libucontext

Commit Graph

Author	SHA1	Message	Date
Bobby Bingham	2610c7faa7	ppc32/64: rewrite get/set/swapcontext in assembly getcontext cannot be correctly implemented in C. If this calls another function, as it does to call syscall, it needs to first spill its return address to the stack. If, after getcontext returns, its caller then calls other functions, this saved return address can be clobbered. When the context saved by getcontext is later restored, the (now clobbered) return address will be reloaded from the stack, and the second return from getcontext will return to the wrong location. Because the powerpc swapcontext syscall allows either the old context or new context pointers to be null, it is usable for implementing all of get/set/swapcontext. We therefore rewrite swapcontext in assembly, and get/setcontext as simple assembly function wrappers around swapcontext. The one piece we keep in C is the code to check the return value of the system call and to set errno. This code was actually unnecessary before -- libc does this within syscall. However, now that the system call is made directly in assembly, bypassing libc, it is truly necessary. Because errno is thread-local and the details of how to set it can vary by libc, this code remains written in C.	2019-04-05 14:44:54 -05:00
William Pitcock	7b1a302ed4	README: we support s390x now	2018-02-15 05:55:26 +00:00
William Pitcock	79415db5a8	README: update for 0.1.0	2018-02-14 03:06:01 +00:00
William Pitcock	71979e9cf6	arch: ppc64: now working	2018-02-06 08:05:53 +00:00
William Pitcock	8ff8bb3280	README: note that ppc implementation uses kernel assistance	2018-02-02 18:51:55 +00:00
William Pitcock	f3fe8ea781	arch: ppc: new port	2018-02-02 18:46:21 +00:00
William Pitcock	66919bb222	README: x86 now supported	2018-02-01 01:28:19 +00:00
William Pitcock	13283f5eba	arch: add aarch64 port	2018-01-31 21:23:18 +00:00
William Pitcock	e43fc2698a	README: we support ARM	2018-01-31 04:13:42 +00:00
William Pitcock	0e437d3fc7	add README	2018-01-30 03:56:01 +00:00

10 Commits (5f137a1fe4844fdd5c147727d360ed4cd818b563)