linux-kernel - [RFC v2 3/6] x86/init: move ebda reservations into linker table

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Date:	Fri, 19 Feb 2016 06:15:40 -0800
From:	"Luis R. Rodriguez" <mcgrof@...nel.org>
To:	hpa@...or.com, tglx@...utronix.de, mingo@...hat.com, bp@...en8.de
Cc:	x86@...nel.org, linux-kernel@...r.kernel.org, luto@...capital.net,
	boris.ostrovsky@...cle.com, rusty@...tcorp.com.au,
	david.vrabel@...rix.com, konrad.wilk@...cle.com, mcb30@...e.org,
	jgross@...e.com, andriy.shevchenko@...ux.intel.com,
	xen-devel@...ts.xensource.com,
	"Luis R. Rodriguez" <mcgrof@...nel.org>
Subject: [RFC v2 3/6] x86/init: move ebda reservations into linker table

This lets us annotate its requirements specifically for
PC and lguest subarchitectures. While at it since head.c
just has ebda data rename it. Since we're using linker tables
and both x86 32-bit and 64-bit have them we don't need
to declare a call for this separately. This lets us
also keep this declared static now.

Since we're using linker tables and have support to annotate
subarchitecture do that instead. pv_legacy() is incorrect as
its really only for legacy PV guests. There's no need for
pv_legacy() check anymore now.

v2:

- Fix 0-day bot testing of on linking now rebranded
  head.o as ebda.o
- Since we dropped paravirt_enabled() --> paravirt_legacy()
  rename in favor of just removing paravirt_enabled() this
  is based on that assumption. This removes one use case.

Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Signed-off-by: Luis R. Rodriguez <mcgrof@...nel.org>
---
 arch/x86/Makefile                  | 1 -
 arch/x86/include/asm/bios_ebda.h   | 2 --
 arch/x86/kernel/Makefile           | 3 ++-
 arch/x86/kernel/{head.c => ebda.c} | 6 +++---
 arch/x86/kernel/head32.c           | 2 --
 arch/x86/kernel/head64.c           | 2 --
 6 files changed, 5 insertions(+), 11 deletions(-)
 rename arch/x86/kernel/{head.c => ebda.c} (94%)

diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index 4086abca0b32..ec9a798ffe6c 100644
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -208,7 +208,6 @@ endif
 
 head-y := arch/x86/kernel/head_$(BITS).o
 head-y += arch/x86/kernel/head$(BITS).o
-head-y += arch/x86/kernel/head.o
 
 libs-y  += arch/x86/lib/
 
diff --git a/arch/x86/include/asm/bios_ebda.h b/arch/x86/include/asm/bios_ebda.h
index aa6a3170ab5a..e63347eb3804 100644
--- a/arch/x86/include/asm/bios_ebda.h
+++ b/arch/x86/include/asm/bios_ebda.h
@@ -38,8 +38,6 @@ static inline unsigned int get_bios_ebda_length(void)
 	return length;
 }
 
-void reserve_ebda_region(void);
-
 #ifdef CONFIG_X86_CHECK_BIOS_CORRUPTION
 /*
  * This is obviously not a great place for this, but we want to be
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index be167a0a5e2c..f5b3de07142b 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -2,7 +2,7 @@
 # Makefile for the linux kernel.
 #
 
-extra-y                := head_$(BITS).o head$(BITS).o head.o vmlinux.lds
+extra-y                := head_$(BITS).o head$(BITS).o vmlinux.lds
 
 CPPFLAGS_vmlinux.lds += -U$(UTS_MACHINE)
 
@@ -22,6 +22,7 @@ KASAN_SANITIZE_dumpstack_$(BITS).o := n
 
 CFLAGS_irq.o := -I$(src)/../include/asm/trace
 
+obj-y			:= ebda.o
 obj-y			:= process_$(BITS).o signal.o
 obj-y			+= init.o sort-init.o
 obj-$(CONFIG_X86_DEBUG_LINKER_TABLES) += dbg-tables/
diff --git a/arch/x86/kernel/head.c b/arch/x86/kernel/ebda.c
similarity index 94%
rename from arch/x86/kernel/head.c
rename to arch/x86/kernel/ebda.c
index 4e3be58a1a77..defc2f07a80b 100644
--- a/arch/x86/kernel/head.c
+++ b/arch/x86/kernel/ebda.c
@@ -4,6 +4,7 @@
 
 #include <asm/setup.h>
 #include <asm/bios_ebda.h>
+#include <asm/x86_init.h>
 
 /*
  * The BIOS places the EBDA/XBDA at the top of conventional
@@ -26,7 +27,7 @@
 #define LOWMEM_CAP		0x9f000U	/* Absolute maximum */
 #define INSANE_CUTOFF		0x20000U	/* Less than this = insane */
 
-void __init reserve_ebda_region(void)
+static void __init reserve_ebda_region(void)
 {
 	unsigned int lowmem, ebda_addr;
 
@@ -38,8 +39,6 @@ void __init reserve_ebda_region(void)
 	 * that the paravirt case can handle memory setup
 	 * correctly, without our help.
 	 */
-	if (boot_params.hdr.hardware_subarch != X86_SUBARCH_PC)
-		return;
 
 	/* end of low (conventional) memory */
 	lowmem = *(unsigned short *)__va(BIOS_LOWMEM_KILOBYTES);
@@ -69,3 +68,4 @@ void __init reserve_ebda_region(void)
 	/* reserve all memory between lowmem and the 1MB mark */
 	memblock_reserve(lowmem, 0x100000 - lowmem);
 }
+x86_init_early_pc_simple(reserve_ebda_region);
diff --git a/arch/x86/kernel/head32.c b/arch/x86/kernel/head32.c
index d93f3e42e61b..768fa3888066 100644
--- a/arch/x86/kernel/head32.c
+++ b/arch/x86/kernel/head32.c
@@ -26,8 +26,6 @@ static void __init i386_default_early_setup(void)
 	/* Initialize 32bit specific setup functions */
 	x86_init.resources.reserve_resources = i386_reserve_resources;
 	x86_init.mpparse.setup_ioapic_ids = setup_ioapic_ids_from_mpc;
-
-	reserve_ebda_region();
 }
 
 asmlinkage __visible void __init i386_start_kernel(void)
diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index a3b56aecaeda..a823447139f5 100644
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c
@@ -194,8 +194,6 @@ void __init x86_64_start_reservations(char *real_mode_data)
 	x86_init_fn_init_tables();
 	x86_init_fn_early_init();
 
-	reserve_ebda_region();
-
 	switch (boot_params.hdr.hardware_subarch) {
 	case X86_SUBARCH_INTEL_MID:
 		x86_intel_mid_early_setup();
-- 
2.7.0