powerpc/lib: Add alt patching test of branching past the last instruction

Add a test of the relative branch patching logic in the alternate
section feature fixup code. This tests that if we branch past the last
instruction of the alternate section, the branch is not patched.
That's because the assembler will have created a branch that already
points to the first instruction after the patched section, which is
correct and needs no further patching.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

diff --git a/arch/powerpc/lib/feature-fixups-test.S b/arch/powerpc/lib/feature-fixups-test.S
index dd05afcbcde35ce7da86793b56b342cd720e3e62..f16cec98950602afc4e4de88dbf6582133ec0694 100644 (file)
--- a/arch/powerpc/lib/feature-fixups-test.S
+++ b/arch/powerpc/lib/feature-fixups-test.S
@@ -171,6 +171,42 @@ globl(ftr_fixup_test6_expected)
        or      2,2,2
        or      3,3,3
 
+globl(ftr_fixup_test7)
+       or      1,1,1
+BEGIN_FTR_SECTION
+       or      2,2,2
+       or      2,2,2
+       or      2,2,2
+       or      2,2,2
+       or      2,2,2
+       or      2,2,2
+       or      2,2,2
+FTR_SECTION_ELSE
+2:     b       3f
+3:     or      5,5,5
+       beq     3b
+       b       1f
+       or      6,6,6
+       b       2b
+       bdnz    3b
+1:
+ALT_FTR_SECTION_END(0, 1)
+       or      1,1,1
+       or      1,1,1
+
+globl(end_ftr_fixup_test7)
+       nop
+
+globl(ftr_fixup_test7_expected)
+       or      1,1,1
+2:     b       3f
+3:     or      5,5,5
+       beq     3b
+       b       1f
+       or      6,6,6
+       b       2b
+       bdnz    3b
+1:     or      1,1,1
 
 #if 0
 /* Test that if we have a larger else case the assembler spots it and

diff --git a/arch/powerpc/lib/feature-fixups.c b/arch/powerpc/lib/feature-fixups.c
index 097b45bd9de4f40218fa09a25a2b5d1d0df1bcd9..f3e46d4edd72d48d424c69f9b00de0d9d26eb380 100644 (file)
--- a/arch/powerpc/lib/feature-fixups.c
+++ b/arch/powerpc/lib/feature-fixups.c
@@ -425,6 +425,16 @@ static void test_alternative_case_with_external_branch(void)
        check(memcmp(ftr_fixup_test6, ftr_fixup_test6_expected, size) == 0);
 }
 
+static void test_alternative_case_with_branch_to_end(void)
+{
+       extern unsigned int ftr_fixup_test7[];
+       extern unsigned int end_ftr_fixup_test7[];
+       extern unsigned int ftr_fixup_test7_expected[];
+       int size = 4 * (end_ftr_fixup_test7 - ftr_fixup_test7);
+
+       check(memcmp(ftr_fixup_test7, ftr_fixup_test7_expected, size) == 0);
+}
+
 static void test_cpu_macros(void)
 {
        extern u8 ftr_fixup_test_FTR_macros[];
@@ -480,6 +490,7 @@ static int __init test_feature_fixups(void)
        test_alternative_case_too_small();
        test_alternative_case_with_branch();
        test_alternative_case_with_external_branch();
+       test_alternative_case_with_branch_to_end();
        test_cpu_macros();
        test_fw_macros();
        test_lwsync_macros();