From: "H.J. Lu" hjl.tools@gmail.com
commit 84d5f77fc2ee4e010c2c037750e32f06e55224b0 upstream.
In the x86 kernel, .exit.text and .exit.data sections are discarded at runtime, not by the linker. Add RUNTIME_DISCARD_EXIT to generic DISCARDS and define it in the x86 kernel linker script to keep them.
The sections are added before the DISCARD directive so document here only the situation explicitly as this change doesn't have any effect on the generated kernel. Also, other architectures like ARM64 will use it too so generalize the approach with the RUNTIME_DISCARD_EXIT define.
[ bp: Massage and extend commit message. ]
Signed-off-by: H.J. Lu hjl.tools@gmail.com Signed-off-by: Borislav Petkov bp@suse.de Reviewed-by: Kees Cook keescook@chromium.org Link: https://lkml.kernel.org/r/20200326193021.255002-1-hjl.tools@gmail.com Signed-off-by: Tom Saeger tom.saeger@oracle.com --- arch/x86/kernel/vmlinux.lds.S | 2 ++ include/asm-generic/vmlinux.lds.h | 11 +++++++++-- 2 files changed, 11 insertions(+), 2 deletions(-)
--- a/arch/x86/kernel/vmlinux.lds.S +++ b/arch/x86/kernel/vmlinux.lds.S @@ -21,6 +21,8 @@ #define LOAD_OFFSET __START_KERNEL_map #endif
+#define RUNTIME_DISCARD_EXIT + #include <asm-generic/vmlinux.lds.h> #include <asm/asm-offsets.h> #include <asm/thread_info.h> --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -900,10 +900,17 @@ * section definitions so that such archs put those in earlier section * definitions. */ +#ifdef RUNTIME_DISCARD_EXIT +#define EXIT_DISCARDS +#else +#define EXIT_DISCARDS \ + EXIT_TEXT \ + EXIT_DATA +#endif + #define DISCARDS \ /DISCARD/ : { \ - EXIT_TEXT \ - EXIT_DATA \ + EXIT_DISCARDS \ EXIT_CALL \ *(.discard) \ *(.discard.*) \