test w/ sigframe

thehajime · Dec 12, 2024 · ae5dab8 · ae5dab8
1 parent 0344dad
commit ae5dab8
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Showing 5 changed files with 20 additions and 14 deletions.
diff --git a/arch/x86/um/nommu/entry_64.S b/arch/x86/um/nommu/entry_64.S
@@ -77,19 +77,20 @@ ENTRY(__kernel_vsyscall)
 	POP_REGS
 
 	addq	$8, %rsp	/* skip orig_ax */
-	addq	$8, %rsp	/* skip ip */
+	popq	%rcx		/* pt_regs->ip */
 	addq	$8, %rsp	/* skip cs */
 	addq	$8, %rsp	/* skip flags */
 	popq	%rsp
 
-	ret
+	//popq	%rcx
+	jmp	%rcx
 
 END(__kernel_vsyscall)
 
 // void userspace(struct uml_pt_regs *regs)
 ENTRY(userspace)
 	/* fixup stack for vfork syscall*/
-	call	arch_fixup_stack
+	//call	arch_fixup_stack
 
 	/* align the stack for x86_64 ABI */
 	and     $-0x10, %rsp

diff --git a/arch/x86/um/nommu/os-Linux/mcontext.c b/arch/x86/um/nommu/os-Linux/mcontext.c
@@ -8,8 +8,9 @@
 
 static void userspace_sigreturn(void)
 {
-	__asm__ volatile("movq $15, %rax");
-	__asm__ volatile("call *%0" : : "r"(__kernel_vsyscall) :);
+	/* XXX: dummy syscall */
+	//__asm__ volatile("movq $15, %rax");
+	__asm__ volatile("call *%0" : : "r"(__kernel_vsyscall), "a"(39) :);
 }
 
 void mc_set_regs_ip_relay(mcontext_t *mc)
@@ -19,8 +20,8 @@ void mc_set_regs_ip_relay(mcontext_t *mc)
 
 void mc_set_sigsys_hook(mcontext_t *mc)
 {
-	mc->gregs[REG_RSP] -= sizeof(unsigned long);
-	*((unsigned long *) (mc->gregs[REG_RSP])) = mc->gregs[REG_RIP];
+	//mc->gregs[REG_RSP] -= sizeof(unsigned long);
+	//*((unsigned long *) (mc->gregs[REG_RSP])) = mc->gregs[REG_RIP];
 	mc->gregs[REG_RCX] = mc->gregs[REG_RIP];
 	mc->gregs[REG_RIP] = (unsigned long) __kernel_vsyscall;
 }
diff --git a/arch/x86/um/nommu/signal.c b/arch/x86/um/nommu/signal.c
@@ -6,10 +6,17 @@
 
 #include <sysdep/signal.h>
 
+/* XXX: this makes pthread_cancel, cancel_handler loops endlessly....
+if this skips, cancel works
+ */
+/* XXX: without this doesn't work with SIGSEGV */
 int arch_setup_signal_stack_si(struct rt_sigframe __user **frame,
 			       struct ksignal *ksig)
 {
 	int err = 0;
+	return 0;
+	if (ksig->sig != SIGSEGV)
+		return 0;
 
 	/*
 	 * we need to push handler address at top of stack, as

diff --git a/arch/x86/um/nommu/zpoline.c b/arch/x86/um/nommu/zpoline.c
@@ -209,11 +209,8 @@ static int __init setup_zpoline_trampoline(void)
 	 * pretending to be syscall instruction by putting return
 	 * address in %rcx.
 	 */
-	/* 48 8b 0c 24               mov    (%rsp),%rcx */
-	__zpoline_start[ptr++] = 0x48;
-	__zpoline_start[ptr++] = 0x8b;
-	__zpoline_start[ptr++] = 0x0c;
-	__zpoline_start[ptr++] = 0x24;
+	/* 59                   pop    %rcx */
+	__zpoline_start[ptr++] = 0x59;
 
 	/* 41 ff e3                jmp    *%r11 */
 	__zpoline_start[ptr++] = 0x41;

diff --git a/arch/x86/um/signal.c b/arch/x86/um/signal.c
@@ -427,7 +427,7 @@ int setup_signal_stack_si(unsigned long stack_top, struct ksignal *ksig,
 		return err;
 
 	/* fixup rt_sigframe for nommu */
-	err |= arch_setup_signal_stack_si(&frame, ksig);
+	//err |= arch_setup_signal_stack_si(&frame, ksig);
 	if (err)
 		return err;
 
@@ -457,7 +457,7 @@ SYSCALL_DEFINE0(rt_sigreturn)
 	sigset_t set;
 
 	/* fixup rt_sigframe for nommu */
-	frame = arch_setup_rt_sigreturn(frame);
+	//frame = arch_setup_rt_sigreturn(frame);
 	uc = &frame->uc;
 
 	if (copy_from_user(&set, &uc->uc_sigmask, sizeof(set)))