ARC: ptrace support (547f1125) · Commits · e / devices / android_kernel_fairphone_FP4

arch/arc/Kconfig

+1 −0

Original line number	Diff line number	Diff line
		@@ -22,6 +22,7 @@ config ARC
		select GENERIC_PENDING_IRQ if SMP
		select GENERIC_SIGALTSTACK
		select GENERIC_SMP_IDLE_THREAD
		select HAVE_ARCH_TRACEHOOK
		select HAVE_GENERIC_HARDIRQS
		select HAVE_MEMBLOCK
		select IRQ_DOMAIN

arch/arc/kernel/Makefile

+3 −0

Original line number	Diff line number	Diff line
		@@ -5,6 +5,9 @@
		# it under the terms of the GNU General Public License version 2 as
		# published by the Free Software Foundation.

		# Pass UTS_MACHINE for user_regset definition
		CFLAGS_ptrace.o += -DUTS_MACHINE='"$(UTS_MACHINE)"'

		obj-y := arcksyms.o setup.o irq.o time.o reset.o ptrace.o entry.o process.o
		obj-y += signal.o traps.o sys.o troubleshoot.o stacktrace.o clk.o
		obj-y += devtree.o

arch/arc/kernel/entry.S

+68 −0

Original line number	Diff line number	Diff line
		@@ -7,6 +7,13 @@
		* it under the terms of the GNU General Public License version 2 as
		* published by the Free Software Foundation.
		*
		* vineetg: Feb 2011 (ptrace low level code fixes)
		* -traced syscall return code (r0) was not saved into pt_regs for restoring
		* into user reg-file when traded task rets to user space.
		* -syscalls needing arch-wrappers (mainly for passing sp as pt_regs)
		* were not invoking post-syscall trace hook (jumping directly into
		* ret_from_system_call)
		*
		* vineetg: Nov 2010:
		* -Vector table jumps (@8 bytes) converted into branches (@4 bytes)
		* -To maintain the slot size of 8 bytes/vector, added nop, which is
		@@ -347,6 +354,50 @@ ARC_ENTRY EV_Extension
		b ret_from_exception
		ARC_EXIT EV_Extension

		;######################### System Call Tracing #########################

		tracesys:
		; save EFA in case tracer wants the PC of traced task
		; using ERET won't work since next-PC has already committed
		lr r12, [efa]
		GET_CURR_TASK_FIELD_PTR TASK_THREAD, r11
		st r12, [r11, THREAD_FAULT_ADDR]

		; PRE Sys Call Ptrace hook
		mov r0, sp ; pt_regs needed
		bl @syscall_trace_entry

		; Tracing code now returns the syscall num (orig or modif)
		mov r8, r0

		; Do the Sys Call as we normally would.
		; Validate the Sys Call number
		cmp r8, NR_syscalls
		mov.hi r0, -ENOSYS
		bhi tracesys_exit

		; Restore the sys-call args. Mere invocation of the hook abv could have
		; clobbered them (since they are in scratch regs). The tracer could also
		; have deliberately changed the syscall args: r0-r7
		ld r0, [sp, PT_r0]
		ld r1, [sp, PT_r1]
		ld r2, [sp, PT_r2]
		ld r3, [sp, PT_r3]
		ld r4, [sp, PT_r4]
		ld r5, [sp, PT_r5]
		ld r6, [sp, PT_r6]
		ld r7, [sp, PT_r7]
		ld.as r9, [sys_call_table, r8]
		jl [r9] ; Entry into Sys Call Handler

		tracesys_exit:
		st r0, [sp, PT_r0] ; sys call return value in pt_regs

		;POST Sys Call Ptrace Hook
		bl @syscall_trace_exit
		b ret_from_exception ; NOT ret_from_system_call at is saves r0 which
		; we'd done before calling post hook above

		;################### Break Point TRAP ##########################

		; ======= (5b) Trap is due to Break-Point =========
		@@ -412,6 +463,11 @@ ARC_ENTRY EV_Trap
		; Before doing anything, return from CPU Exception Mode
		FAKE_RET_FROM_EXCPN r11

		; If syscall tracing ongoing, invoke pre-pos-hooks
		GET_CURR_THR_INFO_FLAGS r10
		btst r10, TIF_SYSCALL_TRACE
		bnz tracesys ; this never comes back

		;============ This is normal System Call case ==========
		; Sys-call num shd not exceed the total system calls avail
		cmp r8, NR_syscalls
		@@ -608,6 +664,10 @@ ARC_ENTRY sys_fork_wrapper
		bl @sys_fork
		DISCARD_CALLEE_SAVED_USER

		GET_CURR_THR_INFO_FLAGS r10
		btst r10, TIF_SYSCALL_TRACE
		bnz tracesys_exit

		b ret_from_system_call
		ARC_EXIT sys_fork_wrapper

		@@ -616,6 +676,10 @@ ARC_ENTRY sys_vfork_wrapper
		bl @sys_vfork
		DISCARD_CALLEE_SAVED_USER

		GET_CURR_THR_INFO_FLAGS r10
		btst r10, TIF_SYSCALL_TRACE
		bnz tracesys_exit

		b ret_from_system_call
		ARC_EXIT sys_vfork_wrapper

		@@ -624,5 +688,9 @@ ARC_ENTRY sys_clone_wrapper
		bl @sys_clone
		DISCARD_CALLEE_SAVED_USER

		GET_CURR_THR_INFO_FLAGS r10
		btst r10, TIF_SYSCALL_TRACE
		bnz tracesys_exit

		b ret_from_system_call
		ARC_EXIT sys_clone_wrapper

arch/arc/kernel/ptrace.c

+134 −2

Original line number	Diff line number	Diff line
		@@ -7,6 +7,122 @@
		*/

		#include <linux/ptrace.h>
		#include <linux/tracehook.h>
		#include <linux/regset.h>
		#include <linux/unistd.h>
		#include <linux/elf.h>

		static struct callee_regs task_callee_regs(struct task_struct tsk)
		{
		struct callee_regs tmp = (struct callee_regs )tsk->thread.callee_reg;
		return tmp;
		}

		static int genregs_get(struct task_struct *target,
		const struct user_regset *regset,
		unsigned int pos, unsigned int count,
		void kbuf, void __user ubuf)
		{
		const struct pt_regs *ptregs = task_pt_regs(target);
		const struct callee_regs *cregs = task_callee_regs(target);
		int ret = 0;
		unsigned int stop_pc_val;

		#define REG_O_CHUNK(START, END, PTR) \
		if (!ret) \
		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, PTR, \
		offsetof(struct user_regs_struct, START), \
		offsetof(struct user_regs_struct, END));

		#define REG_O_ONE(LOC, PTR) \
		if (!ret) \
		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, PTR, \
		offsetof(struct user_regs_struct, LOC), \
		offsetof(struct user_regs_struct, LOC) + 4);

		REG_O_CHUNK(scratch, callee, ptregs);
		REG_O_CHUNK(callee, efa, cregs);
		REG_O_CHUNK(efa, stop_pc, &target->thread.fault_address);

		if (!ret) {
		if (in_brkpt_trap(ptregs)) {
		stop_pc_val = target->thread.fault_address;
		pr_debug("\t\tstop_pc (brk-pt)\n");
		} else {
		stop_pc_val = ptregs->ret;
		pr_debug("\t\tstop_pc (others)\n");
		}

		REG_O_ONE(stop_pc, &stop_pc_val);
		}

		return ret;
		}

		static int genregs_set(struct task_struct *target,
		const struct user_regset *regset,
		unsigned int pos, unsigned int count,
		const void kbuf, const void __user ubuf)
		{
		const struct pt_regs *ptregs = task_pt_regs(target);
		const struct callee_regs *cregs = task_callee_regs(target);
		int ret = 0;

		#define REG_IN_CHUNK(FIRST, NEXT, PTR) \
		if (!ret) \
		ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, \
		(void *)(PTR), \
		offsetof(struct user_regs_struct, FIRST), \
		offsetof(struct user_regs_struct, NEXT));

		#define REG_IN_ONE(LOC, PTR) \
		if (!ret) \
		ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, \
		(void *)(PTR), \
		offsetof(struct user_regs_struct, LOC), \
		offsetof(struct user_regs_struct, LOC) + 4);

		#define REG_IGNORE_ONE(LOC) \
		if (!ret) \
		ret = user_regset_copyin_ignore(&pos, &count, &kbuf, &ubuf, \
		offsetof(struct user_regs_struct, LOC), \
		offsetof(struct user_regs_struct, LOC) + 4);

		/* TBD: disallow updates to STATUS32, orig_r8 etc*/
		REG_IN_CHUNK(scratch, callee, ptregs); /* pt_regs[bta..orig_r8] */
		REG_IN_CHUNK(callee, efa, cregs); /* callee_regs[r25..r13] */
		REG_IGNORE_ONE(efa); /* efa update invalid */
		REG_IN_ONE(stop_pc, &ptregs->ret); /* stop_pc: PC update */

		return ret;
		}

		enum arc_getset {
		REGSET_GENERAL,
		};

		static const struct user_regset arc_regsets[] = {
		[REGSET_GENERAL] = {
		.core_note_type = NT_PRSTATUS,
		.n = ELF_NGREG,
		.size = sizeof(unsigned long),
		.align = sizeof(unsigned long),
		.get = genregs_get,
		.set = genregs_set,
		}
		};

		static const struct user_regset_view user_arc_view = {
		.name = UTS_MACHINE,
		.e_machine = EM_ARCOMPACT,
		.regsets = arc_regsets,
		.n = ARRAY_SIZE(arc_regsets)
		};

		const struct user_regset_view task_user_regset_view(struct task_struct task)
		{
		return &user_arc_view;
		}

		void ptrace_disable(struct task_struct *child)
		{
		@@ -16,11 +132,27 @@ long arch_ptrace(struct task_struct *child, long request,
		unsigned long addr, unsigned long data)
		{
		int ret = -EIO;

		pr_debug("REQ=%ld: ADDR =0x%lx, DATA=0x%lx)\n", request, addr, data);

		switch (request) {
		default:
		ret = ptrace_request(child, request, addr, data);
		break;
		}

		return ret;
		}

		asmlinkage int syscall_trace_entry(struct pt_regs *regs)
		{
		if (tracehook_report_syscall_entry(regs))
		return ULONG_MAX;

		const struct user_regset_view task_user_regset_view(struct task_struct task)
		return regs->r8;
		}

		asmlinkage void syscall_trace_exit(struct pt_regs *regs)
		{
		return (const struct user_regset_view *)NULL;
		tracehook_report_syscall_exit(regs, 0);
		}