Hi, On Wed, 2022-02-16 at 15:07 +0100, Mark Wielaard wrote: > The code in ppc_initreg.c used PTRACE_PEEKUSER to fetch all registers > one by one. Which is slightly inefficient. It did this because it > wanted > things to work on linux 2.6.18 which didn't support PTRACE_GETREGSET. > > PTRACE_GETREGSET was only officially since 2.6.34 (but backported > to some earlier versions). It seems ok to require a linux kernel that > supports PTRACE_GETREGSET now. This is much more efficient since it > takes just one ptrace call instead of 44 calls to fetch each register > individually. > > For some really old versions we need to include <linux/ptrace.h> to > get PTRACE_GETREGSET defined. And on ppc64 there is no 32bit version > of struct pt_regs available, so we define that ourselves and check > how much data is returned to know whether this is a full pt_regs or > one for a 32bit process. An alternative would be to use the raw > iov_base bytes with 64bit or 32bit offset constants to get at the > registers instead of using a struct with names. > > The code works for inspecting a 32bit process from a 64bit build, > but not the other way around (the previous code also didn't). This > could work if we also defined and used a 64bit pt_regs struct on > ppc32. But it seems a use case that is not really used (it was hard > enough finding ppc32 setups to test this on). > > Tested against ppc and ppc64 on linux 2.6.32 and glibc 2.12 and > ppc and ppc64 on linux 3.10.0 with glibc 2.17.
Pushed. Cheers, Mark
