MIPS: Disable VDSO time functionality on microMIPS

A check we're about to add to pick up on function calls that depend on bogus use of the GOT in the VDSO picked up on instances of such function calls in microMIPS builds. Since the code appears genuinely problematic, and given the relatively small amount of use & testing that microMIPS sees, go ahead & disable the VDSO for microMIPS builds. Signed-off-by: Paul Burton <[email protected]>
kmaincent · Feb 15, 2020 · 07015d7 · 07015d7
1 parent d3f703c
commit 07015d7
Showing 1 changed file with 17 additions and 2 deletions.
diff --git a/arch/mips/vdso/Makefile b/arch/mips/vdso/Makefile
@@ -52,6 +52,8 @@ endif
 
 CFLAGS_REMOVE_vgettimeofday.o = -pg
 
+DISABLE_VDSO := n
+
 #
 # For the pre-R6 code in arch/mips/vdso/vdso.h for locating
 # the base address of VDSO, the linker will emit a R_MIPS_PC32
@@ -65,11 +67,24 @@ CFLAGS_REMOVE_vgettimeofday.o = -pg
 ifndef CONFIG_CPU_MIPSR6
   ifeq ($(call ld-ifversion, -lt, 225000000, y),y)
     $(warning MIPS VDSO requires binutils >= 2.25)
-    obj-vdso-y := $(filter-out vgettimeofday.o, $(obj-vdso-y))
-    ccflags-vdso += -DDISABLE_MIPS_VDSO
+    DISABLE_VDSO := y
   endif
 endif
 
+#
+# GCC (at least up to version 9.2) appears to emit function calls that make use
+# of the GOT when targeting microMIPS, which we can't use in the VDSO due to
+# the lack of relocations. As such, we disable the VDSO for microMIPS builds.
+#
+ifdef CONFIG_CPU_MICROMIPS
+  DISABLE_VDSO := y
+endif
+
+ifeq ($(DISABLE_VDSO),y)
+  obj-vdso-y := $(filter-out vgettimeofday.o, $(obj-vdso-y))
+  ccflags-vdso += -DDISABLE_MIPS_VDSO
+endif
+
 # VDSO linker flags.
 VDSO_LDFLAGS := \
 	-Wl,-Bsymbolic -Wl,--no-undefined -Wl,-soname=linux-vdso.so.1 \