Unable to compile on Debian 9.3, i686 (as in 32 bit)

[seefood]

# make
g++ -I. --std=c++11 -O0 --no-pie -fPIC -mrtm -DHAS_COMPILER_RTM_SUPPORT -c -o meltdown_checker.o meltdown_checker.cc 
meltdown_checker.cc: In function ‘void transaction_trap_mitigation(int, siginfo_t*, void*)’:
meltdown_checker.cc:82:32: error: ‘REG_RIP’ was not declared in this scope
     context->uc_mcontext.gregs[REG_RIP] = (uintptr_t)__speculative_byte_load_exit;
                                ^~~~~~~
meltdown_checker.cc: In function ‘bool validate_syscall_table_entry(const void*, const std::unordered_map<unsigned int, std::__cxx11::basic_string<char> >&)’:
meltdown_checker.cc:165:57: error: invalid cast from type ‘uint64_t {aka long long unsigned int}’ to type ‘uintptr_t {aka unsigned int}’
     uintptr_t ptr = reinterpret_cast<uintptr_t>(entry[0]);
                                                         ^
Makefile:12: recipe for target 'meltdown_checker.o' failed

gcc version 6.3.0 20170516 (Debian 6.3.0-18), Debian 9.3

[raphaelsc]

oops. thanks for pointing it out @seefood

[seefood]

:bowing_man:

[seefood]

Only problem now: I already upgraded the kernel on that machine, now I'm not sure if that CPU was vulnerable (it's not in the lists I've searched, it's an 11 YO model of Xeon) or if I should turn off the protection. hmm!

[raphaelsc]

If you want to confirm it without compromising security, reboot with pti disabled and run the test offline. Good luck!

[seefood]

yeah, the point is I didn't want to reboot it too much... it's an old server but people still rely on it... oddly enough, it's a Debian kernel that's supposed to include the KPTI patch but /boot/config-4.9.0-5-686-pae has no CONFIG_PAGE_TABLE_ISOLATION

weirder and weirder. for now I'll assume that old machine has no kernel patch but no CPU vulnerability either. I'll try to find some answers on IRC or something. Also, I'm no able to build the sources they offer in the original whitepaper on any machine and my C is rusty. Hmm :)

[seefood]

the IRC people said the 32 bit kernel isn't patched because meltdown only affects CPUs working in 64bit mode. I'll go read more on that. sounds weird to me.