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Commit b4b541a6 authored by Andy Lutomirski's avatar Andy Lutomirski Committed by H. Peter Anvin
Browse files

x86, vdso: Patch alternatives in the 32-bit VDSO 



We need the alternatives mechanism for rdtsc_barrier() to work.

Signed-off-by: default avatarStefani Seibold <stefani@seibold.net>
Link: http://lkml.kernel.org/r/1395094933-14252-9-git-send-email-stefani@seibold.net


Signed-off-by: default avatarH. Peter Anvin <hpa@linux.intel.com>
parent ef721987

arch/x86/include/asm/vdso.h

+2 −0
Original line number Diff line number Diff line
@@ -28,4 +28,6 @@ extern const char vdso32_int80_start, vdso32_int80_end; 
extern const char vdso32_syscall_start, vdso32_syscall_end;

extern const char vdso32_sysenter_start, vdso32_sysenter_end;



void __init patch_vdso32(void *vdso, size_t len);



#endif /* _ASM_X86_VDSO_H */

arch/x86/vdso/Makefile

+2 −1
Original line number Diff line number Diff line
@@ -21,7 +21,8 @@ vobjs-$(VDSOX32-y) += $(vobjx32s-compat) 
vobj64s := $(filter-out $(vobjx32s-compat),$(vobjs-y))



# files to link into kernel

obj-$(VDSO64-y)			+= vma.o vdso.o

obj-y				+= vma.o

obj-$(VDSO64-y)			+= vdso.o

obj-$(VDSOX32-y)		+= vdsox32.o

obj-$(VDSO32-y)			+= vdso32.o vdso32-setup.o

arch/x86/vdso/vdso32-setup.c

+12 −11
Original line number Diff line number Diff line
@@ -112,24 +112,25 @@ void enable_sep_cpu(void) 


int __init sysenter_setup(void)

{

	void *syscall_page = (void *)get_zeroed_page(GFP_ATOMIC);

	const void *vsyscall;

	size_t vsyscall_len;

	void *vdso_page = (void *)get_zeroed_page(GFP_ATOMIC);

	const void *vdso;

	size_t vdso_len;



	vdso32_pages[0] = virt_to_page(syscall_page);

	vdso32_pages[0] = virt_to_page(vdso_page);



	if (vdso32_syscall()) {

		vsyscall = &vdso32_syscall_start;

		vsyscall_len = &vdso32_syscall_end - &vdso32_syscall_start;

		vdso = &vdso32_syscall_start;

		vdso_len = &vdso32_syscall_end - &vdso32_syscall_start;

	} else if (vdso32_sysenter()){

		vsyscall = &vdso32_sysenter_start;

		vsyscall_len = &vdso32_sysenter_end - &vdso32_sysenter_start;

		vdso = &vdso32_sysenter_start;

		vdso_len = &vdso32_sysenter_end - &vdso32_sysenter_start;

	} else {

		vsyscall = &vdso32_int80_start;

		vsyscall_len = &vdso32_int80_end - &vdso32_int80_start;

		vdso = &vdso32_int80_start;

		vdso_len = &vdso32_int80_end - &vdso32_int80_start;

	}



	memcpy(syscall_page, vsyscall, vsyscall_len);

	memcpy(vdso_page, vdso, vdso_len);

	patch_vdso32(vdso_page, vdso_len);



	return 0;

}

arch/x86/vdso/vma.c

+10 −3
Original line number Diff line number Diff line
@@ -16,6 +16,7 @@ 
#include <asm/vdso.h>

#include <asm/page.h>



#if defined(CONFIG_X86_64)

unsigned int __read_mostly vdso_enabled = 1;



extern char vdso_start[], vdso_end[];
@@ -28,8 +29,12 @@ static unsigned vdso_size; 
extern char vdsox32_start[], vdsox32_end[];

extern struct page *vdsox32_pages[];

static unsigned vdsox32_size;

#endif

#endif



static void __init patch_vdsox32(void *vdso, size_t len)

#if defined(CONFIG_X86_32) || defined(CONFIG_X86_X32_ABI) || \

	defined(CONFIG_COMPAT)

void __init patch_vdso32(void *vdso, size_t len)

{

	Elf32_Ehdr *hdr = vdso;

	Elf32_Shdr *sechdrs, *alt_sec = 0;
@@ -52,7 +57,7 @@ static void __init patch_vdsox32(void *vdso, size_t len) 
	}



	/* If we get here, it's probably a bug. */

	pr_warning("patch_vdsox32: .altinstructions not found\n");

	pr_warning("patch_vdso32: .altinstructions not found\n");

	return;  /* nothing to patch */



found:
@@ -61,6 +66,7 @@ static void __init patch_vdsox32(void *vdso, size_t len) 
}

#endif



#if defined(CONFIG_X86_64)

static void __init patch_vdso64(void *vdso, size_t len)

{

	Elf64_Ehdr *hdr = vdso;
@@ -104,7 +110,7 @@ static int __init init_vdso(void) 
		vdso_pages[i] = virt_to_page(vdso_start + i*PAGE_SIZE);



#ifdef CONFIG_X86_X32_ABI

	patch_vdsox32(vdsox32_start, vdsox32_end - vdsox32_start);

	patch_vdso32(vdsox32_start, vdsox32_end - vdsox32_start);

	npages = (vdsox32_end - vdsox32_start + PAGE_SIZE - 1) / PAGE_SIZE;

	vdsox32_size = npages << PAGE_SHIFT;

	for (i = 0; i < npages; i++)
@@ -204,3 +210,4 @@ static __init int vdso_setup(char *s) 
	return 0;

}

__setup("vdso=", vdso_setup);

#endif