* Josh Poimboeuf <jpoimboe@xxxxxxxxxx> wrote: > On Wed, May 08, 2019 at 09:49:05AM +0200, Peter Zijlstra wrote: > > Currently pt_regs on x86_32 has an oddity in that kernel regs > > (!user_mode(regs)) are short two entries (esp/ss). This means that any > > code trying to use them (typically: regs->sp) needs to jump through > > some unfortunate hoops. > > > > Change the entry code to fix this up and create a full pt_regs frame. > > > > This then simplifies: > > > > - ftrace > > - kprobes > > - stack unwinder > > - ptrace > > - kdump > > - kgdb > > > > Hated-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> > > Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> > > --- > > arch/x86/entry/entry_32.S | 105 ++++++++++++++++++++++++++++++++++---- > > arch/x86/include/asm/kexec.h | 17 ------ > > arch/x86/include/asm/ptrace.h | 17 ------ > > arch/x86/include/asm/stacktrace.h | 2 > > arch/x86/kernel/crash.c | 8 -- > > arch/x86/kernel/ftrace_32.S | 81 ++++++++++++++++------------- > > arch/x86/kernel/kgdb.c | 8 -- > > arch/x86/kernel/kprobes/common.h | 4 - > > arch/x86/kernel/kprobes/core.c | 29 ++++------ > > arch/x86/kernel/kprobes/opt.c | 20 ++++--- > > arch/x86/kernel/process_32.c | 16 +---- > > arch/x86/kernel/ptrace.c | 29 ---------- > > arch/x86/kernel/time.c | 3 - > > arch/x86/kernel/unwind_frame.c | 32 +---------- > > arch/x86/kernel/unwind_orc.c | 2 > > 15 files changed, 181 insertions(+), 192 deletions(-) > > Very nice diffstat. This moves all the pain to the 32-bit entry code > where it belongs. Yes, that's very convincing and looks like a nice simplification of 32-bit x86 entry concepts overall. Assuming it's correct, the question is whether Linus still hates it? :-) Thanks, Ingo
