[PATCH 3.16 042/366] powerpc/lib: Fix the feature fixup tests to actually work

Ben Hutchings
2018-11-12T06:05:46Z

From: Michael Ellerman <mpe@ellerman.id.au>

commit cad0e39023b43d94d5e38dfd55c103e15bdd093d upstream.

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>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
arch/powerpc/lib/feature-fixups.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)

--- a/arch/powerpc/lib/feature-fixups.c
+++ b/arch/powerpc/lib/feature-fixups.c
@@ -170,7 +170,7 @@ 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);
@@ -202,7 +202,7 @@ static void test_alternative_patching(vo
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);
@@ -234,7 +234,7 @@ static void test_alternative_case_too_bi
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);
@@ -261,7 +261,7 @@ static void test_alternative_case_too_sm
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 */
@@ -295,7 +295,7 @@ static void test_alternative_case_with_b
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);
}
@@ -305,7 +305,7 @@ static void test_alternative_case_with_e
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);
}