| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <51882E6A.6070302@dawncrow.de>
Date: Tue, 07 May 2013 00:27:54 +0200
From: André Hentschel <nerv@...ncrow.de>
To: Jonathan Austin <jonathan.austin@....com>
CC: Russell King - ARM Linux <linux@....linux.org.uk>,
Will Deacon <Will.Deacon@....com>,
"linux-arch@...r.kernel.org" <linux-arch@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCHv2] arm: Preserve TPIDRURW on context switch
Am 03.05.2013 17:24, schrieb Jonathan Austin:
>> - .macro set_tls_none, tp, tmp1, tmp2
>> + .macro switch_tls_none, base, tp, trw, tmp1, tmp2
>> .endm
>>
>> - .macro set_tls_v6k, tp, tmp1, tmp2
>> + .macro switch_tls_v6k, base, tp, trw, tmp1, tmp2
>
> How do you feel about calling tp and trw something different? tpidro
> and tpidrw, or tp and tpuser?
>
> The naming threw me off slightly first time I read this new signature
> (tp=thread_pointer/tls_pointer/etc).
>
FWIW i think tp&tpuser is more consistent.
> André, Assuming I've understood things okay, there's a patch that
> uses Russell's asm stuff (with minor modifications, see the questions)
> and includes the C-world changes too. Perhaps you could see that it
> solves your problem?
It works, but for various reasons i would like to suggest the patch below.
Reasons include: My thoughts about tp&tpuser naming and the helper function for copy_thread, further i'd really like to get a bit credit for spending weeks on getting my second kernel patch in :)
If that patch is fine for you and no one object, i'd be happy to test it, adapt the commit message and include:
Reported-by: André Hentschel <nerv@...ncrow.de>
Signed-off-by: André Hentschel <nerv@...ncrow.de>
Signed-off-by: Will Deacon <will.deacon@....com>
Signed-off-by: Russell King <rmk+kernel@....linux.org.uk>
Signed-off-by: Jonathan Austin <jonathan.austin@....com>
Not totally sure about the Signed-off-bys. Can i add a Signed-off-by for Russell King? Is it the right mail address for him/you?
diff --git a/arch/arm/include/asm/thread_info.h b/arch/arm/include/asm/thread_info.h
index cddda1f..d90be6d 100644
--- a/arch/arm/include/asm/thread_info.h
+++ b/arch/arm/include/asm/thread_info.h
@@ -58,7 +58,7 @@ struct thread_info {
struct cpu_context_save cpu_context; /* cpu context */
__u32 syscall; /* syscall number */
__u8 used_cp[16]; /* thread used copro */
- unsigned long tp_value;
+ unsigned long tp_value[2]; /* TLS registers */
#ifdef CONFIG_CRUNCH
struct crunch_state crunchstate;
#endif
diff --git a/arch/arm/include/asm/tls.h b/arch/arm/include/asm/tls.h
index 73409e6..d7d542b 100644
--- a/arch/arm/include/asm/tls.h
+++ b/arch/arm/include/asm/tls.h
@@ -2,27 +2,30 @@
#define __ASMARM_TLS_H
#ifdef __ASSEMBLY__
- .macro set_tls_none, tp, tmp1, tmp2
+#include <asm/asm-offsets.h>
+ .macro switch_tls_none, base, tp, tpuser, tmp1, tmp2
.endm
- .macro set_tls_v6k, tp, tmp1, tmp2
+ .macro switch_tls_v6k, base, tp, tpuser, tmp1, tmp2
+ mrc p15, 0, \tmp2, c13, c0, 2 @ get the user r/w register
mcr p15, 0, \tp, c13, c0, 3 @ set TLS register
- mov \tmp1, #0
- mcr p15, 0, \tmp1, c13, c0, 2 @ clear user r/w TLS register
+ mcr p15, 0, \tpuser, c13, c0, 2 @ and the user r/w register
+ strne \tmp2, [\base, #TI_TP_VALUE + 4] @ save it
.endm
- .macro set_tls_v6, tp, tmp1, tmp2
+ .macro switch_tls_v6, base, tp, tpuser, tmp1, tmp2
ldr \tmp1, =elf_hwcap
ldr \tmp1, [\tmp1, #0]
mov \tmp2, #0xffff0fff
tst \tmp1, #HWCAP_TLS @ hardware TLS available?
- mcrne p15, 0, \tp, c13, c0, 3 @ yes, set TLS register
- movne \tmp1, #0
- mcrne p15, 0, \tmp1, c13, c0, 2 @ clear user r/w TLS register
streq \tp, [\tmp2, #-15] @ set TLS value at 0xffff0ff0
+ mrcne p15, 0, \tmp2, c13, c0, 2 @ get the user r/w register
+ mcrne p15, 0, \tp, c13, c0, 3 @ yes, set TLS register
+ mcrne p15, 0, \tpuser, c13, c0, 2 @ set user r/w register
+ strne \tmp2, [\base, #TI_TP_VALUE + 4] @ save it
.endm
- .macro set_tls_software, tp, tmp1, tmp2
+ .macro switch_tls_software, base, tp, tpuser, tmp1, tmp2
mov \tmp1, #0xffff0fff
str \tp, [\tmp1, #-15] @ set TLS value at 0xffff0ff0
.endm
@@ -31,19 +34,31 @@
#ifdef CONFIG_TLS_REG_EMUL
#define tls_emu 1
#define has_tls_reg 1
-#define set_tls set_tls_none
+#define switch_tls switch_tls_none
#elif defined(CONFIG_CPU_V6)
#define tls_emu 0
#define has_tls_reg (elf_hwcap & HWCAP_TLS)
-#define set_tls set_tls_v6
+#define switch_tls switch_tls_v6
#elif defined(CONFIG_CPU_32v6K)
#define tls_emu 0
#define has_tls_reg 1
-#define set_tls set_tls_v6k
+#define switch_tls switch_tls_v6k
#else
#define tls_emu 0
#define has_tls_reg 0
-#define set_tls set_tls_software
+#define switch_tls switch_tls_software
#endif
+#ifndef __ASSEMBLY__
+static inline unsigned long get_tlsuser(void)
+{
+ if (has_tls_reg && !tls_emu)
+ {
+ unsigned long t;
+ __asm__("mcr p15, 0, %0, c13, c0, 2" : : "r" (t));
+ return t;
+ }
+ return 0;
+}
+#endif
#endif /* __ASMARM_TLS_H */
diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index 0f82098..80f09fe 100644
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -728,15 +728,15 @@ ENTRY(__switch_to)
UNWIND(.fnstart )
UNWIND(.cantunwind )
add ip, r1, #TI_CPU_SAVE
- ldr r3, [r2, #TI_TP_VALUE]
ARM( stmia ip!, {r4 - sl, fp, sp, lr} ) @ Store most regs on stack
THUMB( stmia ip!, {r4 - sl, fp} ) @ Store most regs on stack
THUMB( str sp, [ip], #4 )
THUMB( str lr, [ip], #4 )
+ ldrd r4, r5, [r2, #TI_TP_VALUE]
#ifdef CONFIG_CPU_USE_DOMAINS
ldr r6, [r2, #TI_CPU_DOMAIN]
#endif
- set_tls r3, r4, r5
+ switch_tls r1, r4, r5, r3, r7
#if defined(CONFIG_CC_STACKPROTECTOR) && !defined(CONFIG_SMP)
ldr r7, [r2, #TI_TASK]
ldr r8, =__stack_chk_guard
diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index 047d3e4..24dbc72 100644
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -39,6 +39,7 @@
#include <asm/thread_notify.h>
#include <asm/stacktrace.h>
#include <asm/mach/time.h>
+#include <asm/tls.h>
#ifdef CONFIG_CC_STACKPROTECTOR
#include <linux/stackprotector.h>
@@ -395,7 +396,8 @@ copy_thread(unsigned long clone_flags, unsigned long stack_start,
clear_ptrace_hw_breakpoint(p);
if (clone_flags & CLONE_SETTLS)
- thread->tp_value = childregs->ARM_r3;
+ thread->tp_value[0] = childregs->ARM_r3;
+ thread->tp_value[1] = get_tlsuser();
thread_notify(THREAD_NOTIFY_COPY, thread);
diff --git a/arch/arm/kernel/ptrace.c b/arch/arm/kernel/ptrace.c
index 03deeff..2bc1514 100644
--- a/arch/arm/kernel/ptrace.c
+++ b/arch/arm/kernel/ptrace.c
@@ -849,7 +849,7 @@ long arch_ptrace(struct task_struct *child, long request,
#endif
case PTRACE_GET_THREAD_AREA:
- ret = put_user(task_thread_info(child)->tp_value,
+ ret = put_user(task_thread_info(child)->tp_value[0],
datap);
break;
diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
index 1c08911..f9d6259 100644
--- a/arch/arm/kernel/traps.c
+++ b/arch/arm/kernel/traps.c
@@ -588,7 +588,7 @@ asmlinkage int arm_syscall(int no, struct pt_regs *regs)
return regs->ARM_r0;
case NR(set_tls):
- thread->tp_value = regs->ARM_r0;
+ thread->tp_value[0] = regs->ARM_r0;
if (tls_emu)
return 0;
if (has_tls_reg) {
@@ -706,7 +706,7 @@ static int get_tp_trap(struct pt_regs *regs, unsigned int instr)
int reg = (instr >> 12) & 15;
if (reg == 15)
return 1;
- regs->uregs[reg] = current_thread_info()->tp_value;
+ regs->uregs[reg] = current_thread_info()->tp_value[0];
regs->ARM_pc += 4;
return 0;
}
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists