| Message ID | 20230217174814.1006961-4-andrew.cooper3@citrix.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | x86/kexec: ASM improvements | expand |
On 17.02.2023 18:48, Andrew Cooper wrote: > @@ -90,7 +91,10 @@ ENTRY(kexec_reloc) > push %rax > lretq > > -relocate_pages: > + .type kexec_reloc, @function > + .size kexec_reloc, . - kexec_reloc > + > +ENTRY(relocate_pages) > /* %rdi - indirection page maddr */ > pushq %rbx > > @@ -137,9 +141,12 @@ relocate_pages: > popq %rbx > ret > > + .type relocate_pages, @function > + .size relocate_pages, . - relocate_pages > + > .code32 > > -compatibility_mode: > +ENTRY(compatibility_mode) Do you really mean to make both labels global, thus potentially risking a link-time name collision down the road? In C files we try to move the other direction after all, making symbols static which can be. > @@ -167,7 +174,14 @@ compatibility_mode: > call *%ebp > ud2 > > - .align 4 > + .type compatibility_mode, @function > + .size compatibility_mode, . - compatibility_mode > + > + /* > + * Ensure data is in a different cache line to code. > + */ Nit (style): Strictly speaking this is a single-line comment. Jan > + .align SMP_CACHE_BYTES, 0 > + > compat_mode_gdt_desc: > .word .Lcompat_mode_gdt_end - compat_mode_gdt -1 > .quad . - kexec_reloc /* Relocated before use */
diff --git a/xen/arch/x86/x86_64/kexec_reloc.S b/xen/arch/x86/x86_64/kexec_reloc.S index a81f64146190..c7fc11fa5868 100644 --- a/xen/arch/x86/x86_64/kexec_reloc.S +++ b/xen/arch/x86/x86_64/kexec_reloc.S @@ -13,6 +13,7 @@ .file __FILE__ +#include <xen/cache.h> #include <xen/kimage.h> #include <asm/asm_defns.h> @@ -90,7 +91,10 @@ ENTRY(kexec_reloc) push %rax lretq -relocate_pages: + .type kexec_reloc, @function + .size kexec_reloc, . - kexec_reloc + +ENTRY(relocate_pages) /* %rdi - indirection page maddr */ pushq %rbx @@ -137,9 +141,12 @@ relocate_pages: popq %rbx ret + .type relocate_pages, @function + .size relocate_pages, . - relocate_pages + .code32 -compatibility_mode: +ENTRY(compatibility_mode) /* Setup some sane segments. */ movl $0x0008, %eax movl %eax, %ds @@ -167,7 +174,14 @@ compatibility_mode: call *%ebp ud2 - .align 4 + .type compatibility_mode, @function + .size compatibility_mode, . - compatibility_mode + + /* + * Ensure data is in a different cache line to code. + */ + .align SMP_CACHE_BYTES, 0 + compat_mode_gdt_desc: .word .Lcompat_mode_gdt_end - compat_mode_gdt -1 .quad . - kexec_reloc /* Relocated before use */
All of kexec_reloc(), relocate_pages() and compatibility_mode() are function-like. Annotate them appropriately. Furthermore, move the data into a different cacheline from the code, so the relocation of compat_mode_gdt_desc doesn't trigger self-modifying safety logic in the pipeline. No functional change. Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com> --- CC: Jan Beulich <JBeulich@suse.com> CC: Roger Pau Monné <roger.pau@citrix.com> CC: Wei Liu <wl@xen.org> --- xen/arch/x86/x86_64/kexec_reloc.S | 20 +++++++++++++++++--- 1 file changed, 17 insertions(+), 3 deletions(-)