en Copyright 2025 Java http://opengrok.net:8080/history/linux/arch/arm64/kernel/static_call.c#441c63ff42c4e666304cdd32d23b5fc6bc1ea3cc Merge tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linuxPull arm64 fix from Will Deacon: - Implement a basic static call trampoline to fix CFI failures with the generic implementation* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: arm64: Use static call trampolines when kCFI is enabled List of files: /linux/arch/arm64/kernel/static_call.c Fri, 03 Apr 2026 15:47:13 +0000 Linus Torvalds <torvalds@linux-foundation.org> http://opengrok.net:8080/history/linux/arch/arm64/kernel/static_call.c#54ac9ff8f1196afc49d644a1625e0af1c9fcf7f5 arm64: Use static call trampolines when kCFI is enabledImplement arm64 support for the 'unoptimized' static call variety, whichroutes all calls through a trampoline that performs a tail call to thechosen function, and wire it up for use when kCFI is enabled. This worksaround an issue with kCFI and generic static calls, where the prototypesof default handlers such as __static_call_nop() and __static_call_ret0()don't match the expected prototype of the call site, resulting in kCFIfalse positives [0].Since static call targets may be located in modules loaded out of directbranching range, this needs an ADRP/LDR pair to load the branch targetinto R16 and a branch-to-register (BR) instruction to perform anindirect call.Unlike on x86, there is no pressing need on arm64 to avoid indirectcalls at all cost, but hiding it from the compiler as is done here doeshave some benefits:- the literal is located in .rodata, which gives us the same robustness advantage that code patching does;- no D-cache pollution from fetching hash values from .text sections.From an execution speed PoV, this is unlikely to make any difference atall.Cc: Sami Tolvanen <samitolvanen@google.com>Cc: Sean Christopherson <seanjc@google.com>Cc: Kees Cook <kees@kernel.org>Cc: Peter Zijlstra <peterz@infradead.org>Cc: Will McVicker <willmcvicker@google.com>Reported-by: Carlos Llamas <cmllamas@google.com>Closes: https://lore.kernel.org/all/20260311225822.1565895-1-cmllamas@google.com/ [0]Signed-off-by: Ard Biesheuvel <ardb@kernel.org>Signed-off-by: Will Deacon <will@kernel.org>Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> List of files: /linux/arch/arm64/kernel/static_call.c Tue, 31 Mar 2026 11:04:23 +0000 Ard Biesheuvel <ardb@kernel.org>