Messages in this thread | | | Date | Wed, 23 Sep 2009 17:41:18 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH 0/4] x86: clean up orig_ax handling |
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* Roland McGrath <roland@redhat.com> wrote:
> Here is the aforementioned other tack on this. > > I said earlier that getreg() (i.e. 64-bit ptrace/core-dump fetches) > should sign-extend the low 32 bits of orig_ax up. But I've changed my > mind. It's true that today you can store 0xffffffff via either 64-bit > ptrace or 32-bit ptrace and then read back -1 via 64-bit ptrace. (This > wasn't always so, and so we can hope that no debugger really depends on > it.) What seems more important is that tracing and core dumps correctly > show the full orig_ax value incoming in %rax from userland, since > %rax=__NR_foo|(1UL<<32) behaves differently (i.e. -ENOSYS) than > %eax=_NR_foo in actual fact when user-mode does "syscall" with those > values. In a bogon case like that, you would like to have traces/dumps > tell you why the task is not making a proper syscall rather than lie > about what register bits it entered the kernel with. > > Patches 1-3 change no ptrace-tests outcomes, i.e. don't regress on the > test cases that went with the original sign-extension changes. They > reintroduce e.g. the ability to blindly read and write back the whole > regset when at syscall-entry tracing with %rax=__NR_foo|(1UL<<32) and > have that fail with -ENOSYS as it would without tracing rather than > perturb the tracee to call sys_foo instead. (Not that this is useful.) > > Patch 4 does Linus's fix for the outstanding bug. I've verified it works. > > > Thanks, > Roland > --- > The following changes since commit 7fa07729e439a6184bd824746d06a49cca553f15: > Linus Torvalds (1): > Merge branch 'perf-fixes-for-linus' of git://git.kernel.org/.../tip/linux-2.6-tip > > are available in the git repository at: > > git://git.kernel.org/pub/scm/linux/kernel/git/frob/linux-2.6-roland.git x86/orig_ax > > Roland McGrath (4): > asm-generic: syscall_get_nr returns int > x86: syscall_get_nr returns int > x86: ptrace: do not sign-extend orig_ax on write > x86: ptrace: set TS_COMPAT when 32-bit ptrace sets orig_eax>=0 > > arch/x86/include/asm/syscall.h | 14 +++++++------- > arch/x86/kernel/ptrace.c | 21 ++++++++------------- > include/asm-generic/syscall.h | 8 ++++++-- > 3 files changed, 21 insertions(+), 22 deletions(-)
Linus, this series looks good to me. Do you want to pull this directly or should we test this for a few days in the x86 tree? (either solution is fine to me)
Ingo
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