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Commit e6978e4b authored by Russell King's avatar Russell King
Browse files

ARM: save and reset the address limit when entering an exception 



When we enter an exception, the current address limit should not apply
to the exception context: if the exception context wishes to access
kernel space via the user accessors (eg, perf code), it must explicitly
request such access.

Acked-by: default avatarWill Deacon <will.deacon@arm.com>
Signed-off-by: default avatarRussell King <rmk+kernel@armlinux.org.uk>
parent dd665be0

arch/arm/include/asm/ptrace.h

+1 −1
Original line number Diff line number Diff line
@@ -22,7 +22,7 @@ struct pt_regs { 
struct svc_pt_regs {

	struct pt_regs regs;

	u32 dacr;

	u32 unused;

	u32 addr_limit;

};



#define to_svc_pt_regs(r) container_of(r, struct svc_pt_regs, regs)

arch/arm/kernel/asm-offsets.c

+1 −0
Original line number Diff line number Diff line
@@ -109,6 +109,7 @@ int main(void) 
  DEFINE(S_OLD_R0,		offsetof(struct pt_regs, ARM_ORIG_r0));

  DEFINE(PT_REGS_SIZE,		sizeof(struct pt_regs));

  DEFINE(SVC_DACR,		offsetof(struct svc_pt_regs, dacr));

  DEFINE(SVC_ADDR_LIMIT,	offsetof(struct svc_pt_regs, addr_limit));

  DEFINE(SVC_REGS_SIZE,		sizeof(struct svc_pt_regs));

  BLANK();

#ifdef CONFIG_CACHE_L2X0

arch/arm/kernel/entry-armv.S

+6 −1
Original line number Diff line number Diff line
@@ -185,6 +185,12 @@ ENDPROC(__und_invalid) 
	@

	stmia	r7, {r2 - r6}



	get_thread_info tsk

	ldr	r0, [tsk, #TI_ADDR_LIMIT]

	mov	r1, #TASK_SIZE

	str	r1, [tsk, #TI_ADDR_LIMIT]

	str	r0, [sp, #SVC_ADDR_LIMIT]



	uaccess_save r0

	.if \uaccess

	uaccess_disable r0
@@ -213,7 +219,6 @@ __irq_svc: 
	irq_handler



#ifdef CONFIG_PREEMPT

	get_thread_info tsk

	ldr	r8, [tsk, #TI_PREEMPT]		@ get preempt count

	ldr	r0, [tsk, #TI_FLAGS]		@ get flags

	teq	r8, #0				@ if preempt count != 0

arch/arm/kernel/entry-header.S

+4 −0
Original line number Diff line number Diff line
@@ -215,7 +215,9 @@ 
	blne	trace_hardirqs_off

#endif

	.endif

	ldr	r1, [sp, #SVC_ADDR_LIMIT]

	uaccess_restore

	str	r1, [tsk, #TI_ADDR_LIMIT]



#ifndef CONFIG_THUMB2_KERNEL

	@ ARM mode SVC restore
@@ -259,7 +261,9 @@ 
	@ on the stack remains correct).

	@

	.macro  svc_exit_via_fiq

	ldr	r1, [sp, #SVC_ADDR_LIMIT]

	uaccess_restore

	str	r1, [tsk, #TI_ADDR_LIMIT]

#ifndef CONFIG_THUMB2_KERNEL

	@ ARM mode restore

	mov	r0, sp

arch/arm/kernel/process.c

+8 −4
Original line number Diff line number Diff line
@@ -96,19 +96,23 @@ void __show_regs(struct pt_regs *regs) 
	unsigned long flags;

	char buf[64];

#ifndef CONFIG_CPU_V7M

	unsigned int domain;

	unsigned int domain, fs;

#ifdef CONFIG_CPU_SW_DOMAIN_PAN

	/*

	 * Get the domain register for the parent context. In user

	 * mode, we don't save the DACR, so lets use what it should

	 * be. For other modes, we place it after the pt_regs struct.

	 */

	if (user_mode(regs))

	if (user_mode(regs)) {

		domain = DACR_UACCESS_ENABLE;

	else

		fs = get_fs();

	} else {

		domain = to_svc_pt_regs(regs)->dacr;

		fs = to_svc_pt_regs(regs)->addr_limit;

	}

#else

	domain = get_domain();

	fs = get_fs();

#endif

#endif
@@ -144,7 +148,7 @@ void __show_regs(struct pt_regs *regs) 
		if ((domain & domain_mask(DOMAIN_USER)) ==

		    domain_val(DOMAIN_USER, DOMAIN_NOACCESS))

			segment = "none";

		else if (get_fs() == get_ds())

		else if (fs == get_ds())

			segment = "kernel";

		else

			segment = "user";