powerpc/vdso: Use builtin symbols to locate fixup section

Add builtin symbols to locate fixup section and use them
instead of locating sections through elf headers at runtime.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/2954526981859ca1ccfcfc7a7c4263920e9ddfcb.1601197618.git.christophe.leroy@csgroup.eu

3 files changed, 30 insertions, 41 deletions

diff --git a/arch/powerpc/kernel/vdso.c b/arch/powerpc/kernel/vdso.c
index e10bc0d9856c..27449202c1d7 100644
--- a/arch/powerpc/kernel/vdso.c
+++ b/arch/powerpc/kernel/vdso.c
@@ -434,6 +434,12 @@ static int __init vdso_do_func_patch64(struct lib32_elfinfo *v32,
 
 #endif /* CONFIG_PPC64 */
 
+#define VDSO_DO_FIXUPS(type, value, bits, sec) do {					\
+	void *__start = (void *)VDSO##bits##_SYMBOL(&vdso##bits##_start, sec##_start);	\
+	void *__end = (void *)VDSO##bits##_SYMBOL(&vdso##bits##_start, sec##_end);	\
+											\
+	do_##type##_fixups((value), __start, __end);					\
+} while (0)
 
 static __init int vdso_do_find_sections(struct lib32_elfinfo *v32,
 					struct lib64_elfinfo *v64)
@@ -530,53 +536,20 @@ static __init int vdso_fixup_datapage(struct lib32_elfinfo *v32,
 static __init int vdso_fixup_features(struct lib32_elfinfo *v32,
 				      struct lib64_elfinfo *v64)
 {
-	unsigned long size;
-	void *start;
-
 #ifdef CONFIG_PPC64
-	start = find_section64(v64->hdr, "__ftr_fixup", &size);
-	if (start)
-		do_feature_fixups(cur_cpu_spec->cpu_features,
-				  start, start + size);
-
-	start = find_section64(v64->hdr, "__mmu_ftr_fixup", &size);
-	if (start)
-		do_feature_fixups(cur_cpu_spec->mmu_features,
-				  start, start + size);
-
-	start = find_section64(v64->hdr, "__fw_ftr_fixup", &size);
-	if (start)
-		do_feature_fixups(powerpc_firmware_features,
-				  start, start + size);
-
-	start = find_section64(v64->hdr, "__lwsync_fixup", &size);
-	if (start)
-		do_lwsync_fixups(cur_cpu_spec->cpu_features,
-				 start, start + size);
+	VDSO_DO_FIXUPS(feature, cur_cpu_spec->cpu_features, 64, ftr_fixup);
+	VDSO_DO_FIXUPS(feature, cur_cpu_spec->mmu_features, 64, mmu_ftr_fixup);
+	VDSO_DO_FIXUPS(feature, powerpc_firmware_features, 64, fw_ftr_fixup);
+	VDSO_DO_FIXUPS(lwsync, cur_cpu_spec->cpu_features, 64, lwsync_fixup);
 #endif /* CONFIG_PPC64 */
 
 #ifdef CONFIG_VDSO32
-	start = find_section32(v32->hdr, "__ftr_fixup", &size);
-	if (start)
-		do_feature_fixups(cur_cpu_spec->cpu_features,
-				  start, start + size);
-
-	start = find_section32(v32->hdr, "__mmu_ftr_fixup", &size);
-	if (start)
-		do_feature_fixups(cur_cpu_spec->mmu_features,
-				  start, start + size);
-
+	VDSO_DO_FIXUPS(feature, cur_cpu_spec->cpu_features, 32, ftr_fixup);
+	VDSO_DO_FIXUPS(feature, cur_cpu_spec->mmu_features, 32, mmu_ftr_fixup);
 #ifdef CONFIG_PPC64
-	start = find_section32(v32->hdr, "__fw_ftr_fixup", &size);
-	if (start)
-		do_feature_fixups(powerpc_firmware_features,
-				  start, start + size);
+	VDSO_DO_FIXUPS(feature, powerpc_firmware_features, 32, fw_ftr_fixup);
 #endif /* CONFIG_PPC64 */
-
-	start = find_section32(v32->hdr, "__lwsync_fixup", &size);
-	if (start)
-		do_lwsync_fixups(cur_cpu_spec->cpu_features,
-				 start, start + size);
+	VDSO_DO_FIXUPS(lwsync, cur_cpu_spec->cpu_features, 32, lwsync_fixup);
 #endif
 
 	return 0;
diff --git a/arch/powerpc/kernel/vdso32/vdso32.lds.S b/arch/powerpc/kernel/vdso32/vdso32.lds.S
index 078d75c0cd24..dc62772f028c 100644
--- a/arch/powerpc/kernel/vdso32/vdso32.lds.S
+++ b/arch/powerpc/kernel/vdso32/vdso32.lds.S
@@ -38,17 +38,25 @@ SECTIONS
 	PROVIDE(etext = .);
 
 	. = ALIGN(8);
+	VDSO_ftr_fixup_start = .;
 	__ftr_fixup	: { *(__ftr_fixup) }
+	VDSO_ftr_fixup_end = .;
 
 	. = ALIGN(8);
+	VDSO_mmu_ftr_fixup_start = .;
 	__mmu_ftr_fixup	: { *(__mmu_ftr_fixup) }
+	VDSO_mmu_ftr_fixup_end = .;
 
 	. = ALIGN(8);
+	VDSO_lwsync_fixup_start = .;
 	__lwsync_fixup	: { *(__lwsync_fixup) }
+	VDSO_lwsync_fixup_end = .;
 
 #ifdef CONFIG_PPC64
 	. = ALIGN(8);
+	VDSO_fw_ftr_fixup_start = .;
 	__fw_ftr_fixup	: { *(__fw_ftr_fixup) }
+	VDSO_fw_ftr_fixup_end = .;
 #endif
 
 	/*
diff --git a/arch/powerpc/kernel/vdso64/vdso64.lds.S b/arch/powerpc/kernel/vdso64/vdso64.lds.S
index 1f06e4f730a8..913d34e8bd05 100644
--- a/arch/powerpc/kernel/vdso64/vdso64.lds.S
+++ b/arch/powerpc/kernel/vdso64/vdso64.lds.S
@@ -39,16 +39,24 @@ SECTIONS
 	PROVIDE(etext = .);
 
 	. = ALIGN(8);
+	VDSO_ftr_fixup_start = .;
 	__ftr_fixup	: { *(__ftr_fixup) }
+	VDSO_ftr_fixup_end = .;
 
 	. = ALIGN(8);
+	VDSO_mmu_ftr_fixup_start = .;
 	__mmu_ftr_fixup	: { *(__mmu_ftr_fixup) }
+	VDSO_mmu_ftr_fixup_end = .;
 
 	. = ALIGN(8);
+	VDSO_lwsync_fixup_start = .;
 	__lwsync_fixup	: { *(__lwsync_fixup) }
+	VDSO_lwsync_fixup_end = .;
 
 	. = ALIGN(8);
+	VDSO_fw_ftr_fixup_start = .;
 	__fw_ftr_fixup	: { *(__fw_ftr_fixup) }
+	VDSO_fw_ftr_fixup_end = .;
 
 	/*
 	 * Other stuff is appended to the text segment: