diff options
| author | Josh Poimboeuf <jpoimboe@redhat.com> | 2021-08-20 12:31:07 -0700 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2021-09-15 15:51:44 +0200 |
| commit | b7b205c3a0bc2b51f83cb793178ccbc12addf275 (patch) | |
| tree | 6cab1bfd99a35987d24f692ee218d91e2fae56bb /arch/x86/xen/xen-head.S | |
| parent | 9af9dcf11bda3e2c0e24c1acaacb8685ad974e93 (diff) | |
| download | linux-b7b205c3a0bc2b51f83cb793178ccbc12addf275.tar.bz2 | |
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@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lkml.kernel.org/r/20210820193107.omvshmsqbpxufzkc@treble
Diffstat (limited to 'arch/x86/xen/xen-head.S')
| -rw-r--r-- | arch/x86/xen/xen-head.S | 34 |
1 files changed, 17 insertions, 17 deletions
diff --git a/arch/x86/xen/xen-head.S b/arch/x86/xen/xen-head.S index cb6538ae2fe0..488944d6d430 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") |