linux-kernel - [RFC PATCH PoC 01/11] x86/linkage: Add SYM_PI_ALIAS() macro helper to emit symbol aliases

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20250423110948.1103030-14-ardb+git@google.com>
Date: Wed, 23 Apr 2025 13:09:50 +0200
From: Ard Biesheuvel <ardb+git@...gle.com>
To: linux-kernel@...r.kernel.org
Cc: x86@...nel.org, mingo@...nel.org, Ard Biesheuvel <ardb@...nel.org>
Subject: [RFC PATCH PoC 01/11] x86/linkage: Add SYM_PI_ALIAS() macro helper to
 emit symbol aliases

From: Ard Biesheuvel <ardb@...nel.org>

Startup code that may execute from the early 1:1 mapping of memory will
be confined into its own address space, and only be permitted to access
ordinary kernel symbols if this is known to be safe.

Introduce a macro helper PI_ALIAS() that emits a __pi_ prefixed alias
for a symbol, which allows startup code to access it.

Signed-off-by: Ard Biesheuvel <ardb@...nel.org>
---
 arch/x86/include/asm/linkage.h | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/x86/include/asm/linkage.h b/arch/x86/include/asm/linkage.h
index b51d8a4673f5..ad59ff384f72 100644
--- a/arch/x86/include/asm/linkage.h
+++ b/arch/x86/include/asm/linkage.h
@@ -141,5 +141,11 @@
 #define SYM_FUNC_START_WEAK_NOALIGN(name)		\
 	SYM_START(name, SYM_L_WEAK, SYM_A_NONE)
 
+#ifdef __ASSEMBLER__
+#define SYM_PI_ALIAS(sym)	SYM_ALIAS(__pi_ ## sym, sym, SYM_L_GLOBAL)
+#else
+#define SYM_PI_ALIAS(sym)	extern typeof(sym) __PASTE(__pi_, sym) __alias(sym)
+#endif
+
 #endif /* _ASM_X86_LINKAGE_H */
 
-- 
2.49.0.805.g082f7c87e0-goog