diff mbox series

[RFC,08/13] x86/um/vdso: nommu: vdso memory update

Message ID 18e83579370620b2b35d35b4ca1b7609d20fb8d3.1729770373.git.thehajime@gmail.com
State RFC
Headers show
Series [RFC,01/13] fs: binfmt_elf_efpic: add architecture hook elf_arch_finalize_exec | expand

Commit Message

Hajime Tazaki Oct. 24, 2024, 12:09 p.m. UTC 
On !MMU mode, the address of vdso is accessible from userspace.  This
commit implements the entry point by pointing a block of page address.

This commit also add memory permission configuration of vdso page to be
executable.

Signed-off-by: Hajime Tazaki <thehajime@gmail.com>
Signed-off-by: Ricardo Koller <ricarkol@google.com>
---
 arch/x86/um/vdso/um_vdso.c | 20 ++++++++++++++++++++
 arch/x86/um/vdso/vma.c     | 16 +++++++++++++++-
 2 files changed, 35 insertions(+), 1 deletion(-)

Comments

Johannes Berg Oct. 25, 2024, 9:29 a.m. UTC | #1 
>  oom:
> -	printk(KERN_ERR "Cannot allocate vdso\n");
> +	pr_err("Cannot allocate vdso");

kind of unrelated change

johannes
Hajime Tazaki Oct. 25, 2024, 1:28 p.m. UTC | #2 
On Fri, 25 Oct 2024 18:29:07 +0900,
Johannes Berg wrote:
> 
> 
> >  oom:
> > -	printk(KERN_ERR "Cannot allocate vdso\n");
> > +	pr_err("Cannot allocate vdso");
> 
> kind of unrelated change

thanks, will fix it.

-- Hajime
diff mbox series

Patch

diff --git a/arch/x86/um/vdso/um_vdso.c b/arch/x86/um/vdso/um_vdso.c
index cbae2584124f..eff3e6641a0e 100644
--- a/arch/x86/um/vdso/um_vdso.c
+++ b/arch/x86/um/vdso/um_vdso.c
@@ -23,10 +23,17 @@  int __vdso_clock_gettime(clockid_t clock, struct __kernel_old_timespec *ts)
 {
 	long ret;
 
+#ifdef CONFIG_MMU
 	asm("syscall"
 		: "=a" (ret)
 		: "0" (__NR_clock_gettime), "D" (clock), "S" (ts)
 		: "rcx", "r11", "memory");
+#else
+	asm("call *%1"
+		: "=a" (ret)
+		: "0" ((unsigned long)__NR_clock_gettime), "D" (clock), "S" (ts)
+		: "rcx", "r11", "memory");
+#endif
 
 	return ret;
 }
@@ -37,10 +44,17 @@  int __vdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz)
 {
 	long ret;
 
+#ifdef CONFIG_MMU
 	asm("syscall"
 		: "=a" (ret)
 		: "0" (__NR_gettimeofday), "D" (tv), "S" (tz)
 		: "rcx", "r11", "memory");
+#else
+	asm("call *%1"
+		: "=a" (ret)
+		: "0" ((unsigned long)__NR_gettimeofday), "D" (tv), "S" (tz)
+		: "rcx", "r11", "memory");
+#endif
 
 	return ret;
 }
@@ -51,9 +65,15 @@  __kernel_old_time_t __vdso_time(__kernel_old_time_t *t)
 {
 	long secs;
 
+#ifdef CONFIG_MMU
 	asm volatile("syscall"
 		: "=a" (secs)
 		: "0" (__NR_time), "D" (t) : "cc", "r11", "cx", "memory");
+#else
+	asm("call *%1"
+		: "=a" (secs)
+		: "0" ((unsigned long)__NR_time), "D" (t) : "cc", "r11", "cx", "memory");
+#endif
 
 	return secs;
 }
diff --git a/arch/x86/um/vdso/vma.c b/arch/x86/um/vdso/vma.c
index f238f7b33cdd..36ac644147b6 100644
--- a/arch/x86/um/vdso/vma.c
+++ b/arch/x86/um/vdso/vma.c
@@ -9,6 +9,7 @@ 
 #include <asm/page.h>
 #include <asm/elf.h>
 #include <linux/init.h>
+#include <os.h>
 
 static unsigned int __read_mostly vdso_enabled = 1;
 unsigned long um_vdso_addr;
@@ -24,7 +25,9 @@  static int __init init_vdso(void)
 
 	BUG_ON(vdso_end - vdso_start > PAGE_SIZE);
 
+#ifdef CONFIG_MMU
 	um_vdso_addr = task_size - PAGE_SIZE;
+#endif
 
 	vdsop = kmalloc(sizeof(struct page *), GFP_KERNEL);
 	if (!vdsop)
@@ -40,16 +43,26 @@  static int __init init_vdso(void)
 	copy_page(page_address(um_vdso), vdso_start);
 	*vdsop = um_vdso;
 
+#ifndef CONFIG_MMU
+	/* this is fine with NOMMU as everything is accessible */
+	um_vdso_addr = (unsigned long)page_address(um_vdso);
+	os_protect_memory((void *)um_vdso_addr, vdso_end - vdso_start, 1, 1, 1);
+	pr_debug("vdso_start=%lx um_vdso_addr=%lx pg_um_vdso=%lx",
+	       (unsigned long)vdso_start, um_vdso_addr,
+	       (unsigned long)page_address(um_vdso));
+#endif
+
 	return 0;
 
 oom:
-	printk(KERN_ERR "Cannot allocate vdso\n");
+	pr_err("Cannot allocate vdso");
 	vdso_enabled = 0;
 
 	return -ENOMEM;
 }
 subsys_initcall(init_vdso);
 
+#ifdef CONFIG_MMU
 int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
 {
 	struct vm_area_struct *vma;
@@ -74,3 +87,4 @@  int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
 
 	return IS_ERR(vma) ? PTR_ERR(vma) : 0;
 }
+#endif