- 23 11月, 2005 2 次提交
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由 Jeff Dike 提交于
On some systems, libc PAGE_SIZE calls getpagesize, which can't happen from a stub. So, I use UM_KERN_PAGE_SIZE, which is less variable in its definition, instead. Signed-off-by: NJeff Dike <jdike@addtoit.com> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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由 Jeff Dike 提交于
We have a bug in the i386 stub_syscall6 which pushes ebp before the system call and pops it afterwards. Because we use syscall6 to remap the stack, the old contents of the stack (and the former value of ebp) are no longer available. Some versions of gcc make from a real local, accessed through ebp, despite my efforts to make it obvious that references to from are really constants. This patch attempts to make it even more obvious by eliminating from and using a macro to access the stub's data explicitly with constants. My original thinking on this was to replace syscall6 with a remap_stack interface which saved ebp someplace and restored it afterwards. The problem is that there are no registers to put it in, except for esp. That could work, since we can store a constant in esp after the mmap because we just replaced the stack. However, this approach seems a tad cleaner. Signed-off-by: NJeff Dike <jdike@addtoit.com> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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- 08 7月, 2005 1 次提交
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由 Bodo Stroesser 提交于
This patch implements the clone-stub mechanism, which allows skas0 to run with proc_mm==0, even if the clib in UML uses modify_ldt. Note: There is a bug in skas3.v7 host patch, that avoids UML-skas from running properly on a SMP-box. In full skas3, I never really saw problems, but in skas0 they showed up. More commentary by jdike - What this patch does is makes sure that the host parent of each new host process matches the UML parent of the corresponding UML process. This ensures that any changed LDTs are inherited. This is done by having clone actually called by the UML process from its stub, rather than by the kernel. We have special syscall stubs that are loaded onto the stub code page because that code must be completely self-contained. These stubs are given C interfaces, and used like normal C functions, but there are subtleties. Principally, we have to be careful about stack variables in stub_clone_handler after the clone. The code is written so that there aren't any - everything boils down to a fixed address. If there were any locals, references to them after the clone would be wrong because the stack just changed. Signed-off-by: NBodo Stroesser <bstroesser@fujitsu-siemens.com> Signed-off-by: NJeff Dike <jdike@addtoit.com> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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