[Xen-devel] [PATCH] x86/alt: Fix build when CONFIG_LIVEPATCH is disabled

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

c/s b28cd21c3628 "x86/build: Use new .nops directive when available"
introduced a __read_mostly boolean which is included if the toolchain supports
the .nops directive.

When CONFIG_LIVEPATCH is compiled out, alternative.o is expected to be a fully
init module, and toolchain_nops_are_ideal trips the build system check:

  Error: size of alternative.o:.data.read_mostly is 0x01
  /local/xen.git/xen/Rules.mk:206: recipe for target 'alternative.init.o' failed
  make[3]: *** [alternative.init.o] Error 12

Introduce init_or_livepatch_read_mostly and switch the annotation for
toolchain_nops_are_ideal.

Reported-by: Olaf Hering <olaf@xxxxxxxxx>
Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Wei Liu <wei.liu2@xxxxxxxxxx>
CC: Roger Pau Monné <roger.pau@xxxxxxxxxx>
CC: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
CC: Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>
---
 xen/arch/x86/alternative.c  | 2 +-
 xen/include/xen/livepatch.h | 2 ++
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/xen/arch/x86/alternative.c b/xen/arch/x86/alternative.c
index ea835d9..1ae4923 100644
--- a/xen/arch/x86/alternative.c
+++ b/xen/arch/x86/alternative.c
@@ -91,7 +91,7 @@ asm ( ".pushsection .init.rodata, \"a\", @progbits\n\t"
       "toolchain_nops: .nops " __stringify(ASM_NOP_MAX) "\n\t"
       ".popsection\n\t");
 extern char toolchain_nops[ASM_NOP_MAX];
-static bool __read_mostly toolchain_nops_are_ideal;
+static bool init_or_livepatch_read_mostly toolchain_nops_are_ideal;
 
 #else
 # define toolchain_nops_are_ideal false
diff --git a/xen/include/xen/livepatch.h b/xen/include/xen/livepatch.h
index 98ec012..1b1817c 100644
--- a/xen/include/xen/livepatch.h
+++ b/xen/include/xen/livepatch.h
@@ -23,6 +23,7 @@ struct xen_sysctl_livepatch_op;
 #define init_or_livepatch_const
 #define init_or_livepatch_constrel
 #define init_or_livepatch_data
+#define init_or_livepatch_read_mostly __read_mostly
 #define init_or_livepatch
 
 /* Convenience define for printk. */
@@ -121,6 +122,7 @@ void arch_livepatch_unmask(void);
 #define init_or_livepatch_const       __initconst
 #define init_or_livepatch_constrel    __initconstrel
 #define init_or_livepatch_data        __initdata
+#define init_or_livepatch_read_mostly __initdata
 #define init_or_livepatch             __init
 
 static inline int livepatch_op(struct xen_sysctl_livepatch_op *op)
-- 
2.1.4


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