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Commit 2c9120f3 authored by Will Deacon's avatar Will Deacon
Browse files

arm64: signal: Make force_signal_inject more robust 



force_signal_inject is a little flakey:

  * It only knows about SIGILL and SIGSEGV, so can potentially deliver
    other signals based on a partially initialised siginfo_t

  * It sets si_addr to point at the PC for SIGSEGV

  * It always operates on current, so doesn't need the regs argument

This patch fixes these issues by always assigning the si_addr field to
the address parameter of the function and updates the callers (including
those that indirectly call via arm64_notify_segfault) accordingly.

Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
parent e0f6429d

arch/arm64/include/asm/traps.h

+2 −4
Original line number Diff line number Diff line
@@ -35,10 +35,8 @@ struct undef_hook { 


void register_undef_hook(struct undef_hook *hook);

void unregister_undef_hook(struct undef_hook *hook);

void force_signal_inject(int signal, int code, struct pt_regs *regs,

			 unsigned long address);



void arm64_notify_segfault(struct pt_regs *regs, unsigned long addr);

void force_signal_inject(int signal, int code, unsigned long address);

void arm64_notify_segfault(unsigned long addr);



/*

 * Move regs->pc to next instruction and do necessary setup before it

arch/arm64/kernel/armv8_deprecated.c

+1 −1
Original line number Diff line number Diff line
@@ -429,7 +429,7 @@ static int swp_handler(struct pt_regs *regs, u32 instr) 


fault:

	pr_debug("SWP{B} emulation: access caused memory abort!\n");

	arm64_notify_segfault(regs, address);

	arm64_notify_segfault(address);



	return 0;

}

arch/arm64/kernel/fpsimd.c

+2 −3
Original line number Diff line number Diff line
@@ -285,8 +285,7 @@ static void task_fpsimd_save(void) 
				 * re-enter user with corrupt state.

				 * There's no way to recover, so kill it:

				 */

				force_signal_inject(

					SIGKILL, 0, current_pt_regs(), 0);

				force_signal_inject(SIGKILL, 0, 0);

				return;

			}
@@ -831,7 +830,7 @@ asmlinkage void do_sve_acc(unsigned int esr, struct pt_regs *regs) 
{

	/* Even if we chose not to use SVE, the hardware could still trap: */

	if (unlikely(!system_supports_sve()) || WARN_ON(is_compat_task())) {

		force_signal_inject(SIGILL, ILL_ILLOPC, regs, 0);

		force_signal_inject(SIGILL, ILL_ILLOPC, regs->pc);

		return;

	}

arch/arm64/kernel/traps.c

+12 −11
Original line number Diff line number Diff line
@@ -311,12 +311,13 @@ static int call_undef_hook(struct pt_regs *regs) 
	return fn ? fn(regs, instr) : 1;

}



void force_signal_inject(int signal, int code, struct pt_regs *regs,

			 unsigned long address)

void force_signal_inject(int signal, int code, unsigned long address)

{

	siginfo_t info;

	void __user *pc = (void __user *)instruction_pointer(regs);

	const char *desc;

	struct pt_regs *regs = current_pt_regs();



	clear_siginfo(&info);



	switch (signal) {

	case SIGILL:
@@ -332,15 +333,15 @@ void force_signal_inject(int signal, int code, struct pt_regs *regs, 


	if (unhandled_signal(current, signal) &&

	    show_unhandled_signals_ratelimited()) {

		pr_info("%s[%d]: %s: pc=%p\n",

			current->comm, task_pid_nr(current), desc, pc);

		pr_info("%s[%d]: %s: pc=%08llx\n",

			current->comm, task_pid_nr(current), desc, regs->pc);

		dump_instr(KERN_INFO, regs);

	}



	info.si_signo = signal;

	info.si_errno = 0;

	info.si_code  = code;

	info.si_addr  = pc;

	info.si_addr  = (void __user *)address;



	arm64_notify_die(desc, regs, &info, 0);

}
@@ -348,7 +349,7 @@ void force_signal_inject(int signal, int code, struct pt_regs *regs, 
/*

 * Set up process info to signal segmentation fault - called on access error.

 */

void arm64_notify_segfault(struct pt_regs *regs, unsigned long addr)

void arm64_notify_segfault(unsigned long addr)

{

	int code;
@@ -359,7 +360,7 @@ void arm64_notify_segfault(struct pt_regs *regs, unsigned long addr) 
		code = SEGV_ACCERR;

	up_read(&current->mm->mmap_sem);



	force_signal_inject(SIGSEGV, code, regs, addr);

	force_signal_inject(SIGSEGV, code, addr);

}



asmlinkage void __exception do_undefinstr(struct pt_regs *regs)
@@ -371,7 +372,7 @@ asmlinkage void __exception do_undefinstr(struct pt_regs *regs) 
	if (call_undef_hook(regs) == 0)

		return;



	force_signal_inject(SIGILL, ILL_ILLOPC, regs, 0);

	force_signal_inject(SIGILL, ILL_ILLOPC, regs->pc);

}



int cpu_enable_cache_maint_trap(void *__unused)
@@ -426,12 +427,12 @@ static void user_cache_maint_handler(unsigned int esr, struct pt_regs *regs) 
		__user_cache_maint("ic ivau", address, ret);

		break;

	default:

		force_signal_inject(SIGILL, ILL_ILLOPC, regs, 0);

		force_signal_inject(SIGILL, ILL_ILLOPC, regs->pc);

		return;

	}



	if (ret)

		arm64_notify_segfault(regs, address);

		arm64_notify_segfault(address);

	else

		arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE);

}