powerpc/xmon: Move breakpoints to text section

The instructions for xmon's breakpoint are stored bpt_table[] which is in
the data section. This is problematic as the data section may be marked
as no execute. Move bpt_table[] to the text section.
Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200506034050.24806-4-jniethe5@gmail.com

arch/powerpc/kernel/asm-offsets.c

@@ -70,6 +70,10 @@
 #include <asm/fixmap.h>
 #endif
 
+#ifdef CONFIG_XMON
+#include "../xmon/xmon_bpts.h"
+#endif
+
 #define STACK_PT_REGS_OFFSET(sym, val)	\
 	DEFINE(sym, STACK_FRAME_OVERHEAD + offsetof(struct pt_regs, val))
 
@@ -795,5 +799,9 @@ int main(void)
 	DEFINE(VIRT_IMMR_BASE, (u64)__fix_to_virt(FIX_IMMR_BASE));
 #endif
 
+#ifdef CONFIG_XMON
+	DEFINE(BPT_SIZE, BPT_SIZE);
+#endif
+
 	return 0;
 }

arch/powerpc/xmon/Makefile

@@ -18,7 +18,7 @@ endif
 
 ccflags-$(CONFIG_PPC64) := $(NO_MINIMAL_TOC)
 
-obj-y			+= xmon.o nonstdio.o spr_access.o
+obj-y			+= xmon.o nonstdio.o spr_access.o xmon_bpts.o
 
 ifdef CONFIG_XMON_DISASSEMBLY
 obj-y			+= ppc-dis.o ppc-opc.o

arch/powerpc/xmon/xmon.c

@@ -62,6 +62,7 @@
 
 #include "nonstdio.h"
 #include "dis-asm.h"
+#include "xmon_bpts.h"
 
 #ifdef CONFIG_SMP
 static cpumask_t cpus_in_xmon = CPU_MASK_NONE;
@@ -109,7 +110,6 @@ struct bpt {
 #define BP_TRAP		2
 #define BP_DABR		4
 
-#define NBPTS	256
 static struct bpt bpts[NBPTS];
 static struct bpt dabr;
 static struct bpt *iabr;
@@ -117,10 +117,6 @@ static unsigned bpinstr = 0x7fe00008;	/* trap */
 
 #define BP_NUM(bp)	((bp) - bpts + 1)
 
-#define BPT_SIZE       (sizeof(unsigned int) * 2)
-#define BPT_WORDS      (BPT_SIZE / sizeof(unsigned int))
-static unsigned int bpt_table[NBPTS * BPT_WORDS];
-
 /* Prototypes */
 static int cmds(struct pt_regs *);
 static int mread(unsigned long, void *, int);

arch/powerpc/xmon/xmon_bpts.S

+/* SPDX-License-Identifier: GPL-2.0 */
+#include <asm/ppc_asm.h>
+#include <asm/asm-compat.h>
+#include <asm/asm-offsets.h>
+#include "xmon_bpts.h"
+
+.global bpt_table
+bpt_table:
+	.space NBPTS * BPT_SIZE

arch/powerpc/xmon/xmon_bpts.h

+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef XMON_BPTS_H
+#define XMON_BPTS_H
+
+#define NBPTS	256
+#ifndef __ASSEMBLY__
+#define BPT_SIZE	(sizeof(unsigned int) * 2)
+#define BPT_WORDS	(BPT_SIZE / sizeof(unsigned int))
+
+extern unsigned int bpt_table[NBPTS * BPT_WORDS];
+
+#endif /* __ASSEMBLY__ */
+
+#endif /* XMON_BPTS_H */