[Xen-devel] [PATCH] x86: move alternative.c data fully into .init.*

["Jan Beulich" <JBeulich@xxxxxxxx>]

This wasn't done upon the initial addition of the file since the
section processing needs some adjustment for this: We can't mark the
two arrays needing relocations as either __initdata or __initconst, as
both have the potential of creating section conflicts (with -fPIC the
compiler may want to mark the section writable due to the necessary
relocations, colliding with other __initconst uses, and if the compiler
chooses to use the provided section name, __initdata on a constant
object might collide with other __initdata uses). However, local data
known to be referenced only by init code/data can also safely be moved
into .init.*. Hence the respective logic is being tweaked such that it
won't complain on non-empty .*.local sections.

While at it also drop the non-local section names from
SPECIAL_DATA_SECTIONS - they can't be safely converted.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

--- a/xen/Rules.mk
+++ b/xen/Rules.mk
@@ -167,11 +167,12 @@ _clean_%/: FORCE
        $(CC) $(AFLAGS) -c $< -o $@
 
 SPECIAL_DATA_SECTIONS := rodata $(foreach n,1 2 4 8,rodata.str1.$(n)) \
-                        $(foreach r,rel rel.ro,data.$(r) data.$(r).local)
+                        $(foreach r,rel rel.ro,data.$(r).local)
 
 $(filter %.init.o,$(obj-y) $(obj-bin-y) $(extra-y)): %.init.o: %.o Makefile
        $(OBJDUMP) -h $< | sed -n '/[0-9]/{s,00*,0,g;p;}' | while read idx name 
sz rest; do \
                case "$$name" in \
+               .*.local) ;; \
                .text|.text.*|.data|.data.*|.bss) \
                        test $$sz != 0 || continue; \
                        echo "Error: size of $<:$$name is 0x$$sz" >&2; \
--- a/xen/arch/x86/Makefile
+++ b/xen/arch/x86/Makefile
@@ -7,7 +7,7 @@ subdir-y += oprofile
 
 subdir-$(x86_64) += x86_64
 
-obj-y += alternative.o
+obj-bin-y += alternative.init.o
 obj-y += apic.o
 obj-y += bitops.o
 obj-bin-y += bzimage.init.o
--- a/xen/arch/x86/alternative.c
+++ b/xen/arch/x86/alternative.c
@@ -39,7 +39,7 @@ static const unsigned char k8nops[] __in
     K8_NOP7,
     K8_NOP8
 };
-static const unsigned char * const k8_nops[ASM_NOP_MAX+1] /*__initconst*/ = {
+static const unsigned char * const k8_nops[ASM_NOP_MAX+1] = {
     NULL,
     k8nops,
     k8nops + 1,
@@ -63,7 +63,7 @@ static const unsigned char p6nops[] __in
     P6_NOP7,
     P6_NOP8
 };
-static const unsigned char * const p6_nops[ASM_NOP_MAX+1] /*__initconst*/ = {
+static const unsigned char * const p6_nops[ASM_NOP_MAX+1] = {
     NULL,
     p6nops,
     p6nops + 1,

Attachment: x86-alternative-placement.patch
Description: Text document

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