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authorSteven Rostedt <rostedt@goodmis.org>2011-05-19 21:34:58 -0400
committerIngo Molnar <mingo@elte.hu>2011-05-20 08:56:56 +0200
commita2d063ac216c1618bfc2b4d40b7176adffa63511 (patch)
tree499d4cc67e296cb8b51f51215a49407c440c4690
parentc16dbd54a3fe126b539a0ef149d80221c667bbd5 (diff)
downloadlinux-a2d063ac216c1618bfc2b4d40b7176adffa63511.tar.gz
extable, core_kernel_data(): Make sure all archs define _sdata
A new utility function (core_kernel_data()) is used to determine if a passed in address is part of core kernel data or not. It may or may not return true for RO data, but this utility must work for RW data. Thus both _sdata and _edata must be defined and continuous, without .init sections that may later be freed and replaced by volatile memory (memory that can be freed). This utility function is used to determine if data is safe from ever being freed. Thus it should return true for all RW global data that is not in a module or has been allocated, or false otherwise. Also change core_kernel_data() back to the more precise _sdata condition and document the function. Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Acked-by: Ralf Baechle <ralf@linux-mips.org> Acked-by: Hirokazu Takata <takata@linux-m32r.org> Cc: Richard Henderson <rth@twiddle.net> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: Matt Turner <mattst88@gmail.com> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Roman Zippel <zippel@linux-m68k.org> Cc: linux-m68k@lists.linux-m68k.org Cc: Kyle McMartin <kyle@mcmartin.ca> Cc: Helge Deller <deller@gmx.de> Cc: JamesE.J.Bottomley <jejb@parisc-linux.org> Link: http://lkml.kernel.org/r/1305855298.1465.19.camel@gandalf.stny.rr.com Signed-off-by: Ingo Molnar <mingo@elte.hu> ---- arch/alpha/kernel/vmlinux.lds.S | 1 + arch/m32r/kernel/vmlinux.lds.S | 1 + arch/m68k/kernel/vmlinux-std.lds | 2 ++ arch/m68k/kernel/vmlinux-sun3.lds | 1 + arch/mips/kernel/vmlinux.lds.S | 1 + arch/parisc/kernel/vmlinux.lds.S | 3 +++ kernel/extable.c | 12 +++++++++++- 7 files changed, 20 insertions(+), 1 deletion(-)
-rw-r--r--arch/alpha/kernel/vmlinux.lds.S1
-rw-r--r--arch/m32r/kernel/vmlinux.lds.S1
-rw-r--r--arch/m68k/kernel/vmlinux-std.lds2
-rw-r--r--arch/m68k/kernel/vmlinux-sun3.lds1
-rw-r--r--arch/mips/kernel/vmlinux.lds.S1
-rw-r--r--arch/parisc/kernel/vmlinux.lds.S3
-rw-r--r--kernel/extable.c12
7 files changed, 20 insertions, 1 deletions
diff --git a/arch/alpha/kernel/vmlinux.lds.S b/arch/alpha/kernel/vmlinux.lds.S
index 433be2a24f3..3d890a98a08 100644
--- a/arch/alpha/kernel/vmlinux.lds.S
+++ b/arch/alpha/kernel/vmlinux.lds.S
@@ -46,6 +46,7 @@ SECTIONS
__init_end = .;
/* Freed after init ends here */
+ _sdata = .; /* Start of rw data section */
_data = .;
RW_DATA_SECTION(L1_CACHE_BYTES, PAGE_SIZE, THREAD_SIZE)
diff --git a/arch/m32r/kernel/vmlinux.lds.S b/arch/m32r/kernel/vmlinux.lds.S
index c194d64cdbb..cf95aec7746 100644
--- a/arch/m32r/kernel/vmlinux.lds.S
+++ b/arch/m32r/kernel/vmlinux.lds.S
@@ -44,6 +44,7 @@ SECTIONS
EXCEPTION_TABLE(16)
NOTES
+ _sdata = .; /* Start of data section */
RODATA
RW_DATA_SECTION(32, PAGE_SIZE, THREAD_SIZE)
_edata = .; /* End of data section */
diff --git a/arch/m68k/kernel/vmlinux-std.lds b/arch/m68k/kernel/vmlinux-std.lds
index 878be5f38ca..d0993594f55 100644
--- a/arch/m68k/kernel/vmlinux-std.lds
+++ b/arch/m68k/kernel/vmlinux-std.lds
@@ -25,6 +25,8 @@ SECTIONS
EXCEPTION_TABLE(16)
+ _sdata = .; /* Start of data section */
+
RODATA
RW_DATA_SECTION(16, PAGE_SIZE, THREAD_SIZE)
diff --git a/arch/m68k/kernel/vmlinux-sun3.lds b/arch/m68k/kernel/vmlinux-sun3.lds
index 1ad6b7ad2c1..8080469ee6c 100644
--- a/arch/m68k/kernel/vmlinux-sun3.lds
+++ b/arch/m68k/kernel/vmlinux-sun3.lds
@@ -25,6 +25,7 @@ SECTIONS
_etext = .; /* End of text section */
EXCEPTION_TABLE(16) :data
+ _sdata = .; /* Start of rw data section */
RW_DATA_SECTION(16, PAGE_SIZE, THREAD_SIZE) :data
/* End of data goes *here* so that freeing init code works properly. */
_edata = .;
diff --git a/arch/mips/kernel/vmlinux.lds.S b/arch/mips/kernel/vmlinux.lds.S
index cd2ca544454..01af3876cf9 100644
--- a/arch/mips/kernel/vmlinux.lds.S
+++ b/arch/mips/kernel/vmlinux.lds.S
@@ -65,6 +65,7 @@ SECTIONS
NOTES :text :note
.dummy : { *(.dummy) } :text
+ _sdata = .; /* Start of data section */
RODATA
/* writeable */
diff --git a/arch/parisc/kernel/vmlinux.lds.S b/arch/parisc/kernel/vmlinux.lds.S
index 8f1e4efd143..2d9a5c7c76f 100644
--- a/arch/parisc/kernel/vmlinux.lds.S
+++ b/arch/parisc/kernel/vmlinux.lds.S
@@ -69,6 +69,9 @@ SECTIONS
/* End of text section */
_etext = .;
+ /* Start of data section */
+ _sdata = .;
+
RODATA
/* writeable */
diff --git a/kernel/extable.c b/kernel/extable.c
index d44aac0c3fa..5339705b824 100644
--- a/kernel/extable.c
+++ b/kernel/extable.c
@@ -72,9 +72,19 @@ int core_kernel_text(unsigned long addr)
return 0;
}
+/**
+ * core_kernel_data - tell if addr points to kernel data
+ * @addr: address to test
+ *
+ * Returns true if @addr passed in is from the core kernel data
+ * section.
+ *
+ * Note: On some archs it may return true for core RODATA, and false
+ * for others. But will always be true for core RW data.
+ */
int core_kernel_data(unsigned long addr)
{
- if (addr >= (unsigned long)_stext &&
+ if (addr >= (unsigned long)_sdata &&
addr < (unsigned long)_edata)
return 1;
return 0;