| Message ID | 1469222687-1600-11-git-send-email-mcgrof@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Fri, Jul 22, 2016 at 02:24:44PM -0700, Luis R. Rodriguez wrote: > diff --git a/tools/objtool/special.c b/tools/objtool/special.c > index bff8abb3a4aa..f0ad369f994b 100644 > --- a/tools/objtool/special.c > +++ b/tools/objtool/special.c > @@ -26,6 +26,10 @@ > #include "special.h" > #include "warn.h" > > +#include "../../include/asm-generic/sections.h" > +#include "../../include/asm-generic/tables.h" > +#include "../../include/linux/stringify.h" > + > #define EX_ENTRY_SIZE 12 > #define EX_ORIG_OFFSET 0 > #define EX_NEW_OFFSET 4 > @@ -63,7 +67,9 @@ struct special_entry entries[] = { > .feature = ALT_FEATURE_OFFSET, > }, > { > - .sec = "__jump_table", > + .sec = __stringify(SECTION_TBL(SECTION_DATA, > + __jump_table, > + SECTION_ORDER_ANY)), > .jump_or_nop = true, > .size = JUMP_ENTRY_SIZE, > .orig = JUMP_ORIG_OFFSET, (continuing our discussion from another thread...) I think tools code isn't allowed to include kernel files because the tools subdirectory is supposed to be completely independent. As far as I can tell, the section name will always be ".data.tbl.__jump_table.any". Is that true? If so, any reason why we can't just hard-code the string here? As you saw, if the string changes, objtool will complain and 0-day will report it.
On Fri, Jul 22, 2016 at 04:49:45PM -0500, Josh Poimboeuf wrote: > On Fri, Jul 22, 2016 at 02:24:44PM -0700, Luis R. Rodriguez wrote: > > diff --git a/tools/objtool/special.c b/tools/objtool/special.c > > index bff8abb3a4aa..f0ad369f994b 100644 > > --- a/tools/objtool/special.c > > +++ b/tools/objtool/special.c > > @@ -26,6 +26,10 @@ > > #include "special.h" > > #include "warn.h" > > > > +#include "../../include/asm-generic/sections.h" > > +#include "../../include/asm-generic/tables.h" > > +#include "../../include/linux/stringify.h" > > + > > #define EX_ENTRY_SIZE 12 > > #define EX_ORIG_OFFSET 0 > > #define EX_NEW_OFFSET 4 > > @@ -63,7 +67,9 @@ struct special_entry entries[] = { > > .feature = ALT_FEATURE_OFFSET, > > }, > > { > > - .sec = "__jump_table", > > + .sec = __stringify(SECTION_TBL(SECTION_DATA, > > + __jump_table, > > + SECTION_ORDER_ANY)), > > .jump_or_nop = true, > > .size = JUMP_ENTRY_SIZE, > > .orig = JUMP_ORIG_OFFSET, > > (continuing our discussion from another thread...) > > I think tools code isn't allowed to include kernel files because the > tools subdirectory is supposed to be completely independent. That was also the case for userpsace tools in scripts/ -- for instance scripts/mod/modpost.c made an exception. What I've proposed here to keep things simple was to ensure -UKERNEL is passed and then only include files we know will work. Refer to the patch "kprobes: port .kprobes.text to section range" in this series for an extension of the scripts/mod/modpost.c kernel headers use. > As far as I can tell, the section name will always be > ".data.tbl.__jump_table.any". Is that true? If so, any reason why we > can't just hard-code the string here? Its a fair strategy, however if upstream changes the order name we'd have to hand code this as well, by using a macro we keep it all in one place. > As you saw, if the string > changes, objtool will complain and 0-day will report it. Indeed, which is why I was hoping to instead stick to a standard sections set of header files that lets us get these in on place. The only place I hand coded in this series was in the perl file scripts/recordmcount.pl but I suppose if we wanted to get creative we could even generate a header for it too. If we want to avoid all this hacker include stuff another option is to *generate* each respective sections.h for the kernel, and also, one for tools, and one for perl. What do you think? Luis
On Sat, Jul 23, 2016 at 12:26:54AM +0200, Luis R. Rodriguez wrote: > On Fri, Jul 22, 2016 at 04:49:45PM -0500, Josh Poimboeuf wrote: > > On Fri, Jul 22, 2016 at 02:24:44PM -0700, Luis R. Rodriguez wrote: > > > diff --git a/tools/objtool/special.c b/tools/objtool/special.c > > > index bff8abb3a4aa..f0ad369f994b 100644 > > > --- a/tools/objtool/special.c > > > +++ b/tools/objtool/special.c > > > @@ -26,6 +26,10 @@ > > > #include "special.h" > > > #include "warn.h" > > > > > > +#include "../../include/asm-generic/sections.h" > > > +#include "../../include/asm-generic/tables.h" > > > +#include "../../include/linux/stringify.h" > > > + > > > #define EX_ENTRY_SIZE 12 > > > #define EX_ORIG_OFFSET 0 > > > #define EX_NEW_OFFSET 4 > > > @@ -63,7 +67,9 @@ struct special_entry entries[] = { > > > .feature = ALT_FEATURE_OFFSET, > > > }, > > > { > > > - .sec = "__jump_table", > > > + .sec = __stringify(SECTION_TBL(SECTION_DATA, > > > + __jump_table, > > > + SECTION_ORDER_ANY)), > > > .jump_or_nop = true, > > > .size = JUMP_ENTRY_SIZE, > > > .orig = JUMP_ORIG_OFFSET, > > > > (continuing our discussion from another thread...) > > > > I think tools code isn't allowed to include kernel files because the > > tools subdirectory is supposed to be completely independent. > > That was also the case for userpsace tools in scripts/ -- for instance > scripts/mod/modpost.c made an exception. What I've proposed here to > keep things simple was to ensure -UKERNEL is passed and then only > include files we know will work. > > Refer to the patch "kprobes: port .kprobes.text to section range" > in this series for an extension of the scripts/mod/modpost.c kernel > headers use. I think the rule of separating code is stricter for tools/ than it is for scripts/. The scripts are generally kernel-specific whereas the tools are independent. I believe the goal is to be able to copy them out of the kernel tree and still be able to compile them. > > As far as I can tell, the section name will always be > > ".data.tbl.__jump_table.any". Is that true? If so, any reason why we > > can't just hard-code the string here? > > Its a fair strategy, however if upstream changes the order name we'd > have to hand code this as well, by using a macro we keep it all in one > place. Hm, do you expect the section name to change often? > > As you saw, if the string > > changes, objtool will complain and 0-day will report it. > > Indeed, which is why I was hoping to instead stick to a standard > sections set of header files that lets us get these in on place. Actually, I meant that obtool reporting the change would be a good thing, in favor of just hard-coding the string. It lets objtool do its job of letting us know when something changes, like it did today. > The only place I hand coded in this series was in the perl > file scripts/recordmcount.pl but I suppose if we wanted to get > creative we could even generate a header for it too. > > If we want to avoid all this hacker include stuff another option > is to *generate* each respective sections.h for the kernel, and > also, one for tools, and one for perl. What do you think? If the generated files aren't checked into git, tools/ will rely on kernel files and will no longer be independent. If they *are* checked in, then we have to keep the files in sync. Either way it sounds like overkill, just to avoid hard-coding a string for which objtool will already warn if it changes.
On Fri, Jul 22, 2016 at 05:55:35PM -0500, Josh Poimboeuf wrote: > On Sat, Jul 23, 2016 at 12:26:54AM +0200, Luis R. Rodriguez wrote: > > On Fri, Jul 22, 2016 at 04:49:45PM -0500, Josh Poimboeuf wrote: > > > On Fri, Jul 22, 2016 at 02:24:44PM -0700, Luis R. Rodriguez wrote: > > > > diff --git a/tools/objtool/special.c b/tools/objtool/special.c > > > > index bff8abb3a4aa..f0ad369f994b 100644 > > > > --- a/tools/objtool/special.c > > > > +++ b/tools/objtool/special.c > > > > @@ -26,6 +26,10 @@ > > > > #include "special.h" > > > > #include "warn.h" > > > > > > > > +#include "../../include/asm-generic/sections.h" > > > > +#include "../../include/asm-generic/tables.h" > > > > +#include "../../include/linux/stringify.h" > > > > + > > > > #define EX_ENTRY_SIZE 12 > > > > #define EX_ORIG_OFFSET 0 > > > > #define EX_NEW_OFFSET 4 > > > > @@ -63,7 +67,9 @@ struct special_entry entries[] = { > > > > .feature = ALT_FEATURE_OFFSET, > > > > }, > > > > { > > > > - .sec = "__jump_table", > > > > + .sec = __stringify(SECTION_TBL(SECTION_DATA, > > > > + __jump_table, > > > > + SECTION_ORDER_ANY)), > > > > .jump_or_nop = true, > > > > .size = JUMP_ENTRY_SIZE, > > > > .orig = JUMP_ORIG_OFFSET, > > > > > > (continuing our discussion from another thread...) > > > > > > I think tools code isn't allowed to include kernel files because the > > > tools subdirectory is supposed to be completely independent. > > > > That was also the case for userpsace tools in scripts/ -- for instance > > scripts/mod/modpost.c made an exception. What I've proposed here to > > keep things simple was to ensure -UKERNEL is passed and then only > > include files we know will work. > > > > Refer to the patch "kprobes: port .kprobes.text to section range" > > in this series for an extension of the scripts/mod/modpost.c kernel > > headers use. > > I think the rule of separating code is stricter for tools/ than it is > for scripts/. The scripts are generally kernel-specific whereas the > tools are independent. I believe the goal is to be able to copy them > out of the kernel tree and still be able to compile them. I see. > > > As far as I can tell, the section name will always be > > > ".data.tbl.__jump_table.any". Is that true? If so, any reason why we > > > can't just hard-code the string here? > > > > Its a fair strategy, however if upstream changes the order name we'd > > have to hand code this as well, by using a macro we keep it all in one > > place. > > Hm, do you expect the section name to change often? Nope, if anything only upon deployment on major distributions due to some perhaps compatibility thing with custom hacks folks may have carried and this just ended up clashing with. The only other case I can think of a need for a change would be if upstream linkers supported something similar for another brand of section names, with the added gain that we would then not even need the 2 new lines on the kernel linker script for section ranges and tables per section. > > > As you saw, if the string > > > changes, objtool will complain and 0-day will report it. > > > > Indeed, which is why I was hoping to instead stick to a standard > > sections set of header files that lets us get these in on place. > > Actually, I meant that obtool reporting the change would be a good > thing, in favor of just hard-coding the string. It lets objtool do its > job of letting us know when something changes, like it did today. Getting a report so you can fix something is one reason to have a tool, having it so you can inspect changes is another. So it depends what uses there are for objtool. I take it that for this case we do want upstream objtool to embrace the new section name to avoid further reports as issues ? > > The only place I hand coded in this series was in the perl > > file scripts/recordmcount.pl but I suppose if we wanted to get > > creative we could even generate a header for it too. > > > > If we want to avoid all this hacker include stuff another option > > is to *generate* each respective sections.h for the kernel, and > > also, one for tools, and one for perl. What do you think? > > If the generated files aren't checked into git, tools/ will rely on > kernel files and will no longer be independent. If they *are* checked > in, then we have to keep the files in sync. Either way it sounds like > overkill, just to avoid hard-coding a string for which objtool will > already warn if it changes. We can open code the string, that's fine. In retrospect since things won't change often that keeps things simple. Luis
diff --git a/arch/arm/include/asm/jump_label.h b/arch/arm/include/asm/jump_label.h index 34f7b6980d21..960135a7b88e 100644 --- a/arch/arm/include/asm/jump_label.h +++ b/arch/arm/include/asm/jump_label.h @@ -1,6 +1,8 @@ #ifndef _ASM_ARM_JUMP_LABEL_H #define _ASM_ARM_JUMP_LABEL_H +#include <asm/tables.h> + #ifndef __ASSEMBLY__ #include <linux/types.h> @@ -12,7 +14,7 @@ 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_any(SECTION_DATA, __jump_table, aw) ".word 1b, %l[l_yes], %c0\n\t" ".popsection\n\t" : : "i" (&((char *)key)[branch]) : : l_yes); @@ -26,7 +28,7 @@ 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_any(SECTION_DATA, __jump_table, 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..aa52cd2607e3 100644 --- a/arch/arm64/include/asm/jump_label.h +++ b/arch/arm64/include/asm/jump_label.h @@ -19,6 +19,8 @@ #ifndef __ASM_JUMP_LABEL_H #define __ASM_JUMP_LABEL_H +#include <asm/tables.h> + #ifndef __ASSEMBLY__ #include <linux/types.h> @@ -29,7 +31,7 @@ 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_any(SECTION_DATA, __jump_table, aw) ".align 3\n\t" ".quad 1b, %l[l_yes], %c0\n\t" ".popsection\n\t" @@ -43,7 +45,7 @@ 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_any(SECTION_DATA, __jump_table, 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..78e70cb98592 100644 --- a/arch/mips/include/asm/jump_label.h +++ b/arch/mips/include/asm/jump_label.h @@ -8,6 +8,8 @@ #ifndef _ASM_MIPS_JUMP_LABEL_H #define _ASM_MIPS_JUMP_LABEL_H +#include <asm/tables.h> + #ifndef __ASSEMBLY__ #include <linux/types.h> @@ -30,7 +32,7 @@ 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_any(SECTION_DATA, __jump_table, aw) WORD_INSN " 1b, %l[l_yes], %0\n\t" ".popsection\n\t" : : "i" (&((char *)key)[branch]) : : l_yes); @@ -44,7 +46,7 @@ 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_any(SECTION_DATA, __jump_table, 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 9af103a23975..bf68a8766773 100644 --- a/arch/powerpc/include/asm/jump_label.h +++ b/arch/powerpc/include/asm/jump_label.h @@ -10,6 +10,8 @@ * 2 of the License, or (at your option) any later version. */ +#include <asm/tables.h> + #ifndef __ASSEMBLY__ #include <linux/types.h> @@ -23,7 +25,7 @@ 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_any(SECTION_DATA, __jump_table, aw) JUMP_ENTRY_TYPE "1b, %l[l_yes], %c0\n\t" ".popsection \n\t" : : "i" (&((char *)key)[branch]) : : l_yes); @@ -37,7 +39,7 @@ 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_any(SECTION_DATA, __jump_table, aw) JUMP_ENTRY_TYPE "1b, %l[l_yes], %c0\n\t" ".popsection \n\t" : : "i" (&((char *)key)[branch]) : : l_yes); @@ -62,7 +64,7 @@ struct jump_entry { #else #define ARCH_STATIC_BRANCH(LABEL, KEY) \ 1098: nop; \ - .pushsection __jump_table, "aw"; \ + push_section_tbl_any(SECTION_DATA, __jump_table, 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 9be198f5ee79..17f02aec4644 100644 --- a/arch/s390/include/asm/jump_label.h +++ b/arch/s390/include/asm/jump_label.h @@ -1,6 +1,8 @@ #ifndef _ASM_S390_JUMP_LABEL_H #define _ASM_S390_JUMP_LABEL_H +#include <asm/tables.h> + #ifndef __ASSEMBLY__ #include <linux/types.h> @@ -16,7 +18,7 @@ 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" + push_section_tbl_any(SECTION_DATA, __jump_table, aw) ".balign 8\n" ".quad 0b, %l[label], %0\n" ".popsection\n" @@ -30,7 +32,7 @@ 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" + push_section_tbl_any(SECTION_DATA, __jump_table, aw) ".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..dde1275233f7 100644 --- a/arch/sparc/include/asm/jump_label.h +++ b/arch/sparc/include/asm/jump_label.h @@ -1,6 +1,8 @@ #ifndef _ASM_SPARC_JUMP_LABEL_H #define _ASM_SPARC_JUMP_LABEL_H +#include <asm/tables.h> + #ifndef __ASSEMBLY__ #include <linux/types.h> @@ -12,7 +14,7 @@ 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_any(SECTION_DATA, __jump_table, aw) ".align 4\n\t" ".word 1b, %l[l_yes], %c0\n\t" ".popsection \n\t" @@ -28,7 +30,7 @@ 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_any(SECTION_DATA, __jump_table, 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..d25fafa3df4b 100644 --- a/arch/x86/include/asm/jump_label.h +++ b/arch/x86/include/asm/jump_label.h @@ -1,6 +1,8 @@ #ifndef _ASM_X86_JUMP_LABEL_H #define _ASM_X86_JUMP_LABEL_H +#include <asm/tables.h> + #ifndef HAVE_JUMP_LABEL /* * For better or for worse, if jump labels (the gcc extension) are missing, @@ -34,7 +36,7 @@ static __always_inline bool arch_static_branch(struct static_key *key, bool bran { asm_volatile_goto("1:" ".byte " __stringify(STATIC_KEY_INIT_NOP) "\n\t" - ".pushsection __jump_table, \"aw\" \n\t" + push_section_tbl_any(SECTION_DATA, __jump_table, aw) _ASM_ALIGN "\n\t" _ASM_PTR "1b, %l[l_yes], %c0 + %c1 \n\t" ".popsection \n\t" @@ -50,7 +52,7 @@ 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_any(SECTION_DATA, __jump_table, aw) _ASM_ALIGN "\n\t" _ASM_PTR "1b, %l[l_yes], %c0 + %c1 \n\t" ".popsection \n\t" @@ -85,7 +87,7 @@ struct jump_entry { .else .byte STATIC_KEY_INIT_NOP .endif - .pushsection __jump_table, "aw" + push_section_tbl_any(SECTION_DATA, __jump_table, aw) _ASM_ALIGN _ASM_PTR .Lstatic_jump_\@, \target, \key .popsection @@ -101,7 +103,7 @@ struct jump_entry { .long \target - .Lstatic_jump_after_\@ .Lstatic_jump_after_\@: .endif - .pushsection __jump_table, "aw" + push_section_tbl_any(SECTION_DATA, __jump_table, 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 8e31a4454841..e186432a82e6 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 661af564fae8..e6acdd8cd62b 100644 --- a/include/linux/jump_label.h +++ b/include/linux/jump_label.h @@ -130,8 +130,10 @@ 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[]; +#ifndef __KERNEL__ + #include <linux/tables.h> + DECLARE_LINKTABLE(struct jump_entry, __jump_table); +#endif /* __KERNEL__ */ extern void jump_label_init(void); extern void jump_label_lock(void); @@ -384,6 +386,6 @@ extern bool ____wrong_branch_error(void); #define static_branch_enable(x) static_key_enable(&(x)->key) #define static_branch_disable(x) static_key_disable(&(x)->key) -#endif /* _LINUX_JUMP_LABEL_H */ - #endif /* __ASSEMBLY__ */ + +#endif /* _LINUX_JUMP_LABEL_H */ diff --git a/kernel/jump_label.c b/kernel/jump_label.c index f19aa02a8f48..72dd2026ea3f 100644 --- a/kernel/jump_label.c +++ b/kernel/jump_label.c @@ -15,9 +15,12 @@ #include <linux/static_key.h> #include <linux/jump_label_ratelimit.h> #include <linux/bug.h> +#include <linux/tables.h> #ifdef HAVE_JUMP_LABEL +DEFINE_LINKTABLE(struct jump_entry, __jump_table); + /* mutex to protect coming/going of the the jump_label table */ static DEFINE_MUTEX(jump_label_mutex); @@ -274,8 +277,6 @@ 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; @@ -289,9 +290,10 @@ void __init jump_label_init(void) BUILD_BUG_ON((int)ATOMIC_INIT(1) != 1); jump_label_lock(); - jump_label_sort_entries(iter_start, iter_stop); + jump_label_sort_entries(LINUX_SECTION_START(__jump_table), + LINUX_SECTION_END(__jump_table)); - for (iter = iter_start; iter < iter_stop; iter++) { + LINKTABLE_FOR_EACH(iter, __jump_table) { struct static_key *iterk; /* rewrite NOPs */ @@ -533,8 +535,9 @@ 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(LINUX_SECTION_START(__jump_table), + LINUX_SECTION_END(__jump_table), + start, end); if (ret) return ret; @@ -547,7 +550,7 @@ 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 = LINUX_SECTION_END(__jump_table); struct jump_entry *entry = static_key_entries(key); #ifdef CONFIG_MODULES struct module *mod; diff --git a/scripts/module-common.lds.S b/scripts/module-common.lds.S index 73a2c7da0e55..d51140103ece 100644 --- a/scripts/module-common.lds.S +++ b/scripts/module-common.lds.S @@ -3,6 +3,10 @@ * Archs are free to supply their own linker scripts. ld will * combine them automatically. */ + +#include <asm/sections.h> +#include <asm/tables.h> + SECTIONS { /DISCARD/ : { *(.discard) } @@ -16,6 +20,7 @@ SECTIONS { __kcrctab_unused 0 : { *(SORT(___kcrctab_unused+*)) } __kcrctab_unused_gpl 0 : { *(SORT(___kcrctab_unused_gpl+*)) } __kcrctab_gpl_future 0 : { *(SORT(___kcrctab_gpl_future+*)) } + __jump_table 0 : { *(SORT(SECTION_TBL(SECTION_DATA, __jump_table, *))) } . = ALIGN(8); .init_array 0 : { *(SORT(.init_array.*)) *(.init_array) } diff --git a/tools/objtool/special.c b/tools/objtool/special.c index bff8abb3a4aa..f0ad369f994b 100644 --- a/tools/objtool/special.c +++ b/tools/objtool/special.c @@ -26,6 +26,10 @@ #include "special.h" #include "warn.h" +#include "../../include/asm-generic/sections.h" +#include "../../include/asm-generic/tables.h" +#include "../../include/linux/stringify.h" + #define EX_ENTRY_SIZE 12 #define EX_ORIG_OFFSET 0 #define EX_NEW_OFFSET 4 @@ -63,7 +67,9 @@ struct special_entry entries[] = { .feature = ALT_FEATURE_OFFSET, }, { - .sec = "__jump_table", + .sec = __stringify(SECTION_TBL(SECTION_DATA, + __jump_table, + SECTION_ORDER_ANY)), .jump_or_nop = true, .size = JUMP_ENTRY_SIZE, .orig = JUMP_ORIG_OFFSET,
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 table and of the shared asm call push_section_tbl(). Built-in kernel functionality was tested with CONFIG_STATIC_KEYS_SELFTEST. Moduler kernel functionality was tested with CONFIG_TEST_STATIC_KEYS. Both work as expected. Since __jump_table sections are also supported per module this also required expanding module-common.lds.S to capture and fold all .data.tlb.__jump_table.* onto the the section __jump_table -- in this case for modules need to keep a reference in place, given the alternative is to use DEFINE_LINKTABLE(struct jump_entry, __jump_table) per module -- and later through macro hacks instantiate the jump entries per module upon init. This is doable but we'd loose out on the sorting of the table using the linker, to sort we'd always still need to expand the module common linker script. An alternative mechanism is possible which would make these custom module sections extensions dynamic without requiring manual changes, this however is best done later through a separate evolution once linker tables are in place. A careful reviewer may note that some architectures use "\n\t" to separate asm code, while others just use a new line. Upon review last time it was deemed reasonable to for all architectures to juse use "\n", this is defined as ASM_CMD_SEP, and if an architecture needs to override they can do so on their architecture sections.h prior to including asm-generic/sections.h v3: o More elaborate tests performed o first modular support use case, module tested was CONFIG_TEST_STATIC_KEYS (lib/test_static_keys.ko), this required us to extend module-common.lds.S o use generic push_section_tbl_any() for all architectures o Makes use of ASM_CMD_SEP to enable architectures to override later if needed o guard tables.h inclusion and table definition with __KERNEL__ v2: introduced in this series Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org> --- arch/arm/include/asm/jump_label.h | 6 ++++-- arch/arm64/include/asm/jump_label.h | 6 ++++-- arch/mips/include/asm/jump_label.h | 6 ++++-- arch/powerpc/include/asm/jump_label.h | 8 +++++--- arch/s390/include/asm/jump_label.h | 6 ++++-- arch/sparc/include/asm/jump_label.h | 6 ++++-- arch/x86/include/asm/jump_label.h | 10 ++++++---- include/asm-generic/vmlinux.lds.h | 4 ---- include/linux/jump_label.h | 10 ++++++---- kernel/jump_label.c | 17 ++++++++++------- scripts/module-common.lds.S | 5 +++++ tools/objtool/special.c | 8 +++++++- 12 files changed, 59 insertions(+), 33 deletions(-)