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authorDavid Daney <ddaney@caviumnetworks.com>2010-02-18 16:13:04 -0800
committerRalf Baechle <ralf@linux-mips.org>2010-04-12 17:26:14 +0100
commitc52d0d30aef84aa8893b34e5254716c8ab5c4472 (patch)
tree0ba93eb7e305229ceb2ee04119dc7ab22b9fa33d /arch/mips/kernel
parent58b9e2239fa63c7c470acb4a77e9da17e6a6fa4f (diff)
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MIPS: Preliminary VDSO
This is a preliminary patch to add a vdso to all user processes. Still missing are ELF headers and .eh_frame information. But it is enough to allow us to move signal trampolines off of the stack. Note that emulation of branch delay slots in the FPU emulator still requires the stack. We allocate a single page (the vdso) and write all possible signal trampolines into it. The stack is moved down by one page and the vdso is mapped into this space. Signed-off-by: David Daney <ddaney@caviumnetworks.com> To: linux-mips@linux-mips.org Patchwork: http://patchwork.linux-mips.org/patch/975/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Diffstat (limited to 'arch/mips/kernel')
-rw-r--r--arch/mips/kernel/Makefile2
-rw-r--r--arch/mips/kernel/syscall.c6
-rw-r--r--arch/mips/kernel/vdso.c112
3 files changed, 118 insertions, 2 deletions
diff --git a/arch/mips/kernel/Makefile b/arch/mips/kernel/Makefile
index ef20957ca14..7a6ac501cbb 100644
--- a/arch/mips/kernel/Makefile
+++ b/arch/mips/kernel/Makefile
@@ -6,7 +6,7 @@ extra-y := head.o init_task.o vmlinux.lds
obj-y += cpu-probe.o branch.o entry.o genex.o irq.o process.o \
ptrace.o reset.o setup.o signal.o syscall.o \
- time.o topology.o traps.o unaligned.o watch.o
+ time.o topology.o traps.o unaligned.o watch.o vdso.o
ifdef CONFIG_FUNCTION_TRACER
CFLAGS_REMOVE_ftrace.o = -pg
diff --git a/arch/mips/kernel/syscall.c b/arch/mips/kernel/syscall.c
index 9587abc67f3..dd81b0f8751 100644
--- a/arch/mips/kernel/syscall.c
+++ b/arch/mips/kernel/syscall.c
@@ -79,7 +79,11 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
int do_color_align;
unsigned long task_size;
- task_size = STACK_TOP;
+#ifdef CONFIG_32BIT
+ task_size = TASK_SIZE;
+#else /* Must be CONFIG_64BIT*/
+ task_size = test_thread_flag(TIF_32BIT_ADDR) ? TASK_SIZE32 : TASK_SIZE;
+#endif
if (len > task_size)
return -ENOMEM;
diff --git a/arch/mips/kernel/vdso.c b/arch/mips/kernel/vdso.c
new file mode 100644
index 00000000000..b773c1112b1
--- /dev/null
+++ b/arch/mips/kernel/vdso.c
@@ -0,0 +1,112 @@
+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 2009, 2010 Cavium Networks, Inc.
+ */
+
+
+#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 <asm/vdso.h>
+#include <asm/uasm.h>
+
+/*
+ * Including <asm/unistd.h> would give use the 64-bit syscall numbers ...
+ */
+#define __NR_O32_sigreturn 4119
+#define __NR_O32_rt_sigreturn 4193
+#define __NR_N32_rt_sigreturn 6211
+
+static struct page *vdso_page;
+
+static void __init install_trampoline(u32 *tramp, unsigned int sigreturn)
+{
+ uasm_i_addiu(&tramp, 2, 0, sigreturn); /* li v0, sigreturn */
+ uasm_i_syscall(&tramp, 0);
+}
+
+static int __init init_vdso(void)
+{
+ struct mips_vdso *vdso;
+
+ vdso_page = alloc_page(GFP_KERNEL);
+ if (!vdso_page)
+ panic("Cannot allocate vdso");
+
+ vdso = vmap(&vdso_page, 1, 0, PAGE_KERNEL);
+ if (!vdso)
+ panic("Cannot map vdso");
+ clear_page(vdso);
+
+ install_trampoline(vdso->rt_signal_trampoline, __NR_rt_sigreturn);
+#ifdef CONFIG_32BIT
+ install_trampoline(vdso->signal_trampoline, __NR_sigreturn);
+#else
+ install_trampoline(vdso->n32_rt_signal_trampoline,
+ __NR_N32_rt_sigreturn);
+ install_trampoline(vdso->o32_signal_trampoline, __NR_O32_sigreturn);
+ install_trampoline(vdso->o32_rt_signal_trampoline,
+ __NR_O32_rt_sigreturn);
+#endif
+
+ vunmap(vdso);
+
+ pr_notice("init_vdso successfull\n");
+
+ return 0;
+}
+device_initcall(init_vdso);
+
+static unsigned long vdso_addr(unsigned long start)
+{
+ return STACK_TOP;
+}
+
+int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
+{
+ int ret;
+ unsigned long addr;
+ struct mm_struct *mm = current->mm;
+
+ down_write(&mm->mmap_sem);
+
+ addr = vdso_addr(mm->start_stack);
+
+ addr = get_unmapped_area(NULL, addr, PAGE_SIZE, 0, 0);
+ if (IS_ERR_VALUE(addr)) {
+ ret = addr;
+ goto up_fail;
+ }
+
+ ret = install_special_mapping(mm, addr, PAGE_SIZE,
+ VM_READ|VM_EXEC|
+ VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC|
+ VM_ALWAYSDUMP,
+ &vdso_page);
+
+ if (ret)
+ goto up_fail;
+
+ mm->context.vdso = (void *)addr;
+
+up_fail:
+ up_write(&mm->mmap_sem);
+ return ret;
+}
+
+const char *arch_vma_name(struct vm_area_struct *vma)
+{
+ if (vma->vm_mm && vma->vm_start == (long)vma->vm_mm->context.vdso)
+ return "[vdso]";
+ return NULL;
+}