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921ebd8f2c
Despite RISC-V having a direct 'fence.i' instruction available to userspace (which we can't trap!), that's not actually viable when running on Linux because the kernel might schedule a process on another hart. There is no way for userspace to handle this without invoking the kernel (as it doesn't know the thread->hart mappings), so we've defined a RISC-V specific system call to flush the instruction cache. This patch adds both a system call and a VDSO entry. If possible, we'd like to avoid having the system call be considered part of the user-facing ABI and instead restrict that to the VDSO entry -- both just in general to avoid having additional user-visible ABI to maintain, and because we'd prefer that users just call the VDSO entry because there might be a better way to do this in the future (ie, one that doesn't require entering the kernel). Signed-off-by: Andrew Waterman <andrew@sifive.com> Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
69 lines
2.2 KiB
Makefile
69 lines
2.2 KiB
Makefile
# Copied from arch/tile/kernel/vdso/Makefile
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# Symbols present in the vdso
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vdso-syms = rt_sigreturn
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vdso-syms += gettimeofday
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vdso-syms += clock_gettime
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vdso-syms += clock_getres
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vdso-syms += getcpu
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vdso-syms += flush_icache
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# Files to link into the vdso
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obj-vdso = $(patsubst %, %.o, $(vdso-syms))
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# Build rules
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targets := $(obj-vdso) vdso.so vdso.so.dbg vdso.lds vdso-dummy.o
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obj-vdso := $(addprefix $(obj)/, $(obj-vdso))
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obj-y += vdso.o vdso-syms.o
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CPPFLAGS_vdso.lds += -P -C -U$(ARCH)
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# Disable gcov profiling for VDSO code
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GCOV_PROFILE := n
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# Force dependency
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$(obj)/vdso.o: $(obj)/vdso.so
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# link rule for the .so file, .lds has to be first
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SYSCFLAGS_vdso.so.dbg = $(c_flags)
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$(obj)/vdso.so.dbg: $(src)/vdso.lds $(obj-vdso) FORCE
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$(call if_changed,vdsold)
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# We also create a special relocatable object that should mirror the symbol
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# table and layout of the linked DSO. With ld -R we can then refer to
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# these symbols in the kernel code rather than hand-coded addresses.
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SYSCFLAGS_vdso.so.dbg = -shared -s -Wl,-soname=linux-vdso.so.1 \
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$(call cc-ldoption, -Wl$(comma)--hash-style=both)
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$(obj)/vdso-dummy.o: $(src)/vdso.lds $(obj)/rt_sigreturn.o FORCE
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$(call if_changed,vdsold)
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LDFLAGS_vdso-syms.o := -r -R
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$(obj)/vdso-syms.o: $(obj)/vdso-dummy.o FORCE
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$(call if_changed,ld)
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# strip rule for the .so file
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$(obj)/%.so: OBJCOPYFLAGS := -S
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$(obj)/%.so: $(obj)/%.so.dbg FORCE
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$(call if_changed,objcopy)
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# actual build commands
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# The DSO images are built using a special linker script
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# Add -lgcc so rv32 gets static muldi3 and lshrdi3 definitions.
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# Make sure only to export the intended __vdso_xxx symbol offsets.
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quiet_cmd_vdsold = VDSOLD $@
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cmd_vdsold = $(CC) $(KCFLAGS) -nostdlib $(SYSCFLAGS_$(@F)) \
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-Wl,-T,$(filter-out FORCE,$^) -o $@.tmp -lgcc && \
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$(CROSS_COMPILE)objcopy \
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$(patsubst %, -G __vdso_%, $(vdso-syms)) $@.tmp $@
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# install commands for the unstripped file
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quiet_cmd_vdso_install = INSTALL $@
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cmd_vdso_install = cp $(obj)/$@.dbg $(MODLIB)/vdso/$@
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vdso.so: $(obj)/vdso.so.dbg
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@mkdir -p $(MODLIB)/vdso
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$(call cmd,vdso_install)
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vdso_install: vdso.so
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