diff mbox series

[05/46] compiler.h: introduce __global_on_lto

Message ID	20221114114344.18650-6-jirislaby@kernel.org
State	New
Headers	Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; From: "Jiri Slaby (SUSE)" <jirislaby@kernel.org> To: linux-kernel@vger.kernel.org Cc: Jiri Slaby <jslaby@suse.cz>, Martin Liska <mliska@suse.cz> Subject: [PATCH 05/46] compiler.h: introduce __global_on_lto Date: Mon, 14 Nov 2022 12:43:03 +0100 Message-Id: <20221114114344.18650-6-jirislaby@kernel.org> In-Reply-To: <20221114114344.18650-1-jirislaby@kernel.org> References: <20221114114344.18650-1-jirislaby@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk
Series	gcc-LTO support for the kernel \| [00/46] gcc-LTO support for the kernel [01/46] x86/boot: robustify calling startup_{32,64}() from the decompressor code [02/46] kbuild: pass jobserver to cmd_ld_vmlinux.o [03/46] kbuild: lto: preserve MAKEFLAGS for module linking [04/46] compiler.h: introduce __visible_on_lto [05/46] compiler.h: introduce __global_on_lto [06/46] Compiler Attributes, lto: introduce __noreorder [07/46] tracepoint, lto: Mark static call functions as __visible [08/46] static_call, lto: Mark static keys as __visible [09/46] static_call, lto: Mark static_call_return0() as __visible [10/46] static_call, lto: Mark func_a() as __visible_on_lto [11/46] x86/alternative, lto: Mark int3_() as global and __visible [12/46] x86/paravirt, lto: Mark native_steal_clock() as __visible_on_lto [13/46] x86/preempt, lto: Mark preempt_schedule_thunk() as __visible [14/46] x86/sev, lto: Mark cpuid_table_copy as __visible_on_lto [15/46] x86/xen, lto: Mark xen_vcpu_stolen() as __visible [16/46] x86, lto: Mark gdt_page and native_sched_clock() as __visible [17/46] amd, lto: Mark amd pmu and pstate functions as __visible_on_lto [18/46] entry, lto: Mark raw_irqentry_exit_cond_resched() as __visible [19/46] export, lto: Mark __kstrtab* in EXPORT_SYMBOL() as global and __visible [20/46] softirq, lto: Mark irq_enter/exit_rcu() as __visible [21/46] btf, lto: pass scope as strings [22/46] btf, lto: Make all BTF IDs global on LTO [23/46] init.h, lto: mark initcalls as __noreorder [24/46] bpf, lto: mark interpreter jump table as __noreorder [25/46] sched, lto: mark sched classes as __noreorder [26/46] x86/apic, lto: Mark apic_driver*() as __noreorder [27/46] linkage, lto: use C version for SYSCALL_ALIAS() / cond_syscall() [28/46] scripts, lto: re-add gcc-ld [29/46] scripts, lto: use CONFIG_LTO for many LTO specific actions [30/46] Kbuild, lto: Add Link Time Optimization support [31/46] x86/purgatory, lto: Disable gcc LTO for purgatory [32/46] x86/realmode, lto: Disable gcc LTO for real mode code [33/46] x86/vdso, lto: Disable gcc LTO for the vdso [34/46] scripts, lto: disable gcc LTO for some mod sources [35/46] Kbuild, lto: disable gcc LTO for bounds+asm-offsets [36/46] lib/string, lto: disable gcc LTO for string.o [37/46] Compiler attributes, lto: disable __flatten with LTO [38/46] Kbuild, lto: don't include weak source file symbols in System.map [39/46] x86, lto: Disable relative init pointers with gcc LTO [40/46] x86/livepatch, lto: Disable live patching with gcc LTO [41/46] x86/lib, lto: Mark 32bit mem{cpy,move,set} as __used [42/46] mm/kasan, lto: Mark kasan mem{cpy,move,set} as __used [43/46] scripts, lto: check C symbols for modversions [44/46] scripts/bloat-o-meter, lto: handle gcc LTO [45/46] kasan, lto: remove extra BUILD_BUG() in memory_is_poisoned [46/46] x86, lto: Finally enable gcc LTO for x86

Commit Message

Jiri Slaby Nov. 14, 2022, 11:43 a.m. UTC

  From: Jiri Slaby <jslaby@suse.cz>

__global_on_lto is defined as "globl" when gcc LTO is turned on (see
later patches), and "local" otherwise. It is needed for top-level
symbols which are referenced in assembly. It is because the assembly and
the symbol can each end up in a different file with gcc LTO. And that
leads to linker errors.

So the symbols have to be global when gcc LTO is in charge. On the
contrary, they can remain local on non-gcc-LTO builds.

Cc: Martin Liska <mliska@suse.cz>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 include/linux/compiler.h | 2 ++
 1 file changed, 2 insertions(+)

diff mbox series

Patch

diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index 2305a3cbe99c..16e4c1de14c4 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -135,8 +135,10 @@  void ftrace_likely_update(struct ftrace_likely_data *f, int val,
 
 #ifdef CONFIG_LTO_GCC
 # define __visible_on_lto		__visible
+# define __global_on_lto		"globl"
 #else
 # define __visible_on_lto		static
+# define __global_on_lto		"local"
 #endif
 
 #ifndef unreachable