mirror of
git://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs.git
synced 2026-10-30 22:03:17 +01:00
Nathan Chancellor
eb13a1ff27
After a recent change in LLVM [1], builds with the random vDSO implementation, such as PowerPC and RISC-V, fail when checking the vDSO: arch/powerpc/kernel/vdso/vdso32.so.dbg: dynamic relocations are not supported arch/riscv/kernel/vdso/vdso.so.dbg: dynamic relocations are not supported memset() is now generated when zeroing params->reserved for some builds because LLVM has an optimization (now run in more instances) that can recognize at compile time when it is assigning a static value to a contiguous area of memory and turn that into a call to memset(). Both clang and GCC assume memset() is always available [2]. Clang has an internal fiddly hook, -max-store-memset, which we can set to a high number, to disable generating out of line memset calls [3]. Similarly, GCC has -finline-stringops=memset to do the same [4], should this issue ever hit future version of GCC. While these options wouldn't make sense for normal kernel code, it is fine for the extremely limited and intentionally compact vDSO code. Link: https://github.com/llvm/llvm-project/commit/90cebef1411617fc3eedd359bdf00cb44b1c2439 [1] Link: https://gcc.gnu.org/onlinedocs/gcc-16.2.0/gcc/Standards.html#index-ffreestanding [2] Link: https://github.com/llvm/llvm-project/commit/b28eeb28bea39148738dc375e8a97072a1907e64 [3] Link: https://gcc.gnu.org/onlinedocs/gcc/Optimize-Options.html#index-finline-stringops [4] Closes: https://github.com/ClangBuiltLinux/linux/issues/2183 Cc: [email protected] # v6.12+ Signed-off-by: Nathan Chancellor <[email protected]> Signed-off-by: Jason A. Donenfeld <[email protected]>
131 lines
5.6 KiB
Makefile
131 lines
5.6 KiB
Makefile
# SPDX-License-Identifier: GPL-2.0
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# List of files in the vdso, has to be asm only for now
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# Include the generic Makefile to check the built vdso.
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include $(srctree)/lib/vdso/Makefile.include
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obj-vdso32 = sigtramp32-32.o gettimeofday-32.o datapage-32.o cacheflush-32.o note-32.o getcpu-32.o
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obj-vdso64 = sigtramp64-64.o gettimeofday-64.o datapage-64.o cacheflush-64.o note-64.o getcpu-64.o
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obj-vdso32 += getrandom-32.o vgetrandom-chacha-32.o
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obj-vdso64 += getrandom-64.o vgetrandom-chacha-64.o
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ifneq ($(c-gettimeofday-y),)
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CFLAGS_vgettimeofday-32.o += -include $(c-gettimeofday-y)
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# Go prior to 1.16.x assumes r30 is not clobbered by any VDSO code. That used to be true
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# by accident when the VDSO was hand-written asm code, but may not be now that the VDSO is
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# compiler generated. To avoid breaking Go tell GCC not to use r30. Impact on code
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# generation is minimal, it will just use r29 instead.
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CFLAGS_vgettimeofday-64.o += -include $(c-gettimeofday-y) $(call cc-option, -ffixed-r30)
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endif
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ifneq ($(c-getrandom-y),)
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CFLAGS_vgetrandom-32.o += -include $(c-getrandom-y)
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CFLAGS_vgetrandom-64.o += -include $(c-getrandom-y)
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endif
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# Build rules
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ifdef CROSS32_COMPILE
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VDSOCC := $(CROSS32_COMPILE)gcc
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else
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VDSOCC := $(CC)
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endif
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targets := $(obj-vdso32) vdso32.so.dbg vgettimeofday-32.o vgetrandom-32.o
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targets += crtsavres-32.o
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obj-vdso32 := $(addprefix $(obj)/, $(obj-vdso32))
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targets += $(obj-vdso64) vdso64.so.dbg vgettimeofday-64.o vgetrandom-64.o
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obj-vdso64 := $(addprefix $(obj)/, $(obj-vdso64))
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ccflags-y := -fno-common -fno-builtin -DBUILD_VDSO
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ccflags-y += $(DISABLE_LATENT_ENTROPY_PLUGIN)
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ccflags-y += $(call cc-option, -fno-stack-protector)
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ccflags-y += -DDISABLE_BRANCH_PROFILING
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ccflags-y += $(CONFIG_CC_OPT_INLINE_MEMSET)
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ccflags-y += -ffreestanding -fasynchronous-unwind-tables
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ccflags-remove-y := $(CC_FLAGS_FTRACE)
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ldflags-y := -Wl,--hash-style=both -nostdlib -shared -z noexecstack $(CLANG_FLAGS)
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ldflags-$(CONFIG_LD_IS_LLD) += $(call cc-option,--ld-path=$(LD),-fuse-ld=lld)
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ldflags-$(CONFIG_LD_ORPHAN_WARN) += -Wl,--orphan-handling=$(CONFIG_LD_ORPHAN_WARN_LEVEL)
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# Filter flags that clang will warn are unused for linking
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ldflags-y += $(filter-out $(CC_AUTO_VAR_INIT_ZERO_ENABLER) $(CC_FLAGS_FTRACE) -Wa$(comma)%, $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS))
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CC32FLAGS := -m32
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CC32FLAGSREMOVE := -mcmodel=medium -mabi=elfv1 -mabi=elfv2 -mcall-aixdesc -mpcrel
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ifdef CONFIG_CC_IS_CLANG
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# This flag is supported by clang for 64-bit but not 32-bit so it will cause
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# an unused command line flag warning for this file.
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CC32FLAGSREMOVE += -fno-stack-clash-protection
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# -mstack-protector-guard values from the 64-bit build are not valid for the
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# 32-bit one. clang validates the values passed to these arguments during
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# parsing, even when -fno-stack-protector is passed afterwards.
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CC32FLAGSREMOVE += -mstack-protector-guard%
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# ftrace is disabled for the vdso but arch/powerpc/Makefile adds this define to
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# KBUILD_CPPFLAGS, which enables use of the 'patchable_function_entry'
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# attribute in the 'inline' define via 'notrace'. This attribute is not
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# supported for the powerpcle target, resulting in many instances of
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# -Wunknown-attributes.
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CC32FLAGSREMOVE += -DCC_USING_PATCHABLE_FUNCTION_ENTRY
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endif
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LD32FLAGS := -Wl,-soname=linux-vdso32.so.1
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AS32FLAGS := -D__VDSO32__
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LD64FLAGS := -Wl,-soname=linux-vdso64.so.1
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AS64FLAGS := -D__VDSO64__
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targets += vdso32.lds
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CPPFLAGS_vdso32.lds += -P -C -Upowerpc
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targets += vdso64.lds
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CPPFLAGS_vdso64.lds += -P -C
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# link rule for the .so file, .lds has to be first
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$(obj)/vdso32.so.dbg: $(obj)/vdso32.lds $(obj-vdso32) $(obj)/vgettimeofday-32.o $(obj)/vgetrandom-32.o $(obj)/crtsavres-32.o FORCE
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$(call if_changed,vdso32ld_and_check)
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$(obj)/vdso64.so.dbg: $(obj)/vdso64.lds $(obj-vdso64) $(obj)/vgettimeofday-64.o $(obj)/vgetrandom-64.o FORCE
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$(call if_changed,vdso64ld_and_check)
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# assembly rules for the .S files
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$(obj-vdso32): %-32.o: %.S FORCE
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$(call if_changed_dep,vdso32as)
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$(obj)/crtsavres-32.o: %-32.o: $(srctree)/arch/powerpc/lib/crtsavres.S FORCE
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$(call if_changed_dep,vdso32as)
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$(obj)/vgettimeofday-32.o: %-32.o: %.c FORCE
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$(call if_changed_dep,vdso32cc)
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$(obj)/vgetrandom-32.o: %-32.o: %.c FORCE
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$(call if_changed_dep,vdso32cc)
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$(obj-vdso64): %-64.o: %.S FORCE
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$(call if_changed_dep,vdso64as)
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$(obj)/vgettimeofday-64.o: %-64.o: %.c FORCE
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$(call if_changed_dep,cc_o_c)
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$(obj)/vgetrandom-64.o: %-64.o: %.c FORCE
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$(call if_changed_dep,cc_o_c)
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# Generate VDSO offsets using helper script
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gen-vdso32sym := $(src)/gen_vdso32_offsets.sh
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quiet_cmd_vdso32sym = VDSO32SYM $@
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cmd_vdso32sym = $(NM) $< | $(gen-vdso32sym) | LC_ALL=C sort > $@
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gen-vdso64sym := $(src)/gen_vdso64_offsets.sh
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quiet_cmd_vdso64sym = VDSO64SYM $@
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cmd_vdso64sym = $(NM) $< | $(gen-vdso64sym) | LC_ALL=C sort > $@
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include/generated/vdso32-offsets.h: $(obj)/vdso32.so.dbg FORCE
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$(call if_changed,vdso32sym)
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include/generated/vdso64-offsets.h: $(obj)/vdso64.so.dbg FORCE
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$(call if_changed,vdso64sym)
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# actual build commands
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quiet_cmd_vdso32ld_and_check = VDSO32L $@
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cmd_vdso32ld_and_check = $(VDSOCC) $(ldflags-y) $(CC32FLAGS) $(LD32FLAGS) -o $@ -Wl,-T$(filter %.lds,$^) $(filter %.o,$^); $(cmd_vdso_check)
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quiet_cmd_vdso32as = VDSO32A $@
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cmd_vdso32as = $(VDSOCC) $(a_flags) $(CC32FLAGS) $(AS32FLAGS) -c -o $@ $<
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quiet_cmd_vdso32cc = VDSO32C $@
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cmd_vdso32cc = $(VDSOCC) $(filter-out $(CC32FLAGSREMOVE), $(c_flags)) $(CC32FLAGS) -c -o $@ $<
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quiet_cmd_vdso64ld_and_check = VDSO64L $@
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cmd_vdso64ld_and_check = $(VDSOCC) $(ldflags-y) $(LD64FLAGS) -o $@ -Wl,-T$(filter %.lds,$^) $(filter %.o,$^); $(cmd_vdso_check)
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quiet_cmd_vdso64as = VDSO64A $@
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cmd_vdso64as = $(VDSOCC) $(a_flags) $(AS64FLAGS) -c -o $@ $<
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