On 06/03/2016 12:57 PM, Cyrill Gorcunov wrote:
On Wed, Jun 01, 2016 at 04:11:36PM +0300, Dmitry Safonov wrote:As the task isn't executing at the moment of {GET,SET}REGS, return regset that corresponds to code selector, rather than value of TIF_IA32 flag. I.e. if we ptrace i386 elf binary that has just changed it's code selector to __USER_CS, than GET_REGS will return full x86_64 register set.Note, that this will work only if application has changed it's CS. If the application does 32-bit syscall with __USER_CS, ptrace will still return 64-bit register set. Which might be still confusing for tools that expect TS_COMPACT to be exposed [1, 2]. So this this change should make PTRACE_GETREGSET more reliable and this will be another step to drop TIF_{IA32,X32} flags. [1]: https://sourceforge.net/p/strace/mailman/message/30471411/ [2]: https://lkml.org/lkml/2012/1/18/320 Cc: Andy Lutomirski <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: "H. Peter Anvin" <[email protected]> Cc: Oleg Nesterov <[email protected]> Signed-off-by: Dmitry Safonov <[email protected]>Looks reasonable! Still if cs has been changed to non-compat selector and we now return 64bit registers set, won't it cause problems for old tools? I suspect it should not but still.
Thanks! Hmm, strace works fine - I'll check gdb to be sure. What else could be bothered by this?
