[3/5] powerpc/lib: Fix the feature fixup tests to actually work

Message ID 20180416143905.2716-3-mpe@ellerman.id.au
State New
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Series
  • [1/5] powerpc/lib: Fix off-by-one in alternate feature patching
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Commit Message

Michael Ellerman April 16, 2018, 2:39 p.m.
The code patching code has always been a bit confused about whether
it's best to use void *, unsigned int *, char *, etc. to point to
instructions. In fact in the feature fixups tests we use both unsigned
int[] and u8[] in different places.

Unfortunately the tests that use unsigned int[] calculate the size of
the code blocks using subtraction of those unsigned int pointers, and
then pass the result to memcmp(). This means we're only comparing 1/4
of the bytes we need to, because we need to multiply by
sizeof(unsigned int) to get the number of *bytes*.

The result is that the tests do all the patching and then only compare
some of the resulting code, so patching bugs that only effect that
last 3/4 of the code could slip through undetected. It turns out that
hasn't been happening, although one test had a bad expected case (see
previous commit).

Fix it for now by multiplying the size by 4 in the affected functions.

Fixes: 362e7701fd18 ("powerpc: Add self-tests of the feature fixup code")
Epic-brown-paper-bag-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
---
 arch/powerpc/lib/feature-fixups.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

Patch

diff --git a/arch/powerpc/lib/feature-fixups.c b/arch/powerpc/lib/feature-fixups.c
index 288fe4f0db4e..097b45bd9de4 100644
--- a/arch/powerpc/lib/feature-fixups.c
+++ b/arch/powerpc/lib/feature-fixups.c
@@ -285,7 +285,7 @@  static void test_basic_patching(void)
 	extern unsigned int end_ftr_fixup_test1[];
 	extern unsigned int ftr_fixup_test1_orig[];
 	extern unsigned int ftr_fixup_test1_expected[];
-	int size = end_ftr_fixup_test1 - ftr_fixup_test1;
+	int size = 4 * (end_ftr_fixup_test1 - ftr_fixup_test1);
 
 	fixup.value = fixup.mask = 8;
 	fixup.start_off = calc_offset(&fixup, ftr_fixup_test1 + 1);
@@ -317,7 +317,7 @@  static void test_alternative_patching(void)
 	extern unsigned int ftr_fixup_test2_orig[];
 	extern unsigned int ftr_fixup_test2_alt[];
 	extern unsigned int ftr_fixup_test2_expected[];
-	int size = end_ftr_fixup_test2 - ftr_fixup_test2;
+	int size = 4 * (end_ftr_fixup_test2 - ftr_fixup_test2);
 
 	fixup.value = fixup.mask = 0xF;
 	fixup.start_off = calc_offset(&fixup, ftr_fixup_test2 + 1);
@@ -349,7 +349,7 @@  static void test_alternative_case_too_big(void)
 	extern unsigned int end_ftr_fixup_test3[];
 	extern unsigned int ftr_fixup_test3_orig[];
 	extern unsigned int ftr_fixup_test3_alt[];
-	int size = end_ftr_fixup_test3 - ftr_fixup_test3;
+	int size = 4 * (end_ftr_fixup_test3 - ftr_fixup_test3);
 
 	fixup.value = fixup.mask = 0xC;
 	fixup.start_off = calc_offset(&fixup, ftr_fixup_test3 + 1);
@@ -376,7 +376,7 @@  static void test_alternative_case_too_small(void)
 	extern unsigned int ftr_fixup_test4_orig[];
 	extern unsigned int ftr_fixup_test4_alt[];
 	extern unsigned int ftr_fixup_test4_expected[];
-	int size = end_ftr_fixup_test4 - ftr_fixup_test4;
+	int size = 4 * (end_ftr_fixup_test4 - ftr_fixup_test4);
 	unsigned long flag;
 
 	/* Check a high-bit flag */
@@ -410,7 +410,7 @@  static void test_alternative_case_with_branch(void)
 	extern unsigned int ftr_fixup_test5[];
 	extern unsigned int end_ftr_fixup_test5[];
 	extern unsigned int ftr_fixup_test5_expected[];
-	int size = end_ftr_fixup_test5 - ftr_fixup_test5;
+	int size = 4 * (end_ftr_fixup_test5 - ftr_fixup_test5);
 
 	check(memcmp(ftr_fixup_test5, ftr_fixup_test5_expected, size) == 0);
 }
@@ -420,7 +420,7 @@  static void test_alternative_case_with_external_branch(void)
 	extern unsigned int ftr_fixup_test6[];
 	extern unsigned int end_ftr_fixup_test6[];
 	extern unsigned int ftr_fixup_test6_expected[];
-	int size = end_ftr_fixup_test6 - ftr_fixup_test6;
+	int size = 4 * (end_ftr_fixup_test6 - ftr_fixup_test6);
 
 	check(memcmp(ftr_fixup_test6, ftr_fixup_test6_expected, size) == 0);
 }