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Subject[PATCH 4.14 19/75] selftests/x86/ldt_get: Add a few additional tests for limits
Date
4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Andy Lutomirski <luto@kernel.org>


[ Upstream commit fec8f5ae1715a01c72ad52cb2ecd8aacaf142302 ]

We weren't testing the .limit and .limit_in_pages fields very well.
Add more tests.

This addition seems to trigger the "bits 16:19 are undefined" issue
that was fixed in an earlier patch. I think that, at least on my
CPU, the high nibble of the limit ends in LAR bits 16:19.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bpetkov@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/5601c15ea9b3113d288953fd2838b18bedf6bc67.1509794321.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
tools/testing/selftests/x86/ldt_gdt.c | 17 ++++++++++++++++-
1 file changed, 16 insertions(+), 1 deletion(-)

--- a/tools/testing/selftests/x86/ldt_gdt.c
+++ b/tools/testing/selftests/x86/ldt_gdt.c
@@ -367,9 +367,24 @@ static void do_simple_tests(void)
install_invalid(&desc, false);

desc.seg_not_present = 0;
- desc.read_exec_only = 0;
desc.seg_32bit = 1;
+ desc.read_exec_only = 0;
+ desc.limit = 0xfffff;
+
install_valid(&desc, AR_DPL3 | AR_TYPE_RWDATA | AR_S | AR_P | AR_DB);
+
+ desc.limit_in_pages = 1;
+
+ install_valid(&desc, AR_DPL3 | AR_TYPE_RWDATA | AR_S | AR_P | AR_DB | AR_G);
+ desc.read_exec_only = 1;
+ install_valid(&desc, AR_DPL3 | AR_TYPE_RODATA | AR_S | AR_P | AR_DB | AR_G);
+ desc.contents = 1;
+ desc.read_exec_only = 0;
+ install_valid(&desc, AR_DPL3 | AR_TYPE_RWDATA_EXPDOWN | AR_S | AR_P | AR_DB | AR_G);
+ desc.read_exec_only = 1;
+ install_valid(&desc, AR_DPL3 | AR_TYPE_RODATA_EXPDOWN | AR_S | AR_P | AR_DB | AR_G);
+
+ desc.limit = 0;
install_invalid(&desc, true);
}


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