Commit 95b980a0 authored by Jordan Niethe's avatar Jordan Niethe Committed by Michael Ellerman
Browse files

powerpc: Add a probe_kernel_read_inst() function 



Introduce a probe_kernel_read_inst() function to use in cases where
probe_kernel_read() is used for getting an instruction. This will be
more useful for prefixed instructions.

Signed-off-by: default avatarJordan Niethe <jniethe5@gmail.com>
Reviewed-by: default avatarAlistair Popple <alistair@popple.id.au>
[mpe: Don't write to *inst on error]
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200506034050.24806-15-jniethe5@gmail.com
parent 7ba68b21

arch/powerpc/include/asm/inst.h

+3 −0
Original line number Diff line number Diff line
@@ -40,4 +40,7 @@ static inline bool ppc_inst_equal(struct ppc_inst x, struct ppc_inst y) 
int probe_user_read_inst(struct ppc_inst *inst,

			 struct ppc_inst __user *nip);



int probe_kernel_read_inst(struct ppc_inst *inst,

			   struct ppc_inst *src);



#endif /* _ASM_POWERPC_INST_H */

arch/powerpc/kernel/trace/ftrace.c

+13 −10
Original line number Diff line number Diff line
@@ -68,7 +68,7 @@ ftrace_modify_code(unsigned long ip, struct ppc_inst old, struct ppc_inst new) 
	 */



	/* read the text we want to modify */

	if (probe_kernel_read(&replaced, (void *)ip, MCOUNT_INSN_SIZE))

	if (probe_kernel_read_inst(&replaced, (void *)ip))

		return -EFAULT;



	/* Make sure it is what we expect it to be */
@@ -130,7 +130,7 @@ __ftrace_make_nop(struct module *mod, 
	struct ppc_inst op, pop;



	/* read where this goes */

	if (probe_kernel_read(&op, (void *)ip, sizeof(int))) {

	if (probe_kernel_read_inst(&op, (void *)ip)) {

		pr_err("Fetching opcode failed.\n");

		return -EFAULT;

	}
@@ -164,7 +164,7 @@ __ftrace_make_nop(struct module *mod, 
	/* When using -mkernel_profile there is no load to jump over */

	pop = ppc_inst(PPC_INST_NOP);



	if (probe_kernel_read(&op, (void *)(ip - 4), 4)) {

	if (probe_kernel_read_inst(&op, (void *)(ip - 4))) {

		pr_err("Fetching instruction at %lx failed.\n", ip - 4);

		return -EFAULT;

	}
@@ -197,7 +197,7 @@ __ftrace_make_nop(struct module *mod, 
	 * Check what is in the next instruction. We can see ld r2,40(r1), but

	 * on first pass after boot we will see mflr r0.

	 */

	if (probe_kernel_read(&op, (void *)(ip+4), MCOUNT_INSN_SIZE)) {

	if (probe_kernel_read_inst(&op, (void *)(ip + 4))) {

		pr_err("Fetching op failed.\n");

		return -EFAULT;

	}
@@ -349,7 +349,7 @@ static int setup_mcount_compiler_tramp(unsigned long tramp) 
			return -1;



	/* New trampoline -- read where this goes */

	if (probe_kernel_read(&op, (void *)tramp, sizeof(int))) {

	if (probe_kernel_read_inst(&op, (void *)tramp)) {

		pr_debug("Fetching opcode failed.\n");

		return -1;

	}
@@ -399,7 +399,7 @@ static int __ftrace_make_nop_kernel(struct dyn_ftrace *rec, unsigned long addr) 
	struct ppc_inst op;



	/* Read where this goes */

	if (probe_kernel_read(&op, (void *)ip, sizeof(int))) {

	if (probe_kernel_read_inst(&op, (void *)ip)) {

		pr_err("Fetching opcode failed.\n");

		return -EFAULT;

	}
@@ -526,7 +526,10 @@ __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) 
	struct module *mod = rec->arch.mod;



	/* read where this goes */

	if (probe_kernel_read(op, ip, sizeof(op)))

	if (probe_kernel_read_inst(op, ip))

		return -EFAULT;



	if (probe_kernel_read_inst(op + 1, ip + 4))

		return -EFAULT;



	if (!expected_nop_sequence(ip, op[0], op[1])) {
@@ -589,7 +592,7 @@ __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) 
	unsigned long ip = rec->ip;



	/* read where this goes */

	if (probe_kernel_read(&op, (void *)ip, MCOUNT_INSN_SIZE))

	if (probe_kernel_read_inst(&op, (void *)ip))

		return -EFAULT;



	/* It should be pointing to a nop */
@@ -645,7 +648,7 @@ static int __ftrace_make_call_kernel(struct dyn_ftrace *rec, unsigned long addr) 
	}



	/* Make sure we have a nop */

	if (probe_kernel_read(&op, ip, sizeof(op))) {

	if (probe_kernel_read_inst(&op, ip)) {

		pr_err("Unable to read ftrace location %p\n", ip);

		return -EFAULT;

	}
@@ -723,7 +726,7 @@ __ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, 
	}



	/* read where this goes */

	if (probe_kernel_read(&op, (void *)ip, sizeof(int))) {

	if (probe_kernel_read_inst(&op, (void *)ip)) {

		pr_err("Fetching opcode failed.\n");

		return -EFAULT;

	}

arch/powerpc/lib/inst.c

+13 −0
Original line number Diff line number Diff line
@@ -18,3 +18,16 @@ int probe_user_read_inst(struct ppc_inst *inst, 


	return err;

}



int probe_kernel_read_inst(struct ppc_inst *inst,

			   struct ppc_inst *src)

{

	unsigned int val;

	int err;



	err = probe_kernel_read(&val, src, sizeof(val));

	if (!err)

		*inst = ppc_inst(val);



	return err;

}

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