x86/paravirt: Ensure proper alignment

The entries in the .parainstructions sections are 8 byte aligned and the
corresponding C struct paravirt_patch_site makes the array offset 16
bytes.

Though the pushed entries are only using 12 bytes, __parainstructions_end
is therefore 4 bytes short.

That works by chance because it's only used in a loop:

     for (p = start; p < end; p++)

But this falls flat when calculating the number of elements:

    n = end - start

That's obviously off by one.

Ensure that the gap is filled and the last entry is occupying 16 bytes.

  [ bp: Add the proper struct and section names. ]

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/20220915111142.992398801@infradead.org

diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h
index 964442b..2a0b8dd 100644 (file)
--- a/arch/x86/include/asm/paravirt.h
+++ b/arch/x86/include/asm/paravirt.h
@@ -743,6 +743,7 @@ extern void default_banner(void);
         word 771b;                             \
         .byte ptype;                           \
         .byte 772b-771b;                       \
+        _ASM_ALIGN;                            \
        .popsection
 
 

diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h
index 89df6c6..27b036a 100644 (file)
--- a/arch/x86/include/asm/paravirt_types.h
+++ b/arch/x86/include/asm/paravirt_types.h
@@ -294,6 +294,7 @@ extern struct paravirt_patch_template pv_ops;
        "  .byte " type "\n"                            \
        "  .byte 772b-771b\n"                           \
        "  .short " clobber "\n"                        \
+       _ASM_ALIGN "\n"                                 \
        ".popsection\n"
 
 /* Generate patchable code, with the default asm parameters. */