Re: [uml-devel] [PATCH] um: v3: Fix FP register size for XSTATE/XSAVE

[Thomas Meyer]

Am 10.07.2017 9:06 nachm. schrieb Richard Weinberger <rich...@nod.at>:

Thomas,

Am 10.07.2017 um 00:33 schrieb Thomas Meyer:
> Hard code max size. Taken from
> https://sourceware.org/git/?p=binutils-gdb.git;a=blob;f=gdb/common/x86-xstate.h
>
> v3: use static fp_regs for get_skas_faultinfo
>
> Signed-off-by: Thomas Meyer <tho...@m3y3r.de>
> ---
>  arch/um/os-Linux/skas/process.c  |  7 ++++---
>  arch/x86/um/os-Linux/registers.c | 18 ++++++++++++------
>  arch/x86/um/user-offsets.c       |  2 +-
>  3 files changed, 17 insertions(+), 10 deletions(-)
>
> diff --git a/arch/um/os-Linux/skas/process.c b/arch/um/os-Linux/skas/process.c
> index 03b3c4cc7735..b5fdef795985 100644
> --- a/arch/um/os-Linux/skas/process.c
> +++ b/arch/um/os-Linux/skas/process.c
> @@ -88,12 +88,13 @@ void wait_stub_done(int pid)
> 
>  extern unsigned long current_stub_stack(void);
> 
> +static unsigned long skas_faultinfo_fpregs[FP_SIZE];
> +

Uhmm, are you sure that this does not race with other userspace() instances?

Oh, is it really possible that a task gets schedule while we are in userspace signal handling from ptrace?

Another question: when malloc a memory area in userspace: when does a userspace process end in userspace function!? Where would you free the malloced memory?

Thanks,
//richard

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