From: Roland McGrath Date: Fri, 7 Mar 2008 22:56:02 +0000 (-0800) Subject: x86_64: make ptrace always sign-extend orig_ax to 64 bits X-Git-Tag: v2.6.25-rc5~7 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=84c6f6046c5a2189160a8f0dca8b90427bf690ea;p=pandora-kernel.git x86_64: make ptrace always sign-extend orig_ax to 64 bits This makes 64-bit ptrace calls setting the 64-bit orig_ax field for a 32-bit task sign-extend the low 32 bits up to 64. This matches what a 64-bit debugger expects when tracing a 32-bit task. This follows on my "x86_64 ia32 syscall restart fix". This didn't matter until that was fixed. The debugger ignores or zeros the high half of every register slot it sets (including the orig_rax pseudo-register) uniformly. It expects that the setting of the low 32 bits always has the same meaning as a 32-bit debugger setting those same 32 bits with native 32-bit facilities. This never arose before because the syscall restart check never matched any -ERESTART* values due to lack of sign extension. Before that fix, even 32-bit ptrace setting orig_eax to -1 failed to trigger the restart check anyway. So this was never noticed as a regression of 64-bit debuggers vs 32-bit debuggers on the same 64-bit kernel. Signed-off-by: Roland McGrath [ Changed to just do the sign-extension unconditionally on x86-64, since orig_ax is always just a small integer and doesn't need the full 64-bit range ] Signed-off-by: Linus Torvalds --- Reading git-diff-tree failed