The reason for copying of %r8 to %rcx is quite non-obvious.
Add a comment which explains why it is done.
Fix indentation and trailing whitespace while at it.
Signed-off-by: Denys Vlasenko <dvlas...@redhat.com>
CC: Linus Torvalds <torva...@linux-foundation.org>
CC: Steven Rostedt <rost...@goodmis.org>
CC: Ingo Molnar <mi...@kernel.org>
CC: Borislav Petkov <b...@alien8.de>
CC: "H. Peter Anvin" <h...@zytor.com>
CC: Andy Lutomirski <l...@amacapital.net>
CC: Oleg Nesterov <o...@redhat.com>
CC: Frederic Weisbecker <fweis...@gmail.com>
CC: Alexei Starovoitov <a...@plumgrid.com>
CC: Will Drewry <w...@chromium.org>
CC: Kees Cook <keesc...@chromium.org>
CC: x...@kernel.org
CC: linux-kernel@vger.kernel.org
---
This is a resend.
arch/x86/ia32/ia32entry.S | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/arch/x86/ia32/ia32entry.S b/arch/x86/ia32/ia32entry.S
index 2ca052e..8e72256 100644
--- a/arch/x86/ia32/ia32entry.S
+++ b/arch/x86/ia32/ia32entry.S
@@ -562,9 +562,17 @@ GLOBAL(\label)
ALIGN
GLOBAL(stub32_clone)
- leaq sys_clone(%rip),%rax
+ leaq sys_clone(%rip), %rax
+ /*
+ * 32-bit clone API is clone(..., int tls_val, int *child_tidptr).
+ * 64-bit clone API is clone(..., int *child_tidptr, int tls_val).
+ * Native 64-bit kernel's sys_clone() implements the latter.
+ * We need to swap args here. But since tls_val is in fact ignored
+ * by sys_clone(), we can get away with an assignment
+ * (arg4 = arg5) instead of a full swap:
+ */
mov %r8, %rcx
- jmp ia32_ptregs_common
+ jmp ia32_ptregs_common
ALIGN
ia32_ptregs_common:
--
1.8.1.4
--
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