[PATCH] PPC64 move emulate_step to arch/ppc64/lib

From: Paul Mackerras
Date: Wed Nov 17 2004 - 20:06:05 EST

Next message: John McCutchan: "Re: [patch] inotify: add sysfs store support"
Previous message: Chris Ross: "Re: [PATCH] Remove OOM killer from try_to_free_pages / all_unreclaimablebraindamage"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

This patch moves the emulate_step function, which is used in xmon's
single-stepping code, out of xmon.c and into arch/ppc64/lib/sstep.c,
so that kprobes can use it too.

Andrew: if you prefer to defer this until after 2.6.10, that's OK, but
I think it would be safe to go in now, since the only thing it can
break is xmon.

Signed-off-by: Paul Mackerras <paulus@xxxxxxxxx>

diff -urN linux-2.5/arch/ppc64/lib/Makefile test/arch/ppc64/lib/Makefile
--- linux-2.5/arch/ppc64/lib/Makefile 2004-07-12 09:12:03.000000000 +1000
+++ test/arch/ppc64/lib/Makefile 2004-11-18 11:14:04.180366608 +1100
@@ -15,3 +15,4 @@
obj-$(CONFIG_PCI) += e2a.o
endif

+lib-$(CONFIG_XMON) += sstep.o
diff -urN linux-2.5/arch/ppc64/lib/sstep.c test/arch/ppc64/lib/sstep.c
--- /dev/null 2004-08-12 23:33:25.000000000 +1000
+++ test/arch/ppc64/lib/sstep.c 2004-11-18 11:21:40.464360680 +1100
@@ -0,0 +1,141 @@
+/*
+ * Single-step support.
+ *
+ * Copyright (C) 2004 Paul Mackerras <paulus@xxxxxxxxxx>, IBM
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+#include <linux/kernel.h>
+#include <linux/ptrace.h>
+#include <asm/sstep.h>
+#include <asm/processor.h>
+
+extern char SystemCall_common[];
+
+/* Bits in SRR1 that are copied from MSR */
+#define MSR_MASK 0xffffffff87c0ffff
+
+/*
+ * Determine whether a conditional branch instruction would branch.
+ */
+static int branch_taken(unsigned int instr, struct pt_regs *regs)
+{
+ unsigned int bo = (instr >> 21) & 0x1f;
+ unsigned int bi;
+
+ if ((bo & 4) == 0) {
+ /* decrement counter */
+ --regs->ctr;
+ if (((bo >> 1) & 1) ^ (regs->ctr == 0))
+ return 0;
+ }
+ if ((bo & 0x10) == 0) {
+ /* check bit from CR */
+ bi = (instr >> 16) & 0x1f;
+ if (((regs->ccr >> (31 - bi)) & 1) != ((bo >> 3) & 1))
+ return 0;
+ }
+ return 1;
+}
+
+/*
+ * Emulate instructions that cause a transfer of control.
+ * Returns 1 if the step was emulated, 0 if not,
+ * or -1 if the instruction is one that should not be stepped,
+ * such as an rfid, or a mtmsrd that would clear MSR_RI.
+ */
+int emulate_step(struct pt_regs *regs, unsigned int instr)
+{
+ unsigned int opcode, rd;
+ unsigned long int imm;
+
+ opcode = instr >> 26;
+ switch (opcode) {
+ case 16: /* bc */
+ imm = (signed short)(instr & 0xfffc);
+ if ((instr & 2) == 0)
+ imm += regs->nip;
+ regs->nip += 4;
+ if ((regs->msr & MSR_SF) == 0)
+ regs->nip &= 0xffffffffUL;
+ if (instr & 1)
+ regs->link = regs->nip;
+ if (branch_taken(instr, regs))
+ regs->nip = imm;
+ return 1;
+ case 17: /* sc */
+ /*
+ * N.B. this uses knowledge about how the syscall
+ * entry code works. If that is changed, this will
+ * need to be changed also.
+ */
+ regs->gpr[9] = regs->gpr[13];
+ regs->gpr[11] = regs->nip + 4;
+ regs->gpr[12] = regs->msr & MSR_MASK;
+ regs->gpr[13] = (unsigned long) get_paca();
+ regs->nip = (unsigned long) &SystemCall_common;
+ regs->msr = MSR_KERNEL;
+ return 1;
+ case 18: /* b */
+ imm = instr & 0x03fffffc;
+ if (imm & 0x02000000)
+ imm -= 0x04000000;
+ if ((instr & 2) == 0)
+ imm += regs->nip;
+ if (instr & 1) {
+ regs->link = regs->nip + 4;
+ if ((regs->msr & MSR_SF) == 0)
+ regs->link &= 0xffffffffUL;
+ }
+ if ((regs->msr & MSR_SF) == 0)
+ imm &= 0xffffffffUL;
+ regs->nip = imm;
+ return 1;
+ case 19:
+ switch (instr & 0x7fe) {
+ case 0x20: /* bclr */
+ case 0x420: /* bcctr */
+ imm = (instr & 0x400)? regs->ctr: regs->link;
+ regs->nip += 4;
+ if ((regs->msr & MSR_SF) == 0) {
+ regs->nip &= 0xffffffffUL;
+ imm &= 0xffffffffUL;
+ }
+ if (instr & 1)
+ regs->link = regs->nip;
+ if (branch_taken(instr, regs))
+ regs->nip = imm;
+ return 1;
+ case 0x24: /* rfid, scary */
+ return -1;
+ }
+ case 31:
+ rd = (instr >> 21) & 0x1f;
+ switch (instr & 0x7fe) {
+ case 0xa6: /* mfmsr */
+ regs->gpr[rd] = regs->msr & MSR_MASK;
+ regs->nip += 4;
+ if ((regs->msr & MSR_SF) == 0)
+ regs->nip &= 0xffffffffUL;
+ return 1;
+ case 0x164: /* mtmsrd */
+ /* only MSR_EE and MSR_RI get changed if bit 15 set */
+ /* mtmsrd doesn't change MSR_HV and MSR_ME */
+ imm = (instr & 0x10000)? 0x8002: 0xefffffffffffefffUL;
+ imm = (regs->msr & MSR_MASK & ~imm)
+ | (regs->gpr[rd] & imm);
+ if ((imm & MSR_RI) == 0)
+ /* can't step mtmsrd that would clear MSR_RI */
+ return -1;
+ regs->msr = imm;
+ regs->nip += 4;
+ if ((imm & MSR_SF) == 0)
+ regs->nip &= 0xffffffffUL;
+ return 1;
+ }
+ }
+ return 0;
+}
diff -urN linux-2.5/arch/ppc64/xmon/xmon.c test/arch/ppc64/xmon/xmon.c
--- linux-2.5/arch/ppc64/xmon/xmon.c 2004-10-26 16:06:41.000000000 +1000
+++ test/arch/ppc64/xmon/xmon.c 2004-11-18 11:21:33.745317056 +1100
@@ -31,6 +31,7 @@
#include <asm/ppcdebug.h>
#include <asm/cputable.h>
#include <asm/rtas.h>
+#include <asm/sstep.h>

#include "nonstdio.h"
#include "privinst.h"
@@ -85,9 +86,6 @@

#define BP_NUM(bp) ((bp) - bpts + 1)

-/* Bits in SRR1 that are copied from MSR */
-#define MSR_MASK 0xffffffff87c0ffff
-
/* Prototypes */
static int cmds(struct pt_regs *);
static int mread(unsigned long, void *, int);
@@ -132,7 +130,6 @@
static void bootcmds(void);
void dump_segments(void);
static void symbol_lookup(void);
-static int emulate_step(struct pt_regs *regs, unsigned int instr);
static void xmon_print_symbol(unsigned long address, const char *mid,
const char *after);
static const char *getvecname(unsigned long vec);
@@ -148,7 +145,6 @@
extern int setjmp(long *);
extern void longjmp(long *, int);
extern unsigned long _ASR;
-extern char SystemCall_common[];

pte_t *find_linux_pte(pgd_t *pgdir, unsigned long va); /* from htab.c */

@@ -488,6 +484,9 @@
if (stepped == 0) {
regs->nip = (unsigned long) &bp->instr[0];
atomic_inc(&bp->ref_count);
+ } else if (stepped < 0) {
+ printf("Couldn't single-step %s instruction\n",
+ (IS_RFID(bp->instr[0])? "rfid": "mtmsrd"));
}
}
}
@@ -755,108 +754,6 @@
set_iabr(0);
}

-static int branch_taken(unsigned int instr, struct pt_regs *regs)
-{
- unsigned int bo = (instr >> 21) & 0x1f;
- unsigned int bi;
-
- if ((bo & 4) == 0) {
- /* decrement counter */
- --regs->ctr;
- if (((bo >> 1) & 1) ^ (regs->ctr == 0))
- return 0;
- }
- if ((bo & 0x10) == 0) {
- /* check bit from CR */
- bi = (instr >> 16) & 0x1f;
- if (((regs->ccr >> (31 - bi)) & 1) != ((bo >> 3) & 1))
- return 0;
- }
- return 1;
-}
-
-/*
- * Emulate instructions that cause a transfer of control.
- * Returns 1 if the step was emulated, 0 if not,
- * or -1 if the instruction is one that should not be stepped,
- * such as an rfid, or a mtmsrd that would clear MSR_RI.
- */
-static int emulate_step(struct pt_regs *regs, unsigned int instr)
-{
- unsigned int opcode, rd;
- unsigned long int imm;
-
- opcode = instr >> 26;
- switch (opcode) {
- case 16: /* bc */
- imm = (signed short)(instr & 0xfffc);
- if ((instr & 2) == 0)
- imm += regs->nip;
- regs->nip += 4; /* XXX check 32-bit mode */
- if (instr & 1)
- regs->link = regs->nip;
- if (branch_taken(instr, regs))
- regs->nip = imm;
- return 1;
- case 17: /* sc */
- regs->gpr[9] = regs->gpr[13];
- regs->gpr[11] = regs->nip + 4;
- regs->gpr[12] = regs->msr & MSR_MASK;
- regs->gpr[13] = (unsigned long) get_paca();
- regs->nip = (unsigned long) &SystemCall_common;
- regs->msr = MSR_KERNEL;
- return 1;
- case 18: /* b */
- imm = instr & 0x03fffffc;
- if (imm & 0x02000000)
- imm -= 0x04000000;
- if ((instr & 2) == 0)
- imm += regs->nip;
- if (instr & 1)
- regs->link = regs->nip + 4;
- regs->nip = imm;
- return 1;
- case 19:
- switch (instr & 0x7fe) {
- case 0x20: /* bclr */
- case 0x420: /* bcctr */
- imm = (instr & 0x400)? regs->ctr: regs->link;
- regs->nip += 4; /* XXX check 32-bit mode */
- if (instr & 1)
- regs->link = regs->nip;
- if (branch_taken(instr, regs))
- regs->nip = imm;
- return 1;
- case 0x24: /* rfid, scary */
- printf("Can't single-step an rfid instruction\n");
- return -1;
- }
- case 31:
- rd = (instr >> 21) & 0x1f;
- switch (instr & 0x7fe) {
- case 0xa6: /* mfmsr */
- regs->gpr[rd] = regs->msr & MSR_MASK;
- regs->nip += 4;
- return 1;
- case 0x164: /* mtmsrd */
- /* only MSR_EE and MSR_RI get changed if bit 15 set */
- /* mtmsrd doesn't change MSR_HV and MSR_ME */
- imm = (instr & 0x10000)? 0x8002: 0xefffffffffffefffUL;
- imm = (regs->msr & MSR_MASK & ~imm)
- | (regs->gpr[rd] & imm);
- if ((imm & MSR_RI) == 0) {
- printf("Can't step an instruction that would "
- "clear MSR.RI\n");
- return -1;
- }
- regs->msr = imm;
- regs->nip += 4;
- return 1;
- }
- }
- return 0;
-}
-
/* Command interpreting routine */
static char *last_cmd;

@@ -988,8 +885,11 @@
if ((regs->msr & (MSR_SF|MSR_PR|MSR_IR)) == (MSR_SF|MSR_IR)) {
if (mread(regs->nip, &instr, 4) == 4) {
stepped = emulate_step(regs, instr);
- if (stepped < 0)
+ if (stepped < 0) {
+ printf("Couldn't single-step %s instruction\n",
+ (IS_RFID(instr)? "rfid": "mtmsrd"));
return 0;
+ }
if (stepped > 0) {
regs->trap = 0xd00 | (regs->trap & 1);
printf("stepped to ");
diff -urN linux-2.5/include/asm-ppc64/sstep.h test/include/asm-ppc64/sstep.h
--- /dev/null 2004-08-12 23:33:25.000000000 +1000
+++ test/include/asm-ppc64/sstep.h 2004-11-18 11:14:59.596330520 +1100
@@ -0,0 +1,13 @@
+/*
+ * Copyright (C) 2004 Paul Mackerras <paulus@xxxxxxxxxx>, IBM
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+struct pt_regs;
+
+/* Emulate instructions that cause a transfer of control. */
+extern int emulate_step(struct pt_regs *regs, unsigned int instr);
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

Next message: John McCutchan: "Re: [patch] inotify: add sysfs store support"
Previous message: Chris Ross: "Re: [PATCH] Remove OOM killer from try_to_free_pages / all_unreclaimablebraindamage"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]