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x86/entry/64/compat: Set up full pt_regs for all compat syscalls

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This is conceptually simpler.  More importantly, it eliminates
the PTREGSCALL and execve stubs, which were not compatible with
the C ABI.  This means that C code can call through the compat
syscall table.

The execve stubs are a bit subtle.  They did two things: they
cleared some registers and they forced slow-path return.
Neither is necessary any more: elf_common_init clears the extra
registers and start_thread calls force_iret().

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/f95b7f7dfaacf88a8cae85bb06226cae53769287.1444091584.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Andy Lutomirski
2015-10-05 17:48:05 -07:00
committed by Ingo Molnar
parent 2ec67971fa
commit 8169aff611
3 changed files with 20 additions and 40 deletions
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6
arch/x86/entry/entry_64.S
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@@ -391,20 +391,16 @@ GLOBAL(stub_execveat)
jmp return_from_execve
END(stub_execveat)
#if defined(CONFIG_X86_X32_ABI) || defined(CONFIG_IA32_EMULATION)
#if defined(CONFIG_X86_X32_ABI)
.align 8
GLOBAL(stub_x32_execve)
GLOBAL(stub32_execve)
call compat_sys_execve
jmp return_from_execve
END(stub32_execve)
END(stub_x32_execve)
.align 8
GLOBAL(stub_x32_execveat)
GLOBAL(stub32_execveat)
call compat_sys_execveat
jmp return_from_execve
END(stub32_execveat)
END(stub_x32_execveat)
#endif