| From | lizf@kernel ... | Subject | [PATCH 3.4 080/176] x86, um: actually mark system call tables readonly | Date | Thu, 9 Apr 2015 16:45:28 +0800 |
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From: Daniel Borkmann <dborkman@redhat.com>
3.4.107-rc1 review patch. If anyone has any objections, please let me know.
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commit b485342bd79af363c77ef1a421c4a0aef2de9812 upstream.
Commit a074335a370e ("x86, um: Mark system call tables readonly") was supposed to mark the sys_call_table in UML as RO by adding the const, but it doesn't have the desired effect as it's nevertheless being placed into the data section since __cacheline_aligned enforces sys_call_table being placed into .data..cacheline_aligned instead. We need to use the ____cacheline_aligned version instead to fix this issue.
Before:
$ nm -v arch/x86/um/sys_call_table_64.o | grep -1 "sys_call_table" U sys_writev 0000000000000000 D sys_call_table 0000000000000000 D syscall_table_size
After:
$ nm -v arch/x86/um/sys_call_table_64.o | grep -1 "sys_call_table" U sys_writev 0000000000000000 R sys_call_table 0000000000000000 D syscall_table_size
Fixes: a074335a370e ("x86, um: Mark system call tables readonly") Cc: H. Peter Anvin <hpa@zytor.com> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Daniel Borkmann <dborkman@redhat.com> Signed-off-by: Richard Weinberger <richard@nod.at> Signed-off-by: Zefan Li <lizefan@huawei.com> --- arch/x86/um/sys_call_table_32.c | 2 +- arch/x86/um/sys_call_table_64.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/x86/um/sys_call_table_32.c b/arch/x86/um/sys_call_table_32.c index 68d1dc9..bd8b159 100644 --- a/arch/x86/um/sys_call_table_32.c +++ b/arch/x86/um/sys_call_table_32.c @@ -43,7 +43,7 @@ typedef asmlinkage void (*sys_call_ptr_t)(void); extern asmlinkage void sys_ni_syscall(void); -const sys_call_ptr_t sys_call_table[] __cacheline_aligned = { +const sys_call_ptr_t sys_call_table[] ____cacheline_aligned = { /* * Smells like a compiler bug -- it doesn't work * when the & below is removed. diff --git a/arch/x86/um/sys_call_table_64.c b/arch/x86/um/sys_call_table_64.c index 9924776..cbdab94 100644 --- a/arch/x86/um/sys_call_table_64.c +++ b/arch/x86/um/sys_call_table_64.c @@ -48,7 +48,7 @@ typedef void (*sys_call_ptr_t)(void); extern void sys_ni_syscall(void); -const sys_call_ptr_t sys_call_table[] __cacheline_aligned = { +const sys_call_ptr_t sys_call_table[] ____cacheline_aligned = { /* * Smells like a compiler bug -- it doesn't work * when the & below is removed. -- 1.9.1
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