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Revision 61f01dd941ba9e06d2bf05994450ecc3d61b6b8b authored by Andy Lutomirski on 26 April 2015, 23:47:59 UTC, committed by Linus Torvalds on 27 April 2015, 00:57:38 UTC 
x86_64, asm: Work around AMD SYSRET SS descriptor attribute issue
 
AMD CPUs don't reinitialize the SS descriptor on SYSRET, so SYSRET with
SS == 0 results in an invalid usermode state in which SS is apparently
equal to __USER_DS but causes #SS if used.

Work around the issue by setting SS to __KERNEL_DS __switch_to, thus
ensuring that SYSRET never happens with SS set to NULL.

This was exposed by a recent vDSO cleanup.

Fixes: e7d6eefaaa44 x86/vdso32/syscall.S: Do not load __USER32_DS to %ss
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Peter Anvin <hpa@zytor.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Denys Vlasenko <vda.linux@googlemail.com>
Cc: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent 1190944
Raw File
decompress_v32.lds 
/*#OUTPUT_FORMAT(elf32-us-cris) */
OUTPUT_ARCH (crisv32)

MEMORY
	{
	dram : ORIGIN = 0x40700000,
	       LENGTH = 0x00100000
	}

SECTIONS
{
	.text :
	{
		_stext = . ;
		*(.text)
		*(.rodata)
		*(.rodata.*)
		_etext = . ;
	} > dram
	.data :
	{
		*(.data)
		_edata = . ;
	} > dram
	.bss :
	{
		*(.bss)
		_end = ALIGN( 0x10 ) ;
	} > dram
}
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