x86/fsgsbase/64: Fix ptrace() to read the FS/GS base accurately
On 64-bit kernels ptrace can read the FS/GS base using the register access APIs (PTRACE_PEEKUSER, etc.) or PTRACE_ARCH_PRCTL. Make both of these mechanisms return the actual FS/GS base. This will improve debuggability by providing the correct information to ptracer such as GDB. [ chang: Rebased and revised patch description. ] [ mingo: Revised the changelog some more. ] Signed-off-by:Andy Lutomirski <luto@kernel.org> Signed-off-by:
Chang S. Bae <chang.seok.bae@intel.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Markus T Metzger <markus.t.metzger@intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ravi Shankar <ravi.v.shankar@intel.com> Cc: Rik van Riel <riel@surriel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1537312139-5580-2-git-send-email-chang.seok.bae@intel.com Signed-off-by:
Ingo Molnar <mingo@kernel.org>
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