From 73f44fe19d359635a607e8e8daa0da4001c1cfc2 Mon Sep 17 00:00:00 2001 From: Josh Poimboeuf Date: Wed, 27 Jan 2021 17:18:37 -0600 Subject: static_call: Allow module use without exposing static_call_key When exporting static_call_key; with EXPORT_STATIC_CALL*(), the module can use static_call_update() to change the function called. This is not desirable in general. Not exporting static_call_key however also disallows usage of static_call(), since objtool needs the key to construct the static_call_site. Solve this by allowing objtool to create the static_call_site using the trampoline address when it builds a module and cannot find the static_call_key symbol. The module loader will then try and map the trampole back to a key before it constructs the normal sites list. Doing this requires a trampoline -> key associsation, so add another magic section that keeps those. Originally-by: Peter Zijlstra (Intel) Signed-off-by: Josh Poimboeuf Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Link: https://lkml.kernel.org/r/20210127231837.ifddpn7rhwdaepiu@treble --- include/asm-generic/vmlinux.lds.h | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'include/asm-generic') diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h index b97c628ad91f..3f747de1934d 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -393,7 +393,10 @@ . = ALIGN(8); \ __start_static_call_sites = .; \ KEEP(*(.static_call_sites)) \ - __stop_static_call_sites = .; + __stop_static_call_sites = .; \ + __start_static_call_tramp_key = .; \ + KEEP(*(.static_call_tramp_key)) \ + __stop_static_call_tramp_key = .; /* * Allow architectures to handle ro_after_init data on their -- cgit v1.2.3