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powerpc/44x: Activate KUEP at all time

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On 44x, KUEP is implemented by clearing SX bit during TLB miss
for user pages. The impact is minimal and not worth neither
boot time nor build time selection.

Activate it at all time.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/2414d662558e7fb27d1ed41c8e47c591d576acac.1634627931.git.christophe.leroy@csgroup.eu
This commit is contained in:
Christophe Leroy 2021-10-19 09:29:14 +02:00 committed by Michael Ellerman
parent 13dac4e31e
commit ee2631603f
4 changed files with 4 additions and 16 deletions
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1
arch/powerpc/include/asm/nohash/32/mmu-44x.h
View file

@ -113,7 +113,6 @@ typedef struct {
/* patch sites */
extern s32 patch__tlb_44x_hwater_D, patch__tlb_44x_hwater_I;
extern s32 patch__tlb_44x_kuep, patch__tlb_47x_kuep;
#endif /* !__ASSEMBLY__ */

10
arch/powerpc/kernel/head_44x.S
View file

@ -532,10 +532,7 @@ finish_tlb_load_44x:
andi. r10,r12,_PAGE_USER /* User page ? */
beq 1f /* nope, leave U bits empty */
rlwimi r11,r11,3,26,28 /* yes, copy S bits to U */
#ifdef CONFIG_PPC_KUEP
0: rlwinm r11,r11,0,~PPC44x_TLB_SX /* Clear SX if User page */
patch_site 0b, patch__tlb_44x_kuep
#endif
rlwinm r11,r11,0,~PPC44x_TLB_SX /* Clear SX if User page */
1: tlbwe r11,r13,PPC44x_TLB_ATTRIB /* Write ATTRIB */
/* Done...restore registers and get out of here.
@ -747,10 +744,7 @@ finish_tlb_load_47x:
andi. r10,r12,_PAGE_USER /* User page ? */
beq 1f /* nope, leave U bits empty */
rlwimi r11,r11,3,26,28 /* yes, copy S bits to U */
#ifdef CONFIG_PPC_KUEP
0: rlwinm r11,r11,0,~PPC47x_TLB2_SX /* Clear SX if User page */
patch_site 0b, patch__tlb_47x_kuep
#endif
rlwinm r11,r11,0,~PPC47x_TLB2_SX /* Clear SX if User page */
1: tlbwe r11,r13,2
/* Done...restore registers and get out of here.

8
arch/powerpc/mm/nohash/44x.c
View file

@ -247,12 +247,6 @@ void setup_kuep(bool disabled)
if (smp_processor_id() != boot_cpuid)
return;
if (disabled)
patch_instruction_site(&patch__tlb_44x_kuep, ppc_inst(PPC_RAW_NOP()));
else
pr_info("Activating Kernel Userspace Execution Prevention\n");
if (IS_ENABLED(CONFIG_PPC_47x) && disabled)
patch_instruction_site(&patch__tlb_47x_kuep, ppc_inst(PPC_RAW_NOP()));
pr_info("Activating Kernel Userspace Execution Prevention\n");
}
#endif

1
arch/powerpc/platforms/Kconfig.cputype
View file

@ -63,6 +63,7 @@ config 44x
select HAVE_PCI
select PHYS_64BIT
select PPC_HAVE_KUEP
select PPC_KUEP
endchoice