[PATCH V12 16/20] riscv: compat: vdso: Add COMPAT_VDSO base code implementation

From: guoren
Date: Tue Apr 05 2022 - 03:17:11 EST

From: Guo Ren <guoren@xxxxxxxxxxxxxxxxx>

There is no vgettimeofday supported in rv32 that makes simple to
generate rv32 vdso code which only needs riscv64 compiler. Other
architectures need change compiler or -m (machine parameter) to
support vdso32 compiling. If rv32 support vgettimeofday (which
cause C compile) in future, we would add CROSS_COMPILE to support
that makes more requirement on compiler enviornment.

linux-rv64/arch/riscv/kernel/compat_vdso/compat_vdso.so.dbg:
file format elf64-littleriscv

Disassembly of section .text:

0000000000000800 <__vdso_rt_sigreturn>:
800: 08b00893 li a7,139
804: 00000073 ecall
808: 0000 unimp
...

000000000000080c <__vdso_getcpu>:
80c: 0a800893 li a7,168
810: 00000073 ecall
814: 8082 ret
...

0000000000000818 <__vdso_flush_icache>:
818: 10300893 li a7,259
81c: 00000073 ecall
820: 8082 ret

linux-rv32/arch/riscv/kernel/vdso/vdso.so.dbg:
file format elf32-littleriscv

Disassembly of section .text:

00000800 <__vdso_rt_sigreturn>:
800: 08b00893 li a7,139
804: 00000073 ecall
808: 0000 unimp
...

0000080c <__vdso_getcpu>:
80c: 0a800893 li a7,168
810: 00000073 ecall
814: 8082 ret
...

00000818 <__vdso_flush_icache>:
818: 10300893 li a7,259
81c: 00000073 ecall
820: 8082 ret

Finally, reuse all *.S from vdso in compat_vdso that makes
implementation clear and readable.

Signed-off-by: Guo Ren <guoren@xxxxxxxxxxxxxxxxx>
Signed-off-by: Guo Ren <guoren@xxxxxxxxxx>
Tested-by: Heiko Stuebner <heiko@xxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Palmer Dabbelt <palmer@xxxxxxxxxxx>
---
arch/riscv/Makefile | 5 ++
arch/riscv/include/asm/vdso.h | 9 +++
arch/riscv/kernel/Makefile | 1 +
arch/riscv/kernel/compat_vdso/.gitignore | 2 +
arch/riscv/kernel/compat_vdso/Makefile | 78 +++++++++++++++++++
arch/riscv/kernel/compat_vdso/compat_vdso.S | 8 ++
.../kernel/compat_vdso/compat_vdso.lds.S | 3 +
arch/riscv/kernel/compat_vdso/flush_icache.S | 3 +
.../compat_vdso/gen_compat_vdso_offsets.sh | 5 ++
arch/riscv/kernel/compat_vdso/getcpu.S | 3 +
arch/riscv/kernel/compat_vdso/note.S | 3 +
arch/riscv/kernel/compat_vdso/rt_sigreturn.S | 3 +
arch/riscv/kernel/vdso/vdso.S | 6 +-
13 files changed, 128 insertions(+), 1 deletion(-)
create mode 100644 arch/riscv/kernel/compat_vdso/.gitignore
create mode 100644 arch/riscv/kernel/compat_vdso/Makefile
create mode 100644 arch/riscv/kernel/compat_vdso/compat_vdso.S
create mode 100644 arch/riscv/kernel/compat_vdso/compat_vdso.lds.S
create mode 100644 arch/riscv/kernel/compat_vdso/flush_icache.S
create mode 100755 arch/riscv/kernel/compat_vdso/gen_compat_vdso_offsets.sh
create mode 100644 arch/riscv/kernel/compat_vdso/getcpu.S
create mode 100644 arch/riscv/kernel/compat_vdso/note.S
create mode 100644 arch/riscv/kernel/compat_vdso/rt_sigreturn.S

diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile
index c6ca1b9cbf71..6a494029b8bd 100644
--- a/arch/riscv/Makefile
+++ b/arch/riscv/Makefile
@@ -112,12 +112,17 @@ libs-$(CONFIG_EFI_STUB) += $(objtree)/drivers/firmware/efi/libstub/lib.a
PHONY += vdso_install
vdso_install:
$(Q)$(MAKE) $(build)=arch/riscv/kernel/vdso $@
+ $(if $(CONFIG_COMPAT),$(Q)$(MAKE) \
+ $(build)=arch/riscv/kernel/compat_vdso $@)

ifeq ($(KBUILD_EXTMOD),)
ifeq ($(CONFIG_MMU),y)
prepare: vdso_prepare
vdso_prepare: prepare0
$(Q)$(MAKE) $(build)=arch/riscv/kernel/vdso include/generated/vdso-offsets.h
+ $(if $(CONFIG_COMPAT),$(Q)$(MAKE) \
+ $(build)=arch/riscv/kernel/compat_vdso include/generated/compat_vdso-offsets.h)
+
endif
endif

diff --git a/arch/riscv/include/asm/vdso.h b/arch/riscv/include/asm/vdso.h
index bc6f75f3a199..af981426fe0f 100644
--- a/arch/riscv/include/asm/vdso.h
+++ b/arch/riscv/include/asm/vdso.h
@@ -21,6 +21,15 @@

#define VDSO_SYMBOL(base, name) \
(void __user *)((unsigned long)(base) + __vdso_##name##_offset)
+
+#ifdef CONFIG_COMPAT
+#include <generated/compat_vdso-offsets.h>
+
+#define COMPAT_VDSO_SYMBOL(base, name) \
+ (void __user *)((unsigned long)(base) + compat__vdso_##name##_offset)
+
+#endif /* CONFIG_COMPAT */
+
#endif /* !__ASSEMBLY__ */

#endif /* CONFIG_MMU */
diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile
index 2fa06d6572bb..fec77d101f9e 100644
--- a/arch/riscv/kernel/Makefile
+++ b/arch/riscv/kernel/Makefile
@@ -70,3 +70,4 @@ obj-$(CONFIG_JUMP_LABEL) += jump_label.o

obj-$(CONFIG_EFI) += efi.o
obj-$(CONFIG_COMPAT) += compat_syscall_table.o
+obj-$(CONFIG_COMPAT) += compat_vdso/
diff --git a/arch/riscv/kernel/compat_vdso/.gitignore b/arch/riscv/kernel/compat_vdso/.gitignore
new file mode 100644
index 000000000000..19d83d846c1e
--- /dev/null
+++ b/arch/riscv/kernel/compat_vdso/.gitignore
@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: GPL-2.0-only
+compat_vdso.lds
diff --git a/arch/riscv/kernel/compat_vdso/Makefile b/arch/riscv/kernel/compat_vdso/Makefile
new file mode 100644
index 000000000000..260daf3236d3
--- /dev/null
+++ b/arch/riscv/kernel/compat_vdso/Makefile
@@ -0,0 +1,78 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Makefile for compat_vdso
+#
+
+# Symbols present in the compat_vdso
+compat_vdso-syms = rt_sigreturn
+compat_vdso-syms += getcpu
+compat_vdso-syms += flush_icache
+
+COMPAT_CC := $(CC)
+COMPAT_LD := $(LD)
+
+COMPAT_CC_FLAGS := -march=rv32g -mabi=ilp32
+COMPAT_LD_FLAGS := -melf32lriscv
+
+# Files to link into the compat_vdso
+obj-compat_vdso = $(patsubst %, %.o, $(compat_vdso-syms)) note.o
+
+# Build rules
+targets := $(obj-compat_vdso) compat_vdso.so compat_vdso.so.dbg compat_vdso.lds
+obj-compat_vdso := $(addprefix $(obj)/, $(obj-compat_vdso))
+
+obj-y += compat_vdso.o
+CPPFLAGS_compat_vdso.lds += -P -C -U$(ARCH)
+
+# Disable profiling and instrumentation for VDSO code
+GCOV_PROFILE := n
+KCOV_INSTRUMENT := n
+KASAN_SANITIZE := n
+UBSAN_SANITIZE := n
+
+# Force dependency
+$(obj)/compat_vdso.o: $(obj)/compat_vdso.so
+
+# link rule for the .so file, .lds has to be first
+$(obj)/compat_vdso.so.dbg: $(obj)/compat_vdso.lds $(obj-compat_vdso) FORCE
+ $(call if_changed,compat_vdsold)
+LDFLAGS_compat_vdso.so.dbg = -shared -S -soname=linux-compat_vdso.so.1 \
+ --build-id=sha1 --hash-style=both --eh-frame-hdr
+
+$(obj-compat_vdso): %.o: %.S FORCE
+ $(call if_changed_dep,compat_vdsoas)
+
+# strip rule for the .so file
+$(obj)/%.so: OBJCOPYFLAGS := -S
+$(obj)/%.so: $(obj)/%.so.dbg FORCE
+ $(call if_changed,objcopy)
+
+# Generate VDSO offsets using helper script
+gen-compat_vdsosym := $(srctree)/$(src)/gen_compat_vdso_offsets.sh
+quiet_cmd_compat_vdsosym = VDSOSYM $@
+ cmd_compat_vdsosym = $(NM) $< | $(gen-compat_vdsosym) | LC_ALL=C sort > $@
+
+include/generated/compat_vdso-offsets.h: $(obj)/compat_vdso.so.dbg FORCE
+ $(call if_changed,compat_vdsosym)
+
+# actual build commands
+# The DSO images are built using a special linker script
+# Make sure only to export the intended __compat_vdso_xxx symbol offsets.
+quiet_cmd_compat_vdsold = VDSOLD $@
+ cmd_compat_vdsold = $(COMPAT_LD) $(ld_flags) $(COMPAT_LD_FLAGS) -T $(filter-out FORCE,$^) -o $@.tmp && \
+ $(OBJCOPY) $(patsubst %, -G __compat_vdso_%, $(compat_vdso-syms)) $@.tmp $@ && \
+ rm $@.tmp
+
+# actual build commands
+quiet_cmd_compat_vdsoas = VDSOAS $@
+ cmd_compat_vdsoas = $(COMPAT_CC) $(a_flags) $(COMPAT_CC_FLAGS) -c -o $@ $<
+
+# install commands for the unstripped file
+quiet_cmd_compat_vdso_install = INSTALL $@
+ cmd_compat_vdso_install = cp $(obj)/$@.dbg $(MODLIB)/compat_vdso/$@
+
+compat_vdso.so: $(obj)/compat_vdso.so.dbg
+ @mkdir -p $(MODLIB)/compat_vdso
+ $(call cmd,compat_vdso_install)
+
+compat_vdso_install: compat_vdso.so
diff --git a/arch/riscv/kernel/compat_vdso/compat_vdso.S b/arch/riscv/kernel/compat_vdso/compat_vdso.S
new file mode 100644
index 000000000000..ffd66237e091
--- /dev/null
+++ b/arch/riscv/kernel/compat_vdso/compat_vdso.S
@@ -0,0 +1,8 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#define vdso_start compat_vdso_start
+#define vdso_end compat_vdso_end
+
+#define __VDSO_PATH "arch/riscv/kernel/compat_vdso/compat_vdso.so"
+
+#include "../vdso/vdso.S"
diff --git a/arch/riscv/kernel/compat_vdso/compat_vdso.lds.S b/arch/riscv/kernel/compat_vdso/compat_vdso.lds.S
new file mode 100644
index 000000000000..c7c9355d311e
--- /dev/null
+++ b/arch/riscv/kernel/compat_vdso/compat_vdso.lds.S
@@ -0,0 +1,3 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#include "../vdso/vdso.lds.S"
diff --git a/arch/riscv/kernel/compat_vdso/flush_icache.S b/arch/riscv/kernel/compat_vdso/flush_icache.S
new file mode 100644
index 000000000000..523dd8b96045
--- /dev/null
+++ b/arch/riscv/kernel/compat_vdso/flush_icache.S
@@ -0,0 +1,3 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#include "../vdso/flush_icache.S"
diff --git a/arch/riscv/kernel/compat_vdso/gen_compat_vdso_offsets.sh b/arch/riscv/kernel/compat_vdso/gen_compat_vdso_offsets.sh
new file mode 100755
index 000000000000..8ac070c783b3
--- /dev/null
+++ b/arch/riscv/kernel/compat_vdso/gen_compat_vdso_offsets.sh
@@ -0,0 +1,5 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+
+LC_ALL=C
+sed -n -e 's/^[0]\+\(0[0-9a-fA-F]*\) . \(__vdso_[a-zA-Z0-9_]*\)$/\#define compat\2_offset\t0x\1/p'
diff --git a/arch/riscv/kernel/compat_vdso/getcpu.S b/arch/riscv/kernel/compat_vdso/getcpu.S
new file mode 100644
index 000000000000..10f463efe271
--- /dev/null
+++ b/arch/riscv/kernel/compat_vdso/getcpu.S
@@ -0,0 +1,3 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#include "../vdso/getcpu.S"
diff --git a/arch/riscv/kernel/compat_vdso/note.S b/arch/riscv/kernel/compat_vdso/note.S
new file mode 100644
index 000000000000..b10312907542
--- /dev/null
+++ b/arch/riscv/kernel/compat_vdso/note.S
@@ -0,0 +1,3 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#include "../vdso/note.S"
diff --git a/arch/riscv/kernel/compat_vdso/rt_sigreturn.S b/arch/riscv/kernel/compat_vdso/rt_sigreturn.S
new file mode 100644
index 000000000000..884aada4facc
--- /dev/null
+++ b/arch/riscv/kernel/compat_vdso/rt_sigreturn.S
@@ -0,0 +1,3 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#include "../vdso/rt_sigreturn.S"
diff --git a/arch/riscv/kernel/vdso/vdso.S b/arch/riscv/kernel/vdso/vdso.S
index df222245be05..83f1c899e8d8 100644
--- a/arch/riscv/kernel/vdso/vdso.S
+++ b/arch/riscv/kernel/vdso/vdso.S
@@ -7,12 +7,16 @@
#include <linux/linkage.h>
#include <asm/page.h>

+#ifndef __VDSO_PATH
+#define __VDSO_PATH "arch/riscv/kernel/vdso/vdso.so"
+#endif
+
__PAGE_ALIGNED_DATA

.globl vdso_start, vdso_end
.balign PAGE_SIZE
vdso_start:
- .incbin "arch/riscv/kernel/vdso/vdso.so"
+ .incbin __VDSO_PATH
.balign PAGE_SIZE
vdso_end:

--
2.25.1