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[Xen-devel] [RFC v2 5/7] jump_label: port __jump_table to linker tables



Move the __jump_table from the a custom section solution
to a generic solution, this avoiding extra vmlinux.lds.h
customizations.

This also demos the use of the .data (SECTION_DATA)
linker tables and of push_section_tbl().

Signed-off-by: Luis R. Rodriguez <mcgrof@xxxxxxxxxx>
---
 arch/arm/include/asm/jump_label.h     |  4 ++--
 arch/arm64/include/asm/jump_label.h   |  4 ++--
 arch/mips/include/asm/jump_label.h    |  4 ++--
 arch/powerpc/include/asm/jump_label.h |  6 +++---
 arch/s390/include/asm/jump_label.h    |  4 ++--
 arch/sparc/include/asm/jump_label.h   |  4 ++--
 arch/x86/include/asm/jump_label.h     |  9 +++++----
 include/asm-generic/vmlinux.lds.h     |  4 ----
 include/linux/jump_label.h            |  5 +++--
 kernel/jump_label.c                   | 16 +++++++++-------
 kernel/module.c                       |  4 +++-
 11 files changed, 33 insertions(+), 31 deletions(-)

diff --git a/arch/arm/include/asm/jump_label.h 
b/arch/arm/include/asm/jump_label.h
index 34f7b6980d21..c1df4f105df3 100644
--- a/arch/arm/include/asm/jump_label.h
+++ b/arch/arm/include/asm/jump_label.h
@@ -12,7 +12,7 @@ static __always_inline bool arch_static_branch(struct 
static_key *key, bool bran
 {
        asm_volatile_goto("1:\n\t"
                 WASM(nop) "\n\t"
-                ".pushsection __jump_table,  \"aw\"\n\t"
+                push_section_tbl(SECTION_DATA, __jump_table, all, aw)
                 ".word 1b, %l[l_yes], %c0\n\t"
                 ".popsection\n\t"
                 : :  "i" (&((char *)key)[branch]) :  : l_yes);
@@ -26,7 +26,7 @@ static __always_inline bool arch_static_branch_jump(struct 
static_key *key, bool
 {
        asm_volatile_goto("1:\n\t"
                 WASM(b) " %l[l_yes]\n\t"
-                ".pushsection __jump_table,  \"aw\"\n\t"
+                push_section_tbl(SECTION_DATA, __jump_table, all, aw)
                 ".word 1b, %l[l_yes], %c0\n\t"
                 ".popsection\n\t"
                 : :  "i" (&((char *)key)[branch]) :  : l_yes);
diff --git a/arch/arm64/include/asm/jump_label.h 
b/arch/arm64/include/asm/jump_label.h
index 1b5e0e843c3a..18f5ca294eaa 100644
--- a/arch/arm64/include/asm/jump_label.h
+++ b/arch/arm64/include/asm/jump_label.h
@@ -29,7 +29,7 @@
 static __always_inline bool arch_static_branch(struct static_key *key, bool 
branch)
 {
        asm goto("1: nop\n\t"
-                ".pushsection __jump_table,  \"aw\"\n\t"
+                push_section_tbl(SECTION_DATA, __jump_table, all, aw)
                 ".align 3\n\t"
                 ".quad 1b, %l[l_yes], %c0\n\t"
                 ".popsection\n\t"
@@ -43,7 +43,7 @@ l_yes:
 static __always_inline bool arch_static_branch_jump(struct static_key *key, 
bool branch)
 {
        asm goto("1: b %l[l_yes]\n\t"
-                ".pushsection __jump_table,  \"aw\"\n\t"
+                push_section_tbl(SECTION_DATA, __jump_table, all, aw)
                 ".align 3\n\t"
                 ".quad 1b, %l[l_yes], %c0\n\t"
                 ".popsection\n\t"
diff --git a/arch/mips/include/asm/jump_label.h 
b/arch/mips/include/asm/jump_label.h
index e77672539e8e..13e70e290830 100644
--- a/arch/mips/include/asm/jump_label.h
+++ b/arch/mips/include/asm/jump_label.h
@@ -30,7 +30,7 @@ static __always_inline bool arch_static_branch(struct 
static_key *key, bool bran
 {
        asm_volatile_goto("1:\t" NOP_INSN "\n\t"
                "nop\n\t"
-               ".pushsection __jump_table,  \"aw\"\n\t"
+               push_section_tbl(SECTION_DATA, __jump_table, all, aw)
                WORD_INSN " 1b, %l[l_yes], %0\n\t"
                ".popsection\n\t"
                : :  "i" (&((char *)key)[branch]) : : l_yes);
@@ -44,7 +44,7 @@ static __always_inline bool arch_static_branch_jump(struct 
static_key *key, bool
 {
        asm_volatile_goto("1:\tj %l[l_yes]\n\t"
                "nop\n\t"
-               ".pushsection __jump_table,  \"aw\"\n\t"
+               push_section_tbl(SECTION_DATA, __jump_table, all, aw)
                WORD_INSN " 1b, %l[l_yes], %0\n\t"
                ".popsection\n\t"
                : :  "i" (&((char *)key)[branch]) : : l_yes);
diff --git a/arch/powerpc/include/asm/jump_label.h 
b/arch/powerpc/include/asm/jump_label.h
index 47e155f15433..5fffc7b12361 100644
--- a/arch/powerpc/include/asm/jump_label.h
+++ b/arch/powerpc/include/asm/jump_label.h
@@ -22,7 +22,7 @@ static __always_inline bool arch_static_branch(struct 
static_key *key, bool bran
 {
        asm_volatile_goto("1:\n\t"
                 "nop\n\t"
-                ".pushsection __jump_table,  \"aw\"\n\t"
+                push_section_tbl(SECTION_DATA, __jump_table, all, aw)
                 JUMP_ENTRY_TYPE "1b, %l[l_yes], %c0\n\t"
                 ".popsection \n\t"
                 : :  "i" (&((char *)key)[branch]) : : l_yes);
@@ -36,7 +36,7 @@ static __always_inline bool arch_static_branch_jump(struct 
static_key *key, bool
 {
        asm_volatile_goto("1:\n\t"
                 "b %l[l_yes]\n\t"
-                ".pushsection __jump_table,  \"aw\"\n\t"
+                push_section_tbl(SECTION_DATA, __jump_table, all, aw)
                 JUMP_ENTRY_TYPE "1b, %l[l_yes], %c0\n\t"
                 ".popsection \n\t"
                 : :  "i" (&((char *)key)[branch]) : : l_yes);
@@ -61,7 +61,7 @@ struct jump_entry {
 #else
 #define ARCH_STATIC_BRANCH(LABEL, KEY)         \
 1098:  nop;                                    \
-       .pushsection __jump_table, "aw";        \
+       .pushsection .data.tbl.__jump_table.all, "aw";  \
        FTR_ENTRY_LONG 1098b, LABEL, KEY;       \
        .popsection
 #endif
diff --git a/arch/s390/include/asm/jump_label.h 
b/arch/s390/include/asm/jump_label.h
index 7f9fd5e3f1bf..1ebfb7ddcb11 100644
--- a/arch/s390/include/asm/jump_label.h
+++ b/arch/s390/include/asm/jump_label.h
@@ -15,7 +15,7 @@
 static __always_inline bool arch_static_branch(struct static_key *key, bool 
branch)
 {
        asm_volatile_goto("0:   brcl 0,"__stringify(JUMP_LABEL_NOP_OFFSET)"\n"
-               ".pushsection __jump_table, \"aw\"\n"
+               ".pushsection .data.tbl.__jump_table.all, \"aw\"\n"
                ".balign 8\n"
                ".quad 0b, %l[label], %0\n"
                ".popsection\n"
@@ -29,7 +29,7 @@ label:
 static __always_inline bool arch_static_branch_jump(struct static_key *key, 
bool branch)
 {
        asm_volatile_goto("0:   brcl 15, %l[label]\n"
-               ".pushsection __jump_table, \"aw\"\n"
+               ".pushsection .data.tbl.__jump_table.all, \"aw\"\n"
                ".balign 8\n"
                ".quad 0b, %l[label], %0\n"
                ".popsection\n"
diff --git a/arch/sparc/include/asm/jump_label.h 
b/arch/sparc/include/asm/jump_label.h
index 62d0354d1727..848bece455bb 100644
--- a/arch/sparc/include/asm/jump_label.h
+++ b/arch/sparc/include/asm/jump_label.h
@@ -12,7 +12,7 @@ static __always_inline bool arch_static_branch(struct 
static_key *key, bool bran
        asm_volatile_goto("1:\n\t"
                 "nop\n\t"
                 "nop\n\t"
-                ".pushsection __jump_table,  \"aw\"\n\t"
+                push_section_tbl(SECTION_DATA, __jump_table, all, aw)
                 ".align 4\n\t"
                 ".word 1b, %l[l_yes], %c0\n\t"
                 ".popsection \n\t"
@@ -28,7 +28,7 @@ static __always_inline bool arch_static_branch_jump(struct 
static_key *key, bool
        asm_volatile_goto("1:\n\t"
                 "b %l[l_yes]\n\t"
                 "nop\n\t"
-                ".pushsection __jump_table,  \"aw\"\n\t"
+                push_section_tbl(SECTION_DATA, __jump_table, all, aw)
                 ".align 4\n\t"
                 ".word 1b, %l[l_yes], %c0\n\t"
                 ".popsection \n\t"
diff --git a/arch/x86/include/asm/jump_label.h 
b/arch/x86/include/asm/jump_label.h
index adc54c12cbd1..5b80a0e755df 100644
--- a/arch/x86/include/asm/jump_label.h
+++ b/arch/x86/include/asm/jump_label.h
@@ -29,12 +29,13 @@
 
 #include <linux/stringify.h>
 #include <linux/types.h>
+#include <asm-generic/sections.h>
 
 static __always_inline bool arch_static_branch(struct static_key *key, bool 
branch)
 {
        asm_volatile_goto("1:"
                ".byte " __stringify(STATIC_KEY_INIT_NOP) "\n\t"
-               ".pushsection __jump_table,  \"aw\" \n\t"
+               push_section_tbl(SECTION_DATA, __jump_table, all, aw)
                _ASM_ALIGN "\n\t"
                _ASM_PTR "1b, %l[l_yes], %c0 + %c1 \n\t"
                ".popsection \n\t"
@@ -50,7 +51,7 @@ static __always_inline bool arch_static_branch_jump(struct 
static_key *key, bool
        asm_volatile_goto("1:"
                ".byte 0xe9\n\t .long %l[l_yes] - 2f\n\t"
                "2:\n\t"
-               ".pushsection __jump_table,  \"aw\" \n\t"
+               push_section_tbl(SECTION_DATA, __jump_table, all, aw)
                _ASM_ALIGN "\n\t"
                _ASM_PTR "1b, %l[l_yes], %c0 + %c1 \n\t"
                ".popsection \n\t"
@@ -85,7 +86,7 @@ struct jump_entry {
        .else
        .byte           STATIC_KEY_INIT_NOP
        .endif
-       .pushsection __jump_table, "aw"
+       .pushsection .data.tbl.__jump_table.all, "aw"
        _ASM_ALIGN
        _ASM_PTR        .Lstatic_jump_\@, \target, \key
        .popsection
@@ -101,7 +102,7 @@ struct jump_entry {
        .long           \target - .Lstatic_jump_after_\@
 .Lstatic_jump_after_\@:
        .endif
-       .pushsection __jump_table, "aw"
+       .pushsection .data.tbl.__jump_table.all, "aw"
        _ASM_ALIGN
        _ASM_PTR        .Lstatic_jump_\@, \target, \key + 1
        .popsection
diff --git a/include/asm-generic/vmlinux.lds.h 
b/include/asm-generic/vmlinux.lds.h
index 91815fb1f2fa..11e1adcbcb24 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -210,10 +210,6 @@
        STRUCT_ALIGN();                                                 \
        *(__tracepoints)                                                \
        /* implement dynamic printk debug */                            \
-       . = ALIGN(8);                                                   \
-       VMLINUX_SYMBOL(__start___jump_table) = .;                       \
-       *(__jump_table)                                                 \
-       VMLINUX_SYMBOL(__stop___jump_table) = .;                        \
        . = ALIGN(8);                                                   \
        VMLINUX_SYMBOL(__start___verbose) = .;                          \
        *(__verbose)                                                    \
diff --git a/include/linux/jump_label.h b/include/linux/jump_label.h
index 0536524bb9eb..42b68b1e4a39 100644
--- a/include/linux/jump_label.h
+++ b/include/linux/jump_label.h
@@ -1,6 +1,8 @@
 #ifndef _LINUX_JUMP_LABEL_H
 #define _LINUX_JUMP_LABEL_H
 
+#include <linux/tables.h>
+
 /*
  * Jump label support
  *
@@ -138,8 +140,7 @@ static __always_inline bool static_key_true(struct 
static_key *key)
        return !arch_static_branch(key, true);
 }
 
-extern struct jump_entry __start___jump_table[];
-extern struct jump_entry __stop___jump_table[];
+DECLARE_LINKTABLE_DATA(struct jump_entry, __jump_table);
 
 extern void jump_label_init(void);
 extern void jump_label_lock(void);
diff --git a/kernel/jump_label.c b/kernel/jump_label.c
index 05254eeb4b4e..66d6e24148be 100644
--- a/kernel/jump_label.c
+++ b/kernel/jump_label.c
@@ -17,6 +17,8 @@
 
 #ifdef HAVE_JUMP_LABEL
 
+DEFINE_LINKTABLE_DATA(struct jump_entry, __jump_table);
+
 /* mutex to protect coming/going of the the jump_label table */
 static DEFINE_MUTEX(jump_label_mutex);
 
@@ -200,15 +202,14 @@ static void __jump_label_update(struct static_key *key,
 
 void __init jump_label_init(void)
 {
-       struct jump_entry *iter_start = __start___jump_table;
-       struct jump_entry *iter_stop = __stop___jump_table;
        struct static_key *key = NULL;
        struct jump_entry *iter;
 
        jump_label_lock();
-       jump_label_sort_entries(iter_start, iter_stop);
+       jump_label_sort_entries(LINKTABLE_START(__jump_table),
+                               LINKTABLE_END(__jump_table));
 
-       for (iter = iter_start; iter < iter_stop; iter++) {
+       LINKTABLE_FOR_EACH(iter, __jump_table) {
                struct static_key *iterk;
 
                /* rewrite NOPs */
@@ -450,8 +451,9 @@ early_initcall(jump_label_init_module);
  */
 int jump_label_text_reserved(void *start, void *end)
 {
-       int ret = __jump_label_text_reserved(__start___jump_table,
-                       __stop___jump_table, start, end);
+       int ret = __jump_label_text_reserved(LINKTABLE_START(__jump_table),
+                                            LINKTABLE_END(__jump_table),
+                                            start, end);
 
        if (ret)
                return ret;
@@ -464,7 +466,7 @@ int jump_label_text_reserved(void *start, void *end)
 
 static void jump_label_update(struct static_key *key)
 {
-       struct jump_entry *stop = __stop___jump_table;
+       struct jump_entry *stop = LINKTABLE_END(__jump_table);
        struct jump_entry *entry = static_key_entries(key);
 #ifdef CONFIG_MODULES
        struct module *mod;
diff --git a/kernel/module.c b/kernel/module.c
index 9537da37ce87..42249ee8e462 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -2930,7 +2930,9 @@ static int find_module_sections(struct module *mod, 
struct load_info *info)
                                             &mod->num_tracepoints);
 #endif
 #ifdef HAVE_JUMP_LABEL
-       mod->jump_entries = section_objs(info, "__jump_table",
+       mod->jump_entries = section_objs(info,
+                                       SECTION_TBL(SECTION_DATA,
+                                                   __jump_table,),
                                        sizeof(*mod->jump_entries),
                                        &mod->num_jump_entries);
 #endif
-- 
2.7.0


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