From: Nathan Chancellor <nathan@kernel.org>
To: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
x86@kernel.org, Kees Cook <keescook@chromium.org>
Cc: Arnd Bergmann <arnd@arndb.de>,
Nick Desaulniers <ndesaulniers@google.com>,
linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com,
Nathan Chancellor <nathan@kernel.org>,
kernel test robot <lkp@intel.com>
Subject: [PATCH] vmlinux.lds.h: Handle decrypted data section with !SMP
Date: Wed, 5 May 2021 17:14:11 -0700 [thread overview]
Message-ID: <20210506001410.1026691-1-nathan@kernel.org> (raw)
With x86_64_defconfig and the following configs, there is an orphan
section warning:
CONFIG_SMP=n
CONFIG_AMD_MEM_ENCRYPT=y
CONFIG_HYPERVISOR_GUEST=y
CONFIG_KVM=y
CONFIG_PARAVIRT=y
ld: warning: orphan section `.data..decrypted' from `arch/x86/kernel/cpu/vmware.o' being placed in section `.data..decrypted'
ld: warning: orphan section `.data..decrypted' from `arch/x86/kernel/kvm.o' being placed in section `.data..decrypted'
These sections are created with DEFINE_PER_CPU_DECRYPTED, which
ultimately turns into __PCPU_ATTRS, which in turn has a section
attribute with a value of PER_CPU_BASE_SECTION + the section name. When
CONFIG_SMP is not set, the base section is .data and that is not
currently handled in any linker script.
Add .data..decrypted to PERCPU_DECRYPTED_SECTION, which is included in
PERCPU_INPUT -> PERCPU_SECTION, which is include in the x86 linker
script when either CONFIG_X86_64 or CONFIG_SMP is unset, taking care of
the warning.
Fixes: ac26963a1175 ("percpu: Introduce DEFINE_PER_CPU_DECRYPTED")
Link: https://github.com/ClangBuiltLinux/linux/issues/1360
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
---
I took the simple fix route with this patch since I highly doubt someone
is actually running a CONFIG_AMD_MEM_ENCRYPT=y + CONFIG_SMP=n kernel. If
this section should actually be in .data, I can respin.
include/asm-generic/vmlinux.lds.h | 1 +
1 file changed, 1 insertion(+)
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index 40a9c101565e..17325416e2de 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -960,6 +960,7 @@
#ifdef CONFIG_AMD_MEM_ENCRYPT
#define PERCPU_DECRYPTED_SECTION \
. = ALIGN(PAGE_SIZE); \
+ *(.data..decrypted) \
*(.data..percpu..decrypted) \
. = ALIGN(PAGE_SIZE);
#else
base-commit: 8404c9fbc84b741f66cff7d4934a25dd2c344452
--
2.31.1.442.g7e39198978
next reply other threads:[~2021-05-06 0:28 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-06 0:14 Nathan Chancellor [this message]
2021-05-06 18:15 ` [PATCH] vmlinux.lds.h: Handle decrypted data section with !SMP Nick Desaulniers
2021-06-04 18:03 ` Kees Cook
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