Leverage the new infrastructure in xen/linkage.h to also switch to per-
function sections (when configured), deriving the specific name from the
"base" section in use at the time FUNC() is invoked.
Signed-off-by: Jan Beulich <jbeul...@suse.com>
---
RFC: Since we use .subsection in UNLIKELY_START(), a perhaps not really
wanted side effect of this change is that respective out-of-line
code now moves much closer to its original (invoking) code.
Note that we'd need to split DATA() in order to separate r/w and r/o
contributions. Further splitting might be needed to also support more
advanced attributes (e.g. merge), hence why this isn't done right here.
Sadly while a new section's name can be derived from the presently in
use, its attributes cannot be. Hence perhaps the only thing we can do is
give DATA() a 2nd mandatory parameter. Then again I guess most data
definitions could be moved to C anyway.
--- a/xen/Makefile
+++ b/xen/Makefile
@@ -399,6 +399,9 @@ AFLAGS += -D__ASSEMBLY__
$(call cc-option-add,AFLAGS,CC,-Wa$(comma)--noexecstack)
+# Check to see whether the assmbler supports the --sectname-subst option.
+$(call cc-option-add,AFLAGS,CC,-Wa$$(comma)--sectname-subst
-DHAVE_AS_SECTNAME_SUBST)
+
LDFLAGS-$(call ld-option,--warn-rwx-segments) += --no-warn-rwx-segments
CFLAGS += $(CFLAGS-y)
--- a/xen/arch/arm/xen.lds.S
+++ b/xen/arch/arm/xen.lds.S
@@ -154,6 +154,9 @@ SECTIONS
.init.text : {
_sinittext = .;
*(.init.text)
+#ifdef CONFIG_CC_SPLIT_SECTIONS
+ *(.init.text.*)
+#endif
_einittext = .;
. = ALIGN(PAGE_SIZE); /* Avoid mapping alt insns executable */
*(.altinstr_replacement)
--- a/xen/arch/ppc/xen.lds.S
+++ b/xen/arch/ppc/xen.lds.S
@@ -106,6 +106,9 @@ SECTIONS
DECL_SECTION(.init.text) {
_sinittext = .;
*(.init.text)
+#ifdef CONFIG_CC_SPLIT_SECTIONS
+ *(.init.text.*)
+#endif
_einittext = .;
. = ALIGN(PAGE_SIZE); /* Avoid mapping alt insns executable */
} :text
--- a/xen/arch/riscv/xen.lds.S
+++ b/xen/arch/riscv/xen.lds.S
@@ -92,6 +92,9 @@ SECTIONS
.init.text : {
_sinittext = .;
*(.init.text)
+#ifdef CONFIG_CC_SPLIT_SECTIONS
+ *(.init.text.*)
+#endif
_einittext = .;
. = ALIGN(PAGE_SIZE); /* Avoid mapping alt insns executable */
} :text
--- a/xen/arch/x86/xen.lds.S
+++ b/xen/arch/x86/xen.lds.S
@@ -86,6 +86,9 @@ SECTIONS
. = ALIGN(PAGE_SIZE);
_stextentry = .;
*(.text.entry)
+#ifdef CONFIG_CC_SPLIT_SECTIONS
+ *(.text.entry.*)
+#endif
. = ALIGN(PAGE_SIZE);
_etextentry = .;
@@ -214,6 +217,9 @@ SECTIONS
#endif
_sinittext = .;
*(.init.text)
+#ifdef CONFIG_CC_SPLIT_SECTIONS
+ *(.init.text.*)
+#endif
*(.text.startup)
_einittext = .;
/*
--- a/xen/include/xen/linkage.h
+++ b/xen/include/xen/linkage.h
@@ -21,6 +21,14 @@
#define SYM_ALIGN(algn...) .balign algn
+#if defined(HAVE_AS_SECTNAME_SUBST) && defined(CONFIG_CC_SPLIT_SECTIONS)
+# define SYM_PUSH_SECTION(name, attr) \
+ .pushsection %S.name, attr, %progbits; \
+ .equ .Lsplit_section, 1
+#else
+# define SYM_PUSH_SECTION(name, attr)
+#endif
+
#define SYM_L_GLOBAL(name) .globl name; .hidden name
#define SYM_L_WEAK(name) .weak name
#define SYM_L_LOCAL(name) /* nothing */
@@ -35,7 +43,14 @@
SYM_ALIGN(algn); \
name:
-#define END(name) .size name, . - name
+#define END(name) \
+ .size name, . - name; \
+ .ifdef .Lsplit_section; \
+ .if .Lsplit_section; \
+ .popsection; \
+ .equ .Lsplit_section, 0; \
+ .endif; \
+ .endif
/*
* CODE_FILL in particular may need to expand to nothing (e.g. for RISC-V), in
@@ -49,6 +64,7 @@
#endif
#define FUNC(name, algn...) \
+ SYM_PUSH_SECTION(name, "ax"); \
SYM(name, FUNC, GLOBAL, DO_CODE_ALIGN(algn))
#define LABEL(name, algn...) \
SYM(name, NONE, GLOBAL, DO_CODE_ALIGN(algn))
@@ -56,6 +72,7 @@
SYM(name, DATA, GLOBAL, LASTARG(DATA_ALIGN, ## algn), DATA_FILL)
#define FUNC_LOCAL(name, algn...) \
+ SYM_PUSH_SECTION(name, "ax"); \
SYM(name, FUNC, LOCAL, DO_CODE_ALIGN(algn))
#define LABEL_LOCAL(name, algn...) \
SYM(name, NONE, LOCAL, DO_CODE_ALIGN(algn))
