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Date: Wed, 04 Dec 2013 19:51:04 +0200
From: Taras Kondratiuk <taras.kondratiuk@...aro.org>
To: David Long <dave.long@...aro.org>,
linux-arm-kernel@...ts.infradead.org,
Russell King <linux@....linux.org.uk>
CC: Rabin Vincent <rabin@....in>,
"Jon Medhurst (Tixy)" <tixy@...aro.org>,
Oleg Nesterov <oleg@...hat.com>,
Srikar Dronamraju <srikar@...ux.vnet.ibm.com>,
Ingo Molnar <mingo@...hat.com>,
Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
Ananth N Mavinakayanahalli <ananth@...ibm.com>,
Anil S Keshavamurthy <anil.s.keshavamurthy@...el.com>,
davem@...emloft.net, Peter Zijlstra <a.p.zijlstra@...llo.nl>,
Paul Mackerras <paulus@...ba.org>,
Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
linux-kernel@...r.kernel.org,
Linaro Networking <linaro-networking@...aro.org>
Subject: Re: [PATCH v3 00/15] uprobes: Add uprobes support for ARM
On 11/27/2013 04:53 AM, David Long wrote:
> From: "David A. Long" <dave.long@...aro.org>
>
> This patch series adds basic uprobes support to ARM. It is based on patches
> developed earlier by Rabin Vincent. That approach of adding hooks into
> the kprobes instruction parsing code was not well received. This approach
> separates the ARM instruction parsing code in kprobes out into a separate set
> of functions which can be used by both kprobes and uprobes. Both kprobes and
> uprobes then provide their own semantic action tables to process the results of
> the parsing.
>
> The following are noteworthy changes made for v3:
>
> 1) The ARM uprobes functionality no longer depends on kprobes. As
> a side effect of this there are no longer any changes to the common
> kprobes include file (or any other common kprobes files).
> 2) A couple large patches have been broken down into more smaller
> patches.
> 3) A problem with uretprobes has been fixed.
> 4) The kprobes-test module has been made more useable for thumb tests.
> 5) The argument list to the "action" functions has been shrunk.
> 6) Alignment with a few recent patches that were made to common
> uprobes code specifically to support this patchset.
>
> This patchset is based on v3.13-rc1
Hi Dave
I've tested this series in big-endian mode.
There is an issue within __create_xol_area() function.
It writes UPROBE_SWBP_INSN directly to memory, but UPROBE_SWBP_INSN
stores canonical opcode, which leads to a wrong instruction endianness
if CPU runs in BE.
I think the easies way to fix it without touching generic uprobes code
is to store opcode in native endianness in UPROBE_SWBP_INSN, and use
another macro for canonical form in ARM specific code.
Please check a diff below. With this diff plus addressed comment for
patch 14/15 plus fixed Ben's BE kprobes series I have uprobes working
on LE and BE.
diff --git a/arch/arm/include/asm/uprobes.h b/arch/arm/include/asm/uprobes.h
index e5acaa3..5313418 100644
--- a/arch/arm/include/asm/uprobes.h
+++ b/arch/arm/include/asm/uprobes.h
@@ -2,14 +2,16 @@
#define _ASM_UPROBES_H
#include <asm/probes.h>
+#include <asm/opcodes.h>
typedef u32 uprobe_opcode_t;
#define MAX_UINSN_BYTES 4
#define UPROBE_XOL_SLOT_BYTES 64
-#define UPROBE_SWBP_INSN 0xe7f001f9
-#define UPROBE_SS_INSN 0xe7f001fa
+#define UPROBE_SWBP_ARM_INSN 0xe7f001f9
+#define UPROBE_SS_ARM_INSN 0xe7f001fa
+#define UPROBE_SWBP_INSN __opcode_to_mem_arm(UPROBE_SWBP_ARM_INSN)
#define UPROBE_SWBP_INSN_SIZE 4
struct arch_uprobe_task {
diff --git a/arch/arm/kernel/uprobes.c b/arch/arm/kernel/uprobes.c
index d9873ef..ae18549 100644
--- a/arch/arm/kernel/uprobes.c
+++ b/arch/arm/kernel/uprobes.c
@@ -22,7 +22,7 @@
bool is_swbp_insn(uprobe_opcode_t *insn)
{
return (__mem_to_opcode_arm(*insn) & 0x0fffffff) ==
- (UPROBE_SWBP_INSN & 0x0fffffff);
+ (UPROBE_SWBP_ARM_INSN & 0x0fffffff);
}
int set_swbp(struct arch_uprobe *auprobe, struct mm_struct *mm,
@@ -83,7 +83,7 @@ int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe, struct mm_struct *mm,
insn = __mem_to_opcode_arm(*(unsigned int *)auprobe->insn);
auprobe->ixol[0] = __opcode_to_mem_arm(insn);
- auprobe->ixol[1] = __opcode_to_mem_arm(UPROBE_SS_INSN);
+ auprobe->ixol[1] = __opcode_to_mem_arm(UPROBE_SS_ARM_INSN);
ret = arm_probes_decode_insn(insn, &auprobe->asi, false,
uprobes_probes_actions);
@@ -100,7 +100,7 @@ int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe, struct mm_struct *mm,
break;
}
- bpinsn = UPROBE_SWBP_INSN & 0x0fffffff;
+ bpinsn = UPROBE_SWBP_ARM_INSN & 0x0fffffff;
if (insn >= 0xe0000000)
bpinsn |= 0xe0000000; /* Unconditional instruction */
else
@@ -158,9 +158,9 @@ static int uprobe_trap_handler(struct pt_regs *regs, unsigned int instr)
local_irq_save(flags);
instr &= 0x0fffffff;
- if (instr == (UPROBE_SWBP_INSN & 0x0fffffff))
+ if (instr == (UPROBE_SWBP_ARM_INSN & 0x0fffffff))
uprobe_pre_sstep_notifier(regs);
- else if (instr == (UPROBE_SS_INSN & 0x0fffffff))
+ else if (instr == (UPROBE_SS_ARM_INSN & 0x0fffffff))
uprobe_post_sstep_notifier(regs);
local_irq_restore(flags);
@@ -174,7 +174,7 @@ unsigned long uprobe_get_swbp_addr(struct pt_regs *regs)
static struct undef_hook uprobes_arm_break_hook = {
.instr_mask = 0x0fffffff,
- .instr_val = (UPROBE_SWBP_INSN & 0x0fffffff),
+ .instr_val = (UPROBE_SWBP_ARM_INSN & 0x0fffffff),
.cpsr_mask = MODE_MASK,
.cpsr_val = USR_MODE,
.fn = uprobe_trap_handler,
@@ -182,7 +182,7 @@ static struct undef_hook uprobes_arm_break_hook = {
static struct undef_hook uprobes_arm_ss_hook = {
.instr_mask = 0x0fffffff,
- .instr_val = (UPROBE_SS_INSN & 0x0fffffff),
+ .instr_val = (UPROBE_SS_ARM_INSN & 0x0fffffff),
.cpsr_mask = MODE_MASK,
.cpsr_val = USR_MODE,
.fn = uprobe_trap_handler,
--
Taras Kondratiuk
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