Patch "RISC-V: Fix VDSO build for !MMU" has been added to the 5.14-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    RISC-V: Fix VDSO build for !MMU

to the 5.14-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     risc-v-fix-vdso-build-for-mmu.patch
and it can be found in the queue-5.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit bd218da2e057f703733b20e0fc6aac634859d12c
Author: Palmer Dabbelt <palmerdabbelt@xxxxxxxxxx>
Date:   Wed Aug 25 22:52:45 2021 -0700

    RISC-V: Fix VDSO build for !MMU
    
    [ Upstream commit a290f510a178830a01bfc06e66a54bbe4ece5d2a ]
    
    We don't have a VDSO for the !MMU configurations, so don't try to build
    one.
    
    Fixes: fde9c59aebaf ("riscv: explicitly use symbol offsets for VDSO")
    Signed-off-by: Palmer Dabbelt <palmerdabbelt@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile
index e026b2d0a5a4..83ee0e71204c 100644
--- a/arch/riscv/Makefile
+++ b/arch/riscv/Makefile
@@ -108,9 +108,11 @@ PHONY += vdso_install
 vdso_install:
 	$(Q)$(MAKE) $(build)=arch/riscv/kernel/vdso $@
 
+ifeq ($(CONFIG_MMU),y)
 prepare: vdso_prepare
 vdso_prepare: prepare0
 	$(Q)$(MAKE) $(build)=arch/riscv/kernel/vdso include/generated/vdso-offsets.h
+endif
 
 ifneq ($(CONFIG_XIP_KERNEL),y)
 ifeq ($(CONFIG_RISCV_M_MODE)$(CONFIG_SOC_CANAAN),yy)
diff --git a/arch/riscv/include/asm/vdso.h b/arch/riscv/include/asm/vdso.h
index d8d003c2b5a3..893e47195e30 100644
--- a/arch/riscv/include/asm/vdso.h
+++ b/arch/riscv/include/asm/vdso.h
@@ -8,6 +8,13 @@
 #ifndef _ASM_RISCV_VDSO_H
 #define _ASM_RISCV_VDSO_H
 
+
+/*
+ * All systems with an MMU have a VDSO, but systems without an MMU don't
+ * support shared libraries and therefor don't have one.
+ */
+#ifdef CONFIG_MMU
+
 #include <linux/types.h>
 #include <generated/vdso-offsets.h>
 
@@ -19,6 +26,8 @@ struct vdso_data {
 #define VDSO_SYMBOL(base, name)							\
 	(void __user *)((unsigned long)(base) + __vdso_##name##_offset)
 
+#endif /* CONFIG_MMU */
+
 asmlinkage long sys_riscv_flush_icache(uintptr_t, uintptr_t, uintptr_t);
 
 #endif /* _ASM_RISCV_VDSO_H */