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Commit 6a52e4b1 authored by Jeremy Fitzhardinge's avatar Jeremy Fitzhardinge Committed by Ingo Molnar
Browse files

x86_64: further cleanup of 32-bit compat syscall mechanisms 



AMD only supports "syscall" from 32-bit compat usermode.
Intel and Centaur(?) only support "sysenter" from 32-bit compat usermode.

Set the X86 feature bits accordingly, and set up the vdso in
accordance with those bits.  On the offchance we run on in a 64-bit
environment which supports neither syscall nor sysenter from 32-bit
mode, then fall back to the int $0x80 vdso.

Signed-off-by: default avatarJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: default avatarH. Peter Anvin <hpa@zytor.com>
parent 71415c6a

arch/x86/kernel/cpu/amd_64.c

+2 −0
Original line number Diff line number Diff line
@@ -115,6 +115,8 @@ static void __cpuinit early_init_amd(struct cpuinfo_x86 *c) 
	/* c->x86_power is 8000_0007 edx. Bit 8 is constant TSC */

	if (c->x86_power & (1<<8))

		set_cpu_cap(c, X86_FEATURE_CONSTANT_TSC);



	set_cpu_cap(c, X86_FEATURE_SYSCALL32);

}



static void __cpuinit init_amd(struct cpuinfo_x86 *c)

arch/x86/kernel/cpu/common_64.c

+0 −3
Original line number Diff line number Diff line
@@ -317,9 +317,6 @@ static void __cpuinit early_identify_cpu(struct cpuinfo_x86 *c) 
		c->x86_phys_bits = eax & 0xff;

	}



	/* Assume all 64-bit CPUs support 32-bit syscall */

	set_cpu_cap(c, X86_FEATURE_SYSCALL32);



	if (c->x86_vendor != X86_VENDOR_UNKNOWN &&

	    cpu_devs[c->x86_vendor]->c_early_init)

		cpu_devs[c->x86_vendor]->c_early_init(c);

arch/x86/vdso/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -62,7 +62,7 @@ $(obj)/%-syms.lds: $(obj)/%.so.dbg FORCE 
# Build multiple 32-bit vDSO images to choose from at boot time.

#

obj-$(VDSO32-y)			+= vdso32-syms.lds

vdso32.so-$(CONFIG_X86_32)	+= int80

vdso32.so-$(VDSO32-y)		+= int80

vdso32.so-$(CONFIG_COMPAT)	+= syscall

vdso32.so-$(VDSO32-y)		+= sysenter

arch/x86/vdso/vdso32-setup.c

+9 −10
Original line number Diff line number Diff line
@@ -193,17 +193,12 @@ static __init void relocate_vdso(Elf32_Ehdr *ehdr) 
	}

}



/*

 * These symbols are defined by vdso32.S to mark the bounds

 * of the ELF DSO images included therein.

 */

extern const char vdso32_default_start, vdso32_default_end;

extern const char vdso32_sysenter_start, vdso32_sysenter_end;

static struct page *vdso32_pages[1];



#ifdef CONFIG_X86_64



#define	vdso32_sysenter()	(boot_cpu_has(X86_FEATURE_SYSENTER32))

#define	vdso32_syscall()	(boot_cpu_has(X86_FEATURE_SYSCALL32))



/* May not be __init: called during resume */

void syscall32_cpu_init(void)
@@ -226,6 +221,7 @@ static inline void map_compat_vdso(int map) 
#else  /* CONFIG_X86_32 */



#define vdso32_sysenter()	(boot_cpu_has(X86_FEATURE_SEP))

#define vdso32_syscall()	(0)



void enable_sep_cpu(void)

{
@@ -296,12 +292,15 @@ int __init sysenter_setup(void) 
	gate_vma_init();

#endif



	if (!vdso32_sysenter()) {

		vsyscall = &vdso32_default_start;

		vsyscall_len = &vdso32_default_end - &vdso32_default_start;

	} else {

	if (vdso32_syscall()) {

		vsyscall = &vdso32_syscall_start;

		vsyscall_len = &vdso32_syscall_end - &vdso32_syscall_start;

	} else if (vdso32_sysenter()){

		vsyscall = &vdso32_sysenter_start;

		vsyscall_len = &vdso32_sysenter_end - &vdso32_sysenter_start;

	} else {

		vsyscall = &vdso32_int80_start;

		vsyscall_len = &vdso32_int80_end - &vdso32_int80_start;

	}



	memcpy(syscall_page, vsyscall, vsyscall_len);

arch/x86/vdso/vdso32.S

+8 −5
Original line number Diff line number Diff line
@@ -2,14 +2,17 @@ 


__INITDATA



	.globl vdso32_default_start, vdso32_default_end

vdso32_default_start:

#ifdef CONFIG_X86_32

	.globl vdso32_int80_start, vdso32_int80_end

vdso32_int80_start:

	.incbin "arch/x86/vdso/vdso32-int80.so"

#else

vdso32_int80_end:



	.globl vdso32_syscall_start, vdso32_syscall_end

vdso32_syscall_start:

#ifdef CONFIG_COMPAT

	.incbin "arch/x86/vdso/vdso32-syscall.so"

#endif

vdso32_default_end:

vdso32_syscall_end:



	.globl vdso32_sysenter_start, vdso32_sysenter_end

vdso32_sysenter_start: