4b058c9f28
For gettimeofday, -ffixed-r30 was passed to work around a bug in Go
code, where the vDSO trampoline forgot to save and restore this register
across function calls. But Go requires a different trampoline for every
call, and there's no reason that new Go code needs to be broken and add
more bugs. So remove -ffixed-r30 for getrandom.
Fixes: 8072b39c3a ("powerpc/vdso: Wire up getrandom() vDSO implementation on VDSO64")
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20240925175021.1526936-2-Jason@zx2c4.com
4.9 KiB
SPDX-License-Identifier: GPL-2.0
List of files in the vdso, has to be asm only for now
Include the generic Makefile to check the built vdso.
include $(srctree)/lib/vdso/Makefile
obj-vdso32 = sigtramp32-32.o gettimeofday-32.o datapage-32.o cacheflush-32.o note-32.o getcpu-32.o obj-vdso64 = sigtramp64-64.o gettimeofday-64.o datapage-64.o cacheflush-64.o note-64.o getcpu-64.o
obj-vdso32 += getrandom-32.o vgetrandom-chacha-32.o obj-vdso64 += getrandom-64.o vgetrandom-chacha-64.o
ifneq ($(c-gettimeofday-y),) CFLAGS_vgettimeofday-32.o += -include $(c-gettimeofday-y)
Go prior to 1.16.x assumes r30 is not clobbered by any VDSO code. That used to be true
by accident when the VDSO was hand-written asm code, but may not be now that the VDSO is
compiler generated. To avoid breaking Go tell GCC not to use r30. Impact on code
generation is minimal, it will just use r29 instead.
CFLAGS_vgettimeofday-64.o += -include $(c-gettimeofday-y) $(call cc-option, -ffixed-r30) endif
ifneq ($(c-getrandom-y),) CFLAGS_vgetrandom-32.o += -include $(c-getrandom-y) CFLAGS_vgetrandom-64.o += -include $(c-getrandom-y) endif
Build rules
ifdef CROSS32_COMPILE VDSOCC := $(CROSS32_COMPILE)gcc else VDSOCC := $(CC) endif
targets := $(obj-vdso32) vdso32.so.dbg vgettimeofday-32.o vgetrandom-32.o targets += crtsavres-32.o obj-vdso32 := $(addprefix $(obj)/, $(obj-vdso32)) targets += $(obj-vdso64) vdso64.so.dbg vgettimeofday-64.o vgetrandom-64.o obj-vdso64 := $(addprefix $(obj)/, $(obj-vdso64))
ccflags-y := -fno-common -fno-builtin -DBUILD_VDSO ccflags-y += $(DISABLE_LATENT_ENTROPY_PLUGIN) ccflags-y += $(call cc-option, -fno-stack-protector) ccflags-y += -DDISABLE_BRANCH_PROFILING ccflags-y += -ffreestanding -fasynchronous-unwind-tables ccflags-remove-y := $(CC_FLAGS_FTRACE) ldflags-y := -Wl,--hash-style=both -nostdlib -shared -z noexecstack $(CLANG_FLAGS) ldflags-$(CONFIG_LD_IS_LLD) += $(call cc-option,--ld-path=$(LD),-fuse-ld=lld) ldflags-$(CONFIG_LD_ORPHAN_WARN) += -Wl,--orphan-handling=$(CONFIG_LD_ORPHAN_WARN_LEVEL)
Filter flags that clang will warn are unused for linking
ldflags-y += $(filter-out $(CC_AUTO_VAR_INIT_ZERO_ENABLER) $(CC_FLAGS_FTRACE) -Wa$(comma)%, $(KBUILD_CFLAGS))
CC32FLAGS := -m32 CC32FLAGSREMOVE := -mcmodel=medium -mabi=elfv1 -mabi=elfv2 -mcall-aixdesc
This flag is supported by clang for 64-bit but not 32-bit so it will cause
an unused command line flag warning for this file.
ifdef CONFIG_CC_IS_CLANG CC32FLAGSREMOVE += -fno-stack-clash-protection endif LD32FLAGS := -Wl,-soname=linux-vdso32.so.1 AS32FLAGS := -D__VDSO32__
LD64FLAGS := -Wl,-soname=linux-vdso64.so.1 AS64FLAGS := -D__VDSO64__
targets += vdso32.lds CPPFLAGS_vdso32.lds += -P -C -Upowerpc targets += vdso64.lds CPPFLAGS_vdso64.lds += -P -C
link rule for the .so file, .lds has to be first
$(obj)/vdso32.so.dbg: $(obj)/vdso32.lds $(obj-vdso32) $(obj)/vgettimeofday-32.o $(obj)/vgetrandom-32.o $(obj)/crtsavres-32.o FORCE $(call if_changed,vdso32ld_and_check) $(obj)/vdso64.so.dbg: $(obj)/vdso64.lds $(obj-vdso64) $(obj)/vgettimeofday-64.o $(obj)/vgetrandom-64.o FORCE $(call if_changed,vdso64ld_and_check)
assembly rules for the .S files
$(obj-vdso32): %-32.o: %.S FORCE $(call if_changed_dep,vdso32as) $(obj)/crtsavres-32.o: %-32.o: $(srctree)/arch/powerpc/lib/crtsavres.S FORCE $(call if_changed_dep,vdso32as) $(obj)/vgettimeofday-32.o: %-32.o: %.c FORCE $(call if_changed_dep,vdso32cc) $(obj)/vgetrandom-32.o: %-32.o: %.c FORCE $(call if_changed_dep,vdso32cc) $(obj-vdso64): %-64.o: %.S FORCE $(call if_changed_dep,vdso64as) $(obj)/vgettimeofday-64.o: %-64.o: %.c FORCE $(call if_changed_dep,cc_o_c) $(obj)/vgetrandom-64.o: %-64.o: %.c FORCE $(call if_changed_dep,cc_o_c)
Generate VDSO offsets using helper script
gen-vdso32sym := $(src)/gen_vdso32_offsets.sh quiet_cmd_vdso32sym = VDSO32SYM $@ cmd_vdso32sym = $(NM) $< | $(gen-vdso32sym) | LC_ALL=C sort > $@ gen-vdso64sym := $(src)/gen_vdso64_offsets.sh quiet_cmd_vdso64sym = VDSO64SYM $@ cmd_vdso64sym = $(NM) $< | $(gen-vdso64sym) | LC_ALL=C sort > $@
include/generated/vdso32-offsets.h: $(obj)/vdso32.so.dbg FORCE $(call if_changed,vdso32sym) include/generated/vdso64-offsets.h: $(obj)/vdso64.so.dbg FORCE $(call if_changed,vdso64sym)
actual build commands
quiet_cmd_vdso32ld_and_check = VDSO32L $@ cmd_vdso32ld_and_check = $(VDSOCC) $(ldflags-y) $(CC32FLAGS) $(LD32FLAGS) -o $@ -Wl,-T$(filter %.lds,$^) $(filter %.o,$^); $(cmd_vdso_check) quiet_cmd_vdso32as = VDSO32A $@ cmd_vdso32as = $(VDSOCC) $(a_flags) $(CC32FLAGS) $(AS32FLAGS) -c -o $@ $< quiet_cmd_vdso32cc = VDSO32C $@ cmd_vdso32cc = $(VDSOCC) $(filter-out $(CC32FLAGSREMOVE), $(c_flags)) $(CC32FLAGS) -c -o $@ $<
quiet_cmd_vdso64ld_and_check = VDSO64L $@ cmd_vdso64ld_and_check = $(VDSOCC) $(ldflags-y) $(LD64FLAGS) -o $@ -Wl,-T$(filter %.lds,$^) $(filter %.o,$^); $(cmd_vdso_check) quiet_cmd_vdso64as = VDSO64A $@ cmd_vdso64as = $(VDSOCC) $(a_flags) $(AS64FLAGS) -c -o $@ $<