Commit 06fbe81b authored by Christophe Leroy's avatar Christophe Leroy Committed by Michael Ellerman

powerpc/8xx: Add Kernel Userspace Execution Prevention

This patch adds Kernel Userspace Execution Prevention on the 8xx.

When a page is Executable, it is set Executable for Key 0 and NX
for Key 1.

Up to now, the User group is defined with Key 0 for both User and
Supervisor.

By changing the group to Key 0 for User and Key 1 for Supervisor,
this patch prevents the Kernel from being able to execute user code.
Signed-off-by: default avatarChristophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent c341a108
......@@ -41,6 +41,13 @@
*/
#define MI_APG_INIT 0x4fffffff
/*
* 0 => Kernel => 01 (all accesses performed according to page definition)
* 1 => User => 10 (all accesses performed according to swaped page definition)
* 2-16 => NA => 11 (all accesses performed as user iaw page definition)
*/
#define MI_APG_KUEP 0x6fffffff
/* The effective page number register. When read, contains the information
* about the last instruction TLB miss. When MI_RPN is written, bits in
* this register are used to create the TLB entry.
......
......@@ -213,3 +213,15 @@ void flush_instruction_cache(void)
mtspr(SPRN_IC_CST, IDC_INVALL);
isync();
}
#ifdef CONFIG_PPC_KUEP
void __init setup_kuep(bool disabled)
{
if (disabled)
return;
pr_info("Activating Kernel Userspace Execution Prevention\n");
mtspr(SPRN_MI_AP, MI_APG_KUEP);
}
#endif
......@@ -34,6 +34,7 @@ config PPC_8xx
bool "Freescale 8xx"
select FSL_SOC
select SYS_SUPPORTS_HUGETLBFS
select PPC_HAVE_KUEP
config 40x
bool "AMCC 40x"
......
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