csky: Reconstruct VDSO framework

Reconstruct vdso framework to support future vsyscall,
vgettimeofday features. These are very important features to reduce
system calls into the kernel for performance improvement.

The patch is reference RISC-V's

Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Cc: Palmer Dabbelt <palmerdabbelt@google.com>

13 files changed, 269 insertions, 89 deletions

diff --git a/arch/csky/abiv1/inc/abi/vdso.h b/arch/csky/abiv1/inc/abi/vdso.h
index 14352f524f1d..9e6d0a2fdd2b 100644
--- a/arch/csky/abiv1/inc/abi/vdso.h
+++ b/arch/csky/abiv1/inc/abi/vdso.h
@@ -1,17 +1,9 @@
 /* SPDX-License-Identifier: GPL-2.0 */
 
-#include <linux/uaccess.h>
+#ifndef __ABI_CSKY_VDSO_H
+#define __ABI_CSKY_VDSO_H
 
-static inline int setup_vdso_page(unsigned short *ptr)
-{
-	int err = 0;
+/* movi r1, 127; addi r1, (139 - 127) */
+#define SET_SYSCALL_ID	.long 0x20b167f1
 
-	/* movi r1, 127 */
-	err |= __put_user(0x67f1, ptr + 0);
-	/* addi r1, (139 - 127) */
-	err |= __put_user(0x20b1, ptr + 1);
-	/* trap 0 */
-	err |= __put_user(0x0008, ptr + 2);
-
-	return err;
-}
+#endif /* __ABI_CSKY_VDSO_H */
diff --git a/arch/csky/abiv2/inc/abi/vdso.h b/arch/csky/abiv2/inc/abi/vdso.h
index b60d4a070326..40fd10d893ff 100644
--- a/arch/csky/abiv2/inc/abi/vdso.h
+++ b/arch/csky/abiv2/inc/abi/vdso.h
@@ -3,21 +3,7 @@
 #ifndef __ABI_CSKY_VDSO_H
 #define __ABI_CSKY_VDSO_H
 
-#include <linux/uaccess.h>
+/* movi r7, 173 */
+#define SET_SYSCALL_ID	.long 0x008bea07
 
-static inline int setup_vdso_page(unsigned short *ptr)
-{
-	int err = 0;
-
-	/* movi r7, 173 */
-	err |= __put_user(0xea07, ptr);
-	err |= __put_user(0x008b,      ptr+1);
-
-	/* trap 0 */
-	err |= __put_user(0xc000,   ptr+2);
-	err |= __put_user(0x2020,   ptr+3);
-
-	return err;
-}
-
-#endif /* __ABI_CSKY_STRING_H */
+#endif /* __ABI_CSKY_VDSO_H */
diff --git a/arch/csky/include/asm/vdso.h b/arch/csky/include/asm/vdso.h
index d963d691f3a1..12c5d638e784 100644
--- a/arch/csky/include/asm/vdso.h
+++ b/arch/csky/include/asm/vdso.h
@@ -3,10 +3,23 @@
 #ifndef __ASM_CSKY_VDSO_H
 #define __ASM_CSKY_VDSO_H
 
-#include <abi/vdso.h>
+#include <linux/types.h>
 
-struct csky_vdso {
-	unsigned short rt_signal_retcode[4];
+struct vdso_data {
 };
 
+/*
+ * The VDSO symbols are mapped into Linux so we can just use regular symbol
+ * addressing to get their offsets in userspace.  The symbols are mapped at an
+ * offset of 0, but since the linker must support setting weak undefined
+ * symbols to the absolute address 0 it also happens to support other low
+ * addresses even when the code model suggests those low addresses would not
+ * otherwise be availiable.
+ */
+#define VDSO_SYMBOL(base, name)							\
+({										\
+	extern const char __vdso_##name[];					\
+	(void __user *)((unsigned long)(base) + __vdso_##name);			\
+})
+
 #endif /* __ASM_CSKY_VDSO_H */
diff --git a/arch/csky/kernel/Makefile b/arch/csky/kernel/Makefile
index 37f37c0e934a..6c0f36010ed0 100644
--- a/arch/csky/kernel/Makefile
+++ b/arch/csky/kernel/Makefile
@@ -1,7 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0-only
 extra-y := head.o vmlinux.lds
 
-obj-y += entry.o atomic.o signal.o traps.o irq.o time.o vdso.o
+obj-y += entry.o atomic.o signal.o traps.o irq.o time.o vdso.o vdso/
 obj-y += power.o syscall.o syscall_table.o setup.o
 obj-y += process.o cpu-probe.o ptrace.o stacktrace.o
 obj-y += probes/
diff --git a/arch/csky/kernel/signal.c b/arch/csky/kernel/signal.c
index 37ea64ed3c12..312f046d452d 100644
--- a/arch/csky/kernel/signal.c
+++ b/arch/csky/kernel/signal.c
@@ -134,7 +134,6 @@ setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
 {
 	struct rt_sigframe *frame;
 	int err = 0;
-	struct csky_vdso *vdso = current->mm->context.vdso;
 
 	frame = get_sigframe(ksig, regs, sizeof(*frame));
 	if (!access_ok(frame, sizeof(*frame)))
@@ -152,7 +151,8 @@ setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
 		return -EFAULT;
 
 	/* Set up to return from userspace. */
-	regs->lr = (unsigned long)(vdso->rt_signal_retcode);
+	regs->lr = (unsigned long)VDSO_SYMBOL(
+		current->mm->context.vdso, rt_sigreturn);
 
 	/*
 	 * Set up registers for signal handler.
diff --git a/arch/csky/kernel/vdso.c b/arch/csky/kernel/vdso.c
index abc3dbc658d4..839523920843 100644
--- a/arch/csky/kernel/vdso.c
+++ b/arch/csky/kernel/vdso.c
@@ -1,86 +1,103 @@
 // SPDX-License-Identifier: GPL-2.0
 // Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
 
-#include <linux/kernel.h>
-#include <linux/err.h>
-#include <linux/sched.h>
-#include <linux/mm.h>
-#include <linux/init.h>
 #include <linux/binfmts.h>
 #include <linux/elf.h>
-#include <linux/vmalloc.h>
-#include <linux/unistd.h>
-#include <linux/uaccess.h>
+#include <linux/err.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
 
+#include <asm/page.h>
 #include <asm/vdso.h>
-#include <asm/cacheflush.h>
 
-static struct page *vdso_page;
+extern char vdso_start[], vdso_end[];
 
-static int __init init_vdso(void)
-{
-	struct csky_vdso *vdso;
-	int err = 0;
-
-	vdso_page = alloc_page(GFP_KERNEL);
-	if (!vdso_page)
-		panic("Cannot allocate vdso");
+static unsigned int vdso_pages;
+static struct page **vdso_pagelist;
 
-	vdso = vmap(&vdso_page, 1, 0, PAGE_KERNEL);
-	if (!vdso)
-		panic("Cannot map vdso");
+/*
+ * The vDSO data page.
+ */
+static union {
+	struct vdso_data	data;
+	u8			page[PAGE_SIZE];
+} vdso_data_store __page_aligned_data;
+struct vdso_data *vdso_data = &vdso_data_store.data;
 
-	clear_page(vdso);
-
-	err = setup_vdso_page(vdso->rt_signal_retcode);
-	if (err)
-		panic("Cannot set signal return code, err: %x.", err);
+static int __init vdso_init(void)
+{
+	unsigned int i;
+
+	vdso_pages = (vdso_end - vdso_start) >> PAGE_SHIFT;
+	vdso_pagelist =
+		kcalloc(vdso_pages + 1, sizeof(struct page *), GFP_KERNEL);
+	if (unlikely(vdso_pagelist == NULL)) {
+		pr_err("vdso: pagelist allocation failed\n");
+		return -ENOMEM;
+	}
 
-	dcache_wb_range((unsigned long)vdso, (unsigned long)vdso + 16);
+	for (i = 0; i < vdso_pages; i++) {
+		struct page *pg;
 
-	vunmap(vdso);
+		pg = virt_to_page(vdso_start + (i << PAGE_SHIFT));
+		vdso_pagelist[i] = pg;
+	}
+	vdso_pagelist[i] = virt_to_page(vdso_data);
 
 	return 0;
 }
-subsys_initcall(init_vdso);
+arch_initcall(vdso_init);
 
-int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
+int arch_setup_additional_pages(struct linux_binprm *bprm,
+	int uses_interp)
 {
-	int ret;
-	unsigned long addr;
 	struct mm_struct *mm = current->mm;
+	unsigned long vdso_base, vdso_len;
+	int ret;
 
-	mmap_write_lock(mm);
+	vdso_len = (vdso_pages + 1) << PAGE_SHIFT;
 
-	addr = get_unmapped_area(NULL, STACK_TOP, PAGE_SIZE, 0, 0);
-	if (IS_ERR_VALUE(addr)) {
-		ret = addr;
-		goto up_fail;
+	mmap_write_lock(mm);
+	vdso_base = get_unmapped_area(NULL, 0, vdso_len, 0, 0);
+	if (IS_ERR_VALUE(vdso_base)) {
+		ret = vdso_base;
+		goto end;
 	}
 
-	ret = install_special_mapping(
-			mm,
-			addr,
-			PAGE_SIZE,
-			VM_READ|VM_EXEC|VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
-			&vdso_page);
-	if (ret)
-		goto up_fail;
+	/*
+	 * Put vDSO base into mm struct. We need to do this before calling
+	 * install_special_mapping or the perf counter mmap tracking code
+	 * will fail to recognise it as a vDSO (since arch_vma_name fails).
+	 */
+	mm->context.vdso = (void *)vdso_base;
+
+	ret =
+	   install_special_mapping(mm, vdso_base, vdso_pages << PAGE_SHIFT,
+		(VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC),
+		vdso_pagelist);
+
+	if (unlikely(ret)) {
+		mm->context.vdso = NULL;
+		goto end;
+	}
 
-	mm->context.vdso = (void *)addr;
+	vdso_base += (vdso_pages << PAGE_SHIFT);
+	ret = install_special_mapping(mm, vdso_base, PAGE_SIZE,
+		(VM_READ | VM_MAYREAD), &vdso_pagelist[vdso_pages]);
 
-up_fail:
+	if (unlikely(ret))
+		mm->context.vdso = NULL;
+end:
 	mmap_write_unlock(mm);
 	return ret;
 }
 
 const char *arch_vma_name(struct vm_area_struct *vma)
 {
-	if (vma->vm_mm == NULL)
-		return NULL;
-
-	if (vma->vm_start == (long)vma->vm_mm->context.vdso)
+	if (vma->vm_mm && (vma->vm_start == (long)vma->vm_mm->context.vdso))
 		return "[vdso]";
-	else
-		return NULL;
+	if (vma->vm_mm && (vma->vm_start ==
+			   (long)vma->vm_mm->context.vdso + PAGE_SIZE))
+		return "[vdso_data]";
+	return NULL;
 }
diff --git a/arch/csky/kernel/vdso/.gitignore b/arch/csky/kernel/vdso/.gitignore
new file mode 100644
index 000000000000..3a19def868ec
--- /dev/null
+++ b/arch/csky/kernel/vdso/.gitignore
@@ -0,0 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0-only
+vdso.lds
+*.tmp
+vdso-syms.S
diff --git a/arch/csky/kernel/vdso/Makefile b/arch/csky/kernel/vdso/Makefile
new file mode 100644
index 000000000000..13ac549c6587
--- /dev/null
+++ b/arch/csky/kernel/vdso/Makefile
@@ -0,0 +1,67 @@
+# SPDX-License-Identifier: GPL-2.0-only
+
+# Absolute relocation type $(ARCH_REL_TYPE_ABS) needs to be defined before
+# the inclusion of generic Makefile.
+ARCH_REL_TYPE_ABS := R_CKCORE_ADDR32|R_CKCORE_JUMP_SLOT
+include $(srctree)/lib/vdso/Makefile
+
+# Symbols present in the vdso
+vdso-syms  = rt_sigreturn
+
+# Files to link into the vdso
+obj-vdso = $(patsubst %, %.o, $(vdso-syms)) note.o
+
+ccflags-y := -fno-stack-protector
+
+# Build rules
+targets := $(obj-vdso) vdso.so vdso.so.dbg vdso.lds vdso-dummy.o
+obj-vdso := $(addprefix $(obj)/, $(obj-vdso))
+
+obj-y += vdso.o vdso-syms.o
+CPPFLAGS_vdso.lds += -P -C -U$(ARCH)
+
+# Disable gcov profiling for VDSO code
+GCOV_PROFILE := n
+KCOV_INSTRUMENT := n
+
+# Force dependency
+$(obj)/vdso.o: $(obj)/vdso.so
+
+SYSCFLAGS_vdso.so.dbg = $(c_flags)
+$(obj)/vdso.so.dbg: $(src)/vdso.lds $(obj-vdso) FORCE
+	$(call if_changed,vdsold)
+SYSCFLAGS_vdso.so.dbg = -shared -s -Wl,-soname=linux-vdso.so.1 \
+	-Wl,--build-id=sha1 -Wl,--hash-style=both
+
+$(obj)/vdso-syms.S: $(obj)/vdso.so FORCE
+	$(call if_changed,so2s)
+
+# strip rule for the .so file
+$(obj)/%.so: OBJCOPYFLAGS := -S
+$(obj)/%.so: $(obj)/%.so.dbg FORCE
+	$(call if_changed,objcopy)
+
+# actual build commands
+# The DSO images are built using a special linker script
+# Make sure only to export the intended __vdso_xxx symbol offsets.
+quiet_cmd_vdsold = VDSOLD  $@
+      cmd_vdsold = $(CC) $(KBUILD_CFLAGS) $(call cc-option, -no-pie) -nostdlib -nostartfiles $(SYSCFLAGS_$(@F)) \
+                           -Wl,-T,$(filter-out FORCE,$^) -o $@.tmp && \
+                   $(CROSS_COMPILE)objcopy \
+                           $(patsubst %, -G __vdso_%, $(vdso-syms)) $@.tmp $@ && \
+                   rm $@.tmp
+
+# Extracts symbol offsets from the VDSO, converting them into an assembly file
+# that contains the same symbols at the same offsets.
+quiet_cmd_so2s = SO2S    $@
+      cmd_so2s = $(NM) -D $< | $(srctree)/$(src)/so2s.sh > $@
+
+# install commands for the unstripped file
+quiet_cmd_vdso_install = INSTALL $@
+      cmd_vdso_install = cp $(obj)/$@.dbg $(MODLIB)/vdso/$@
+
+vdso.so: $(obj)/vdso.so.dbg
+	@mkdir -p $(MODLIB)/vdso
+	$(call cmd,vdso_install)
+
+vdso_install: vdso.so
diff --git a/arch/csky/kernel/vdso/note.S b/arch/csky/kernel/vdso/note.S
new file mode 100644
index 000000000000..2a956c942211
--- /dev/null
+++ b/arch/csky/kernel/vdso/note.S
@@ -0,0 +1,12 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * This supplies .note.* sections to go into the PT_NOTE inside the vDSO text.
+ * Here we can supply some information useful to userland.
+ */
+
+#include <linux/elfnote.h>
+#include <linux/version.h>
+
+ELFNOTE_START(Linux, 0, "a")
+	.long LINUX_VERSION_CODE
+ELFNOTE_END
diff --git a/arch/csky/kernel/vdso/rt_sigreturn.S b/arch/csky/kernel/vdso/rt_sigreturn.S
new file mode 100644
index 000000000000..0a6bd1216118
--- /dev/null
+++ b/arch/csky/kernel/vdso/rt_sigreturn.S
@@ -0,0 +1,14 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#include <linux/linkage.h>
+#include <asm/unistd.h>
+#include <abi/vdso.h>
+
+	.text
+ENTRY(__vdso_rt_sigreturn)
+	.cfi_startproc
+	.cfi_signal_frame
+	SET_SYSCALL_ID
+	trap	0
+	.cfi_endproc
+ENDPROC(__vdso_rt_sigreturn)
diff --git a/arch/csky/kernel/vdso/so2s.sh b/arch/csky/kernel/vdso/so2s.sh
new file mode 100755
index 000000000000..69da3d529c6d
--- /dev/null
+++ b/arch/csky/kernel/vdso/so2s.sh
@@ -0,0 +1,5 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0+
+
+sed 's!\([0-9a-f]*\) T \([a-z0-9_]*\)\(@@LINUX_5.10\)*!.global \2\n.set \2,0x\1!' \
+| grep '^\.'
diff --git a/arch/csky/kernel/vdso/vdso.S b/arch/csky/kernel/vdso/vdso.S
new file mode 100644
index 000000000000..5162ca069494
--- /dev/null
+++ b/arch/csky/kernel/vdso/vdso.S
@@ -0,0 +1,16 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#include <linux/init.h>
+#include <linux/linkage.h>
+#include <asm/page.h>
+
+	__PAGE_ALIGNED_DATA
+
+	.globl vdso_start, vdso_end
+	.balign PAGE_SIZE
+vdso_start:
+	.incbin "arch/csky/kernel/vdso/vdso.so"
+	.balign PAGE_SIZE
+vdso_end:
+
+	.previous
diff --git a/arch/csky/kernel/vdso/vdso.lds.S b/arch/csky/kernel/vdso/vdso.lds.S
new file mode 100644
index 000000000000..8d226252d439
--- /dev/null
+++ b/arch/csky/kernel/vdso/vdso.lds.S
@@ -0,0 +1,54 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#include <asm/page.h>
+
+OUTPUT_ARCH(csky)
+
+SECTIONS
+{
+	PROVIDE(_vdso_data = . + PAGE_SIZE);
+	. = SIZEOF_HEADERS;
+
+	.hash		: { *(.hash) }			:text
+	.gnu.hash	: { *(.gnu.hash) }
+	.dynsym		: { *(.dynsym) }
+	.dynstr		: { *(.dynstr) }
+	.gnu.version	: { *(.gnu.version) }
+	.gnu.version_d	: { *(.gnu.version_d) }
+	.gnu.version_r	: { *(.gnu.version_r) }
+
+	.note		: { *(.note.*) }		:text	:note
+	.dynamic	: { *(.dynamic) }		:text	:dynamic
+
+	.eh_frame_hdr	: { *(.eh_frame_hdr) }		:text	:eh_frame_hdr
+	.eh_frame	: { KEEP (*(.eh_frame)) }	:text
+
+	.rodata		: { *(.rodata .rodata.* .gnu.linkonce.r.*) }
+
+	. = 0x800;
+	.text		: { *(.text .text.*) }		:text
+
+	.data		: {
+		*(.got.plt) *(.got)
+		*(.data .data.* .gnu.linkonce.d.*)
+		*(.dynbss)
+		*(.bss .bss.* .gnu.linkonce.b.*)
+	}
+}
+
+PHDRS
+{
+	text		PT_LOAD		FLAGS(5) FILEHDR PHDRS; /* PF_R|PF_X */
+	dynamic		PT_DYNAMIC	FLAGS(4);		/* PF_R */
+	note		PT_NOTE		FLAGS(4);		/* PF_R */
+	eh_frame_hdr	PT_GNU_EH_FRAME;
+}
+
+VERSION
+{
+	LINUX_5.10 {
+	global:
+		__vdso_rt_sigreturn;
+	local: *;
+	};
+}