The following commit has been merged into the objtool/core branch of tip: Commit-ID: b7b205c3a0bc2b51f83cb793178ccbc12addf275 Gitweb: https://git.kernel.org/tip/b7b205c3a0bc2b51f83cb793178ccbc12addf275 Author: Josh Poimboeuf <jpoimboe@xxxxxxxxxx> AuthorDate: Fri, 20 Aug 2021 12:31:07 -07:00 Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx> CommitterDate: Wed, 15 Sep 2021 15:51:44 +02:00 x86/xen: Move hypercall_page to top of the file Because hypercall_page is page-aligned, the assembler inexplicably adds an unreachable jump from after the end of the previous code to the beginning of hypercall_page. That confuses objtool, understandably. It also creates significant text fragmentation. As a result, much of the object file is wasted text (nops). Move hypercall_page to the beginning of the file to both prevent the text fragmentation and avoid the dead jump instruction. $ size /tmp/head_64.before.o /tmp/head_64.after.o text data bss dec hex filename 10924 307252 4096 322272 4eae0 /tmp/head_64.before.o 6823 307252 4096 318171 4dadb /tmp/head_64.after.o Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Reviewed-by: Juergen Gross <jgross@xxxxxxxx> Link: https://lkml.kernel.org/r/20210820193107.omvshmsqbpxufzkc@treble --- arch/x86/xen/xen-head.S | 34 +++++++++++++++++----------------- 1 file changed, 17 insertions(+), 17 deletions(-) diff --git a/arch/x86/xen/xen-head.S b/arch/x86/xen/xen-head.S index cb6538a..488944d 100644 --- a/arch/x86/xen/xen-head.S +++ b/arch/x86/xen/xen-head.S @@ -20,6 +20,23 @@ #include <xen/interface/xen-mca.h> #include <asm/xen/interface.h> +.pushsection .text + .balign PAGE_SIZE +SYM_CODE_START(hypercall_page) + .rept (PAGE_SIZE / 32) + UNWIND_HINT_FUNC + .skip 31, 0x90 + ret + .endr + +#define HYPERCALL(n) \ + .equ xen_hypercall_##n, hypercall_page + __HYPERVISOR_##n * 32; \ + .type xen_hypercall_##n, @function; .size xen_hypercall_##n, 32 +#include <asm/xen-hypercalls.h> +#undef HYPERCALL +SYM_CODE_END(hypercall_page) +.popsection + #ifdef CONFIG_XEN_PV __INIT SYM_CODE_START(startup_xen) @@ -64,23 +81,6 @@ SYM_CODE_END(asm_cpu_bringup_and_idle) #endif #endif -.pushsection .text - .balign PAGE_SIZE -SYM_CODE_START(hypercall_page) - .rept (PAGE_SIZE / 32) - UNWIND_HINT_FUNC - .skip 31, 0x90 - ret - .endr - -#define HYPERCALL(n) \ - .equ xen_hypercall_##n, hypercall_page + __HYPERVISOR_##n * 32; \ - .type xen_hypercall_##n, @function; .size xen_hypercall_##n, 32 -#include <asm/xen-hypercalls.h> -#undef HYPERCALL -SYM_CODE_END(hypercall_page) -.popsection - ELFNOTE(Xen, XEN_ELFNOTE_GUEST_OS, .asciz "linux") ELFNOTE(Xen, XEN_ELFNOTE_GUEST_VERSION, .asciz "2.6") ELFNOTE(Xen, XEN_ELFNOTE_XEN_VERSION, .asciz "xen-3.0")
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