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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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a4780adeef
Since commit 6a1c53124a the user writeable TLS register was zeroed to
prevent it from being used as a covert channel between two tasks.
There are more and more applications coming to Windows RT,
Wine could support them, but mostly they expect to have
the thread environment block (TEB) in TPIDRURW.
This patch preserves that register per thread instead of clearing it.
Unlike the TPIDRURO, which is already switched, the TPIDRURW
can be updated from userspace so needs careful treatment in the case that we
modify TPIDRURW and call fork(). To avoid this we must always read
TPIDRURW in copy_thread.
Signed-off-by: André Hentschel <nerv@dawncrow.de>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Jonathan Austin <jonathan.austin@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
64 lines
1.7 KiB
C
64 lines
1.7 KiB
C
#ifndef __ASMARM_TLS_H
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#define __ASMARM_TLS_H
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#ifdef __ASSEMBLY__
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#include <asm/asm-offsets.h>
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.macro switch_tls_none, base, tp, tpuser, tmp1, tmp2
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.endm
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.macro switch_tls_v6k, base, tp, tpuser, tmp1, tmp2
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mrc p15, 0, \tmp2, c13, c0, 2 @ get the user r/w register
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mcr p15, 0, \tp, c13, c0, 3 @ set TLS register
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mcr p15, 0, \tpuser, c13, c0, 2 @ and the user r/w register
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str \tmp2, [\base, #TI_TP_VALUE + 4] @ save it
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.endm
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.macro switch_tls_v6, base, tp, tpuser, tmp1, tmp2
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ldr \tmp1, =elf_hwcap
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ldr \tmp1, [\tmp1, #0]
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mov \tmp2, #0xffff0fff
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tst \tmp1, #HWCAP_TLS @ hardware TLS available?
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streq \tp, [\tmp2, #-15] @ set TLS value at 0xffff0ff0
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mrcne p15, 0, \tmp2, c13, c0, 2 @ get the user r/w register
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mcrne p15, 0, \tp, c13, c0, 3 @ yes, set TLS register
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mcrne p15, 0, \tpuser, c13, c0, 2 @ set user r/w register
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strne \tmp2, [\base, #TI_TP_VALUE + 4] @ save it
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.endm
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.macro switch_tls_software, base, tp, tpuser, tmp1, tmp2
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mov \tmp1, #0xffff0fff
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str \tp, [\tmp1, #-15] @ set TLS value at 0xffff0ff0
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.endm
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#endif
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#ifdef CONFIG_TLS_REG_EMUL
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#define tls_emu 1
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#define has_tls_reg 1
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#define switch_tls switch_tls_none
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#elif defined(CONFIG_CPU_V6)
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#define tls_emu 0
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#define has_tls_reg (elf_hwcap & HWCAP_TLS)
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#define switch_tls switch_tls_v6
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#elif defined(CONFIG_CPU_32v6K)
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#define tls_emu 0
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#define has_tls_reg 1
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#define switch_tls switch_tls_v6k
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#else
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#define tls_emu 0
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#define has_tls_reg 0
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#define switch_tls switch_tls_software
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#endif
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#ifndef __ASSEMBLY__
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static inline unsigned long get_tpuser(void)
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{
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unsigned long reg = 0;
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if (has_tls_reg && !tls_emu)
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__asm__("mrc p15, 0, %0, c13, c0, 2" : "=r" (reg));
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return reg;
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}
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#endif
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#endif /* __ASMARM_TLS_H */
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