x86: use ELF section to list CPU vendor specific code

Replace the hardcoded list of initialization functions for each CPU
vendor by a list in an ELF section, which is read at initialization in
arch/x86/kernel/cpu/cpu.c to fill the cpu_devs[] array. The ELF
section, named .x86cpuvendor.init, is reclaimed after boot, and
contains entries of type "struct cpu_vendor_dev" which associates a
vendor number with a pointer to a "struct cpu_dev" structure.

This first modification allows to remove all the VENDOR_init_cpu()
functions.

This patch also removes the hardcoded calls to early_init_amd() and
early_init_intel(). Instead, we add a "c_early_init" member to the
cpu_dev structure, which is then called if not NULL by the generic CPU
initialization code. Unfortunately, in early_cpu_detect(), this_cpu is
not yet set, so we have to use the cpu_devs[] array directly.

This patch is part of the Linux Tiny project, and is needed for
further patch that will allow to disable compilation of unused CPU
support code.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 13 insertions, 13 deletions

diff --git a/arch/x86/kernel/cpu/cpu.h b/arch/x86/kernel/cpu/cpu.h
index e0b38c33d842..783691b2a738 100644
--- a/arch/x86/kernel/cpu/cpu.h
+++ b/arch/x86/kernel/cpu/cpu.h
@@ -14,6 +14,7 @@ struct cpu_dev {
 
 	struct		cpu_model_info c_models[4];
 
+	void            (*c_early_init)(struct cpuinfo_x86 *c);
 	void		(*c_init)(struct cpuinfo_x86 * c);
 	void		(*c_identify)(struct cpuinfo_x86 * c);
 	unsigned int	(*c_size_cache)(struct cpuinfo_x86 * c, unsigned int size);
@@ -21,18 +22,17 @@ struct cpu_dev {
 
 extern struct cpu_dev * cpu_devs [X86_VENDOR_NUM];
 
+struct cpu_vendor_dev {
+	int vendor;
+	struct cpu_dev *cpu_dev;
+};
+
+#define cpu_vendor_dev_register(cpu_vendor_id, cpu_dev) \
+	static struct cpu_vendor_dev __cpu_vendor_dev_##cpu_vendor_id __used \
+	__attribute__((__section__(".x86cpuvendor.init"))) = \
+	{ cpu_vendor_id, cpu_dev }
+
+extern struct cpu_vendor_dev __x86cpuvendor_start[], __x86cpuvendor_end[];
+
 extern int get_model_name(struct cpuinfo_x86 *c);
 extern void display_cacheinfo(struct cpuinfo_x86 *c);
-
-extern void early_init_intel(struct cpuinfo_x86 *c);
-extern void early_init_amd(struct cpuinfo_x86 *c);
-
-/* Specific CPU type init functions */
-int intel_cpu_init(void);
-int amd_init_cpu(void);
-int cyrix_init_cpu(void);
-int nsc_init_cpu(void);
-int centaur_init_cpu(void);
-int transmeta_init_cpu(void);
-int nexgen_init_cpu(void);
-int umc_init_cpu(void);