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

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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: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
This commit is contained in:
Russell King 2016-05-13 11:40:20 +01:00
parent dd665be0e2
commit e6978e4bf1
5 changed files with 20 additions and 6 deletions
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12
arch/arm/kernel/process.c
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@ -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";