Commit 247ed9e4 authored by Benjamin Berg's avatar Benjamin Berg Committed by Johannes Berg
Browse files

um: Move faultinfo extraction into userspace routine 



The segv handler is called slightly differently depending on whether
PTRACE_FULL_FAULTINFO is set or not (32bit vs. 64bit). The only
difference is that we don't try to pass the registers and instruction
pointer to the segv handler.

It would be good to either document or remove the difference, but I do
not know why this difference exists. And, passing NULL can even result
in a crash.

Signed-off-by: default avatarBenjamin Berg <benjamin@sipsolutions.net>
Link: https://patch.msgid.link/20250602130052.545733-2-benjamin@sipsolutions.net


Signed-off-by: default avatarJohannes Berg <johannes.berg@intel.com>
parent b76d18b5

arch/um/os-Linux/skas/process.c

+6 −11
Original line number Diff line number Diff line
@@ -163,12 +163,6 @@ static void get_skas_faultinfo(int pid, struct faultinfo *fi) 
	memcpy(fi, (void *)current_stub_stack(), sizeof(*fi));

}



static void handle_segv(int pid, struct uml_pt_regs *regs)

{

	get_skas_faultinfo(pid, &regs->faultinfo);

	segv(regs->faultinfo, 0, 1, NULL, NULL);

}



static void handle_trap(int pid, struct uml_pt_regs *regs)

{

	if ((UPT_IP(regs) >= STUB_START) && (UPT_IP(regs) < STUB_END))
@@ -521,13 +515,14 @@ void userspace(struct uml_pt_regs *regs) 


			switch (sig) {

			case SIGSEGV:

				if (PTRACE_FULL_FAULTINFO) {

					get_skas_faultinfo(pid,

							   &regs->faultinfo);

				get_skas_faultinfo(pid, &regs->faultinfo);



				if (PTRACE_FULL_FAULTINFO)

					(*sig_info[SIGSEGV])(SIGSEGV, (struct siginfo *)&si,

							     regs, NULL);

				}

				else handle_segv(pid, regs);

				else

					segv(regs->faultinfo, 0, 1, NULL, NULL);



				break;

			case SIGTRAP + 0x80:

				handle_trap(pid, regs);