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Subject[PATCH v2 3/5] x86/boot: Defer setup_real_mode() to early_initcall time
Date
There's no need to run setup_real_mode() as early as we run it.
Defer it to the same early_initcall that sets up the page
permissions for the real mode code.

This should be a code size reduction. More importantly, it give us
a longer window in which we can allocate the real mode trampoline.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
---
arch/x86/include/asm/realmode.h | 1 -
arch/x86/kernel/setup.c | 2 --
arch/x86/realmode/init.c | 15 ++++++++++++---
3 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/arch/x86/include/asm/realmode.h b/arch/x86/include/asm/realmode.h
index 9c6b890d5e7a..8d6777724ba4 100644
--- a/arch/x86/include/asm/realmode.h
+++ b/arch/x86/include/asm/realmode.h
@@ -59,6 +59,5 @@ extern unsigned char secondary_startup_64[];
#endif

void reserve_real_mode(void);
-void setup_real_mode(void);

#endif /* _ARCH_X86_REALMODE_H */
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 47006b28cac4..c39a4a28fea1 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -1137,8 +1137,6 @@ void __init setup_arch(char **cmdline_p)
/* A CPU has %cr4 if and only if it has CPUID. */
mmu_cr4_features = __read_cr4();

- setup_real_mode();
-
memblock_set_current_limit(get_max_mapped());

/*
diff --git a/arch/x86/realmode/init.c b/arch/x86/realmode/init.c
index c5bdc4e473e7..747b71e8f547 100644
--- a/arch/x86/realmode/init.c
+++ b/arch/x86/realmode/init.c
@@ -30,7 +30,7 @@ void __init reserve_real_mode(void)
base, (unsigned long long)mem, size);
}

-void __init setup_real_mode(void)
+static void __init setup_real_mode(void)
{
u16 real_mode_seg;
const u32 *rel;
@@ -101,7 +101,7 @@ void __init setup_real_mode(void)
* need to mark it executable at do_pre_smp_initcalls() at least,
* thus run it as a early_initcall().
*/
-static int __init set_real_mode_permissions(void)
+static void __init set_real_mode_permissions(void)
{
unsigned char *base = (unsigned char *) real_mode_header;
size_t size = PAGE_ALIGN(real_mode_blob_end - real_mode_blob);
@@ -120,7 +120,16 @@ static int __init set_real_mode_permissions(void)
set_memory_nx((unsigned long) base, size >> PAGE_SHIFT);
set_memory_ro((unsigned long) base, ro_size >> PAGE_SHIFT);
set_memory_x((unsigned long) text_start, text_size >> PAGE_SHIFT);
+}
+
+static int __init init_real_mode(void)
+{
+ if (!real_mode_header)
+ panic("Real mode trampoline was not allocated");
+
+ setup_real_mode();
+ set_real_mode_permissions();

return 0;
}
-early_initcall(set_real_mode_permissions);
+early_initcall(init_real_mode);
--
2.7.4
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