerpc/kernel/vmlinux.lds.S index 8c3862b4c259..c5ea7d03d539 100644 --- a/arch/powerpc/kernel/vmlinux.lds.S +++ b/arch/powerpc/kernel/vmlinux.lds.S @@ -8,6 +8,7 @@ #define BSS_FIRST_SECTIONS *(.bss.prominit) #define EMITS_PT_NOTE #define RO_EXCEPTION_TABLE_ALIGN 0 +#define RUNTIME_DISCARD_EXIT #define SOFT_MASK_TABLE(align) \ . = ALIGN(align); \ From 07b050f9290ee012a407a0f64151db902a1520f5 Mon Sep 17 00:00:00 2001 From: Michael Ellerman Date: Thu, 5 Jan 2023 22:28:36 +1100 Subject: [PATCH 2/3] powerpc/vmlinux.lds: Don't discard .rela* for relocatable builds Relocatable kernels must not discard relocations, they need to be processed at runtime. As such they are included for CONFIG_RELOCATABLE builds in the powerpc linker script (line 340). However they are also unconditionally discarded later in the script (line 414). Previously that worked because the earlier inclusion superseded the discard. However commit 99cb0d917ffa ("arch: fix broken BuildID for arm64 and riscv") introduced an earlier use of DISCARD as part of the RO_DATA macro (line 137). With binutils < 2.36 that causes the DISCARD directives later in the script to be applied earlier, causing .rela* to actually be discarded at link time, leading to build warnings and a kernel that doesn't boot: ld: warning: discarding dynamic section .rela.init.rodata Fix it by conditionally discarding .rela* only when CONFIG_RELOCATABLE is disabled. Fixes: 99cb0d917ffa ("arch: fix broken BuildID for arm64 and riscv") Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20230105132349.384666-2-mpe@ellerman.id.au --- arch/powerpc/kernel/vmlinux.lds.S | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/kernel/vmlinux.lds.S b/arch/powerpc/kernel/vmlinux.lds.S index c5ea7d03d539..a4c6efadc90c 100644 --- a/arch/powerpc/kernel/vmlinux.lds.S +++ b/arch/powerpc/kernel/vmlinux.lds.S @@ -411,9 +411,12 @@ SECTIONS DISCARDS /DISCARD/ : { *(*.EMB.apuinfo) - *(.glink .iplt .plt .rela* .comment) + *(.glink .iplt .plt .comment) *(.gnu.version*) *(.gnu.attributes) *(.eh_frame) +#ifndef CONFIG_RELOCATABLE + *(.rela*) +#endif } } From be5f95c8779e19779dd81927c8574fec5aaba36c Mon Sep 17 00:00:00 2001 From: Michael Ellerman Date: Thu, 5 Jan 2023 22:42:59 +1100 Subject: [PATCH 3/3] powerpc/vmlinux.lds: Don't discard .comment Although the powerpc linker script mentions .comment in the DISCARD section, that has never actually caused it to be discarded, because the earlier ELF_DETAILS macro (previously STABS_DEBUG) explicitly includes .comment. However commit 99cb0d917ffa ("arch: fix broken BuildID for arm64 and riscv") introduced an earlier use of DISCARD as part of the RO_DATA macro. With binutils < 2.36 that causes the DISCARD directives later in the script to be applied earlier, causing .comment to actually be discarded. It's confusing to explicitly include and discard .comment, and even more so if the behaviour depends on the toolchain version. So don't discard .comment in order to maintain the existing behaviour in all cases. Fixes: 83a092cf95f2 ("powerpc: Link warning for orphan sections") Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20230105132349.384666-3-mpe@ellerman.id.au --- arch/powerpc/kernel/vmlinux.lds.S | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/powerpc/kernel/vmlinux.lds.S b/arch/powerpc/kernel/vmlinux.lds.S index a4c6efadc90c..958e77a24f85 100644 --- a/arch/powerpc/kernel/vmlinux.lds.S +++ b/arch/powerpc/kernel/vmlinux.lds.S @@ -411,7 +411,7 @@ SECTIONS DISCARDS /DISCARD/ : { *(*.EMB.apuinfo) - *(.glink .iplt .plt .comment) + *(.glink .iplt .plt) *(.gnu.version*) *(.gnu.attributes) *(.eh_frame)