]> git.ipfire.org Git - thirdparty/kernel/linux.git/commitdiff
x86/linkage: Add SYM_PIC_ALIAS() macro helper to emit symbol aliases
authorArd Biesheuvel <ardb@kernel.org>
Sun, 4 May 2025 09:52:43 +0000 (11:52 +0200)
committerIngo Molnar <mingo@kernel.org>
Sun, 4 May 2025 13:59:43 +0000 (15:59 +0200)
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 SYM_PIC_ALIAS() that emits a __pi_ prefixed
alias for a symbol, which allows startup code to access it.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: David Woodhouse <dwmw@amazon.co.uk>
Cc: Dionna Amalie Glaze <dionnaglaze@google.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Kevin Loughlin <kevinloughlin@google.com>
Cc: Len Brown <len.brown@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: linux-efi@vger.kernel.org
Link: https://lore.kernel.org/r/20250504095230.2932860-38-ardb+git@google.com
arch/x86/include/asm/linkage.h

index b51d8a4673f58fa8aee49fda3f28acfdbea48f48..9d38ae744a2e4af91c78048cd8fb26ab92ac2ba4 100644 (file)
 #define SYM_FUNC_START_WEAK_NOALIGN(name)              \
        SYM_START(name, SYM_L_WEAK, SYM_A_NONE)
 
+/*
+ * Expose 'sym' to the startup code in arch/x86/boot/startup/, by emitting an
+ * alias prefixed with __pi_
+ */
+#ifdef __ASSEMBLER__
+#define SYM_PIC_ALIAS(sym)     SYM_ALIAS(__pi_ ## sym, sym, SYM_L_GLOBAL)
+#else
+#define SYM_PIC_ALIAS(sym)     extern typeof(sym) __PASTE(__pi_, sym) __alias(sym)
+#endif
+
 #endif /* _ASM_X86_LINKAGE_H */