um: Rely on PTRACE_SETREGSET to set FS/GS base registers

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These registers are saved/restored together with the other general
registers using ptrace. In arch_set_tls we then just need to set the
register and it will be synced back normally.

Most of this logic was introduced in commit f355559cf7 ("[PATCH] uml:
x86_64 thread fixes"). However, at least today we can rely on ptrace to
restore the base registers for us. As such, only the part of the patch
that tracks the FS register for use as thread local storage is actually
needed.

Signed-off-by: Benjamin Berg <benjamin@sipsolutions.net>
Signed-off-by: Richard Weinberger <richard@nod.at>

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This commit is contained in:

Benjamin Berg 2023-11-10 12:03:46 +01:00 • committed by Richard Weinberger

parent 21822553a5

commit 1ca1443570

7 changed files with 16 additions and 71 deletions

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3

arch/um/include/shared/os.h

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4

arch/x86/um/asm/elf.h

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3

arch/x86/um/asm/processor_64.h

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1

arch/x86/um/os-Linux/Makefile

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12

arch/x86/um/os-Linux/prctl.c

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62

arch/x86/um/syscalls_64.c

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2

arch/x86/um/tls_64.c

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