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| author |   Christophe Leroy <christophe.leroy@csgroup.eu> | 2021-06-02 06:42:10 +0000 |
|---|---|---|
| committer |   Michael Ellerman <mpe@ellerman.id.au> | 2021-06-17 00:09:07 +1000 |
| commit | 10248dcba1205042a3a0ea65eb441030702d97cd (patch) | |
| tree | 47e29ca6d4f4828409d3c64d9a4f5493d13608fa | |
| parent | powerpc: Remove CONFIG_PPC_MMU_NOHASH_32 (diff) | |
| download | linux-dev-10248dcba1205042a3a0ea65eb441030702d97cd.tar.xz linux-dev-10248dcba1205042a3a0ea65eb441030702d97cd.zip | |
powerpc/44x: Implement Kernel Userspace Exec Protection (KUEP)
Powerpc 44x has two bits for exec protection in TLBs: one
for user (UX) and one for superviser (SX).
Clear SX on user pages in TLB miss handlers to provide KUEP.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/169310e08152aa1d96c979770291d165ec6896ae.1622616032.git.christophe.leroy@csgroup.eu
| -rw-r--r-- | arch/powerpc/include/asm/nohash/32/mmu-44x.h | 1 | ||||
| -rw-r--r-- | arch/powerpc/kernel/head_44x.S | 8 | ||||
| -rw-r--r-- | arch/powerpc/mm/nohash/44x.c | 13 | ||||
| -rw-r--r-- | arch/powerpc/platforms/Kconfig.cputype | 1 |
4 files changed, 23 insertions, 0 deletions
diff --git a/arch/powerpc/include/asm/nohash/32/mmu-44x.h b/arch/powerpc/include/asm/nohash/32/mmu-44x.h index 2d92a39d8f2e..43ceca128531 100644 --- a/arch/powerpc/include/asm/nohash/32/mmu-44x.h +++ b/arch/powerpc/include/asm/nohash/32/mmu-44x.h @@ -113,6 +113,7 @@ 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__ */ diff --git a/arch/powerpc/kernel/head_44x.S b/arch/powerpc/kernel/head_44x.S index 5c106ac36626..2cfb496df615 100644 --- a/arch/powerpc/kernel/head_44x.S +++ b/arch/powerpc/kernel/head_44x.S @@ -532,6 +532,10 @@ 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 1: tlbwe r11,r13,PPC44x_TLB_ATTRIB /* Write ATTRIB */ /* Done...restore registers and get out of here. @@ -743,6 +747,10 @@ 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 1: tlbwe r11,r13,2 /* Done...restore registers and get out of here. diff --git a/arch/powerpc/mm/nohash/44x.c b/arch/powerpc/mm/nohash/44x.c index 3d6ae7c72412..7da6d1e9fc9b 100644 --- a/arch/powerpc/mm/nohash/44x.c +++ b/arch/powerpc/mm/nohash/44x.c @@ -239,3 +239,16 @@ void __init mmu_init_secondary(int cpu) } } #endif /* CONFIG_SMP */ + +#ifdef CONFIG_PPC_KUEP +void __init setup_kuep(bool disabled) +{ + 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())); +} +#endif diff --git a/arch/powerpc/platforms/Kconfig.cputype b/arch/powerpc/platforms/Kconfig.cputype index dc7c46f92302..d4acba7551c2 100644 --- a/arch/powerpc/platforms/Kconfig.cputype +++ b/arch/powerpc/platforms/Kconfig.cputype @@ -61,6 +61,7 @@ config 44x select 4xx_SOC select HAVE_PCI select PHYS_64BIT + select PPC_HAVE_KUEP endchoice |