kernel.git/arch/tile/mm/fault.c, branch linux-3.2.y

vm: add VM_FAULT_SIGSEGV handling support

2015-02-20T00:49:40Z

commit 33692f27597fcab536d7cbbcc8f52905133e4aa7 upstream. The core VM already knows about VM_FAULT_SIGBUS, but cannot return a "you should SIGSEGV" error, because the SIGSEGV case was generally handled by the caller - usually the architecture fault handler. That results in lots of duplication - all the architecture fault handlers end up doing very similar "look up vma, check permissions, do retries etc" - but it generally works. However, there are cases where the VM actually wants to SIGSEGV, and applications _expect_ SIGSEGV. In particular, when accessing the stack guard page, libsigsegv expects a SIGSEGV. And it usually got one, because the stack growth is handled by that duplicated architecture fault handler. However, when the generic VM layer started propagating the error return from the stack expansion in commit fee7e49d4514 ("mm: propagate error from stack expansion even for guard page"), that now exposed the existing VM_FAULT_SIGBUS result to user space. And user space really expected SIGSEGV, not SIGBUS. To fix that case, we need to add a VM_FAULT_SIGSEGV, and teach all those duplicate architecture fault handlers about it. They all already have the code to handle SIGSEGV, so it's about just tying that new return value to the existing code, but it's all a bit annoying. This is the mindless minimal patch to do this. A more extensive patch would be to try to gather up the mostly shared fault handling logic into one generic helper routine, and long-term we really should do that cleanup. Just from this patch, you can generally see that most architectures just copied (directly or indirectly) the old x86 way of doing things, but in the meantime that original x86 model has been improved to hold the VM semaphore for shorter times etc and to handle VM_FAULT_RETRY and other "newer" things, so it would be a good idea to bring all those improvements to the generic case and teach other architectures about them too. Reported-and-tested-by: Takashi Iwai Tested-by: Jan Engelhardt Acked-by: Heiko Carstens # "s390 still compiles and boots" Cc: linux-arch@vger.kernel.org Signed-off-by: Linus Torvalds [bwh: Backported to 3.2: - Adjust filenames, context - Drop arc, metag, nios2 and lustre changes - For sh, patch both 32-bit and 64-bit implementations to use goto bad_area - For s390, pass int_code and trans_exc_code as arguments to do_no_context() and do_sigsegv()] Signed-off-by: Ben Hutchings

arch/tile: support signal "exception-trace" hook

2011-05-20T02:55:59Z

This change adds support for /proc/sys/debug/exception-trace to tile. Like x86 and sparc, by default it is set to "1", generating a one-line printk whenever a user process crashes. By setting it to "2", we get a much more complete userspace diagnostic at crash time, including a user-space backtrace, register dump, and memory dump around the address of the crash. Some vestiges of the Tilera-internal version of this support are removed with this patch (the show_crashinfo variable and the arch_coredump_signal function). We retain a "crashinfo" boot parameter which allows you to set the boot-time value of exception-trace. Signed-off-by: Chris Metcalf

arch/tile: support TIF_NOTIFY_RESUME

2011-05-02T22:53:35Z

This support is required for CONFIG_KEYS, NFSv4 kernel DNS, etc. The change is slightly more complex than the minimal thing, since I took advantage of having to go into the assembly code to just move a bunch of stuff into C code: specifically, the schedule(), do_async_page_fault(), do_signal(), and single_step_once() support, in addition to the TIF_NOTIFY_RESUME support. Signed-off-by: Chris Metcalf

Fix common misspellings

2011-03-31T14:26:23Z

Fixes generated by 'codespell' and manually reviewed. Signed-off-by: Lucas De Marchi

arch/tile: fix some comments and whitespace

2011-03-10T18:14:03Z

This is a grab bag of changes with no actual change to generated code. This includes whitespace and comment typos, plus a couple of stale comments being removed. Signed-off-by: Chris Metcalf

BKL: remove extraneous #include

2010-11-17T16:59:32Z

The big kernel lock has been removed from all these files at some point, leaving only the #include. Remove this too as a cleanup. Signed-off-by: Arnd Bergmann Signed-off-by: Linus Torvalds

arch/tile: parameterize system PLs to support KVM port

2010-10-15T19:38:09Z

While not a port to KVM (yet), this change modifies the kernel to be able to build either at PL1 or at PL2 with a suitable config switch. Pushing up this change avoids handling branch merge issues going forward with the KVM work. Signed-off-by: Chris Metcalf

arch/tile: Use

2010-10-14T18:34:33Z

With this change we now include into the "tile" version of the header. To take full advantage of the prototypes there, we also change our naming convention for "struct pt_regs *" syscalls so that, e.g., _sys_execve() is the "true" syscall entry, which sets the appropriate register to point to the pt_regs before calling sys_execve(). While doing this I realized I no longer needed the fork and vfork entry point stubs, since those functions aren't in the generic syscall ABI, so I removed them as well. Signed-off-by: Chris Metcalf

arch/tile: Various cleanups.

2010-08-13T12:52:19Z

This change rolls up random cleanups not representing any actual bugs. - Remove a stale CONFIG_ value from the default tile_defconfig - Remove unused tns_atomic_xxx() family of methods from - Optimize get_order() using Tile's "clz" instruction - Fix a bad hypervisor upcall name (not currently used in Linux anyway) - Use __copy_in_user_inatomic() name for consistency, and export it - Export some additional hypervisor driver I/O upcalls and some homecache calls - Remove the obfuscating MEMCPY_TEST_WH64 support code - Other stray comment cleanups, #if 0 removal, etc. Signed-off-by: Chris Metcalf

arch/tile: Miscellaneous cleanup changes.

2010-07-06T17:41:51Z

This commit is primarily changes caused by reviewing "sparse" and "checkpatch" output on our sources, so is somewhat noisy, since things like "printk() -> pr_err()" (or whatever) throughout the codebase tend to get tedious to read. Rather than trying to tease apart precisely which things changed due to which type of code review, this commit includes various cleanups in the code: - sparse: Add declarations in headers for globals. - sparse: Fix __user annotations. - sparse: Using gfp_t consistently instead of int. - sparse: removing functions not actually used. - checkpatch: Clean up printk() warnings by using pr_info(), etc.; also avoid partial-line printks except in bootup code. - checkpatch: Use exposed structs rather than typedefs. - checkpatch: Change some C99 comments to C89 comments. In addition, a couple of minor other changes are rolled in to this commit: - Add support for a "raise" instruction to cause SIGFPE, etc., to be raised. - Remove some compat code that is unnecessary when we fully eliminate some of the deprecated syscalls from the generic syscall ABI. - Update the tile_defconfig to reflect current config contents. Signed-off-by: Chris Metcalf Acked-by: Arnd Bergmann