From a2b45b0da8bbb98cb2f062cf16c6fdebab4243a1 Mon Sep 17 00:00:00 2001 From: Jonathan Austin Date: Thu, 21 Feb 2013 17:49:24 +0000 Subject: ARM: mpu: add header for MPU register layouts and region data This commit adds definitions relevant to the ARM v7 PMSA compliant MPU. The register layouts and region configuration data is made accessible to asm as well as C-code so that it can be used in early bring-up of the MPU. The mpu region information structs assume that the properties for the I/D side are the same, though the implementation could be trivially extended for future platforms where this is no-longer true. The MPU_*_REGION defines are used for the basic, static MPU region setup. Signed-off-by: Jonathan Austin Reviewed-by: Will Deacon --- arch/arm/include/asm/mpu.h | 72 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 72 insertions(+) create mode 100644 arch/arm/include/asm/mpu.h (limited to 'arch/arm/include/asm/mpu.h') diff --git a/arch/arm/include/asm/mpu.h b/arch/arm/include/asm/mpu.h new file mode 100644 index 00000000000..bd48c0cb544 --- /dev/null +++ b/arch/arm/include/asm/mpu.h @@ -0,0 +1,72 @@ +#ifndef __ARM_MPU_H +#define __ARM_MPU_H + +#ifdef CONFIG_ARM_MPU + +/* MPUIR layout */ +#define MPUIR_nU 1 +#define MPUIR_DREGION 8 +#define MPUIR_IREGION 16 +#define MPUIR_DREGION_SZMASK (0xFF << MPUIR_DREGION) +#define MPUIR_IREGION_SZMASK (0xFF << MPUIR_IREGION) + +/* ID_MMFR0 data relevant to MPU */ +#define MMFR0_PMSA (0xF << 4) +#define MMFR0_PMSAv7 (3 << 4) + +/* MPU D/I Size Register fields */ +#define MPU_RSR_SZ 1 +#define MPU_RSR_EN 0 + +/* The D/I RSR value for an enabled region spanning the whole of memory */ +#define MPU_RSR_ALL_MEM 63 + +/* Individual bits in the DR/IR ACR */ +#define MPU_ACR_XN (1 << 12) +#define MPU_ACR_SHARED (1 << 2) + +/* C, B and TEX[2:0] bits only have semantic meanings when grouped */ +#define MPU_RGN_CACHEABLE 0xB +#define MPU_RGN_SHARED_CACHEABLE (MPU_RGN_CACHEABLE | MPU_ACR_SHARED) +#define MPU_RGN_STRONGLY_ORDERED 0 + +/* Main region should only be shared for SMP */ +#ifdef CONFIG_SMP +#define MPU_RGN_NORMAL (MPU_RGN_CACHEABLE | MPU_ACR_SHARED) +#else +#define MPU_RGN_NORMAL MPU_RGN_CACHEABLE +#endif + +/* Access permission bits of ACR (only define those that we use)*/ +#define MPU_AP_PL1RW_PL0RW (0x3 << 8) +#define MPU_AP_PL1RW_PL0R0 (0x2 << 8) +#define MPU_AP_PL1RW_PL0NA (0x1 << 8) + +/* For minimal static MPU region configurations */ +#define MPU_PROBE_REGION 0 +#define MPU_BG_REGION 1 +#define MPU_RAM_REGION 2 + +/* Maximum number of regions Linux is interested in */ +#define MPU_MAX_REGIONS 16 + +#ifndef __ASSEMBLY__ + +struct mpu_rgn { + /* Assume same attributes for d/i-side */ + u32 drbar; + u32 drsr; + u32 dracr; +}; + +struct mpu_rgn_info { + u32 mpuir; + struct mpu_rgn rgns[MPU_MAX_REGIONS]; +}; +extern struct mpu_rgn_info mpu_rgn_info; + +#endif /* __ASSEMBLY__ */ + +#endif /* CONFIG_ARM_MPU */ + +#endif -- cgit v1.2.3-70-g09d2 From 67c9845beab16a0c97b9c07f72a4b36b7175bb86 Mon Sep 17 00:00:00 2001 From: Jonathan Austin Date: Fri, 22 Feb 2013 17:48:56 +0000 Subject: ARM: mpu: add early bring-up code for the ARMv7 PMSA-compliant MPU This patch adds initial support for using the MPU, which is necessary for SMP operation on PMSAv7 processors because it is the only way to ensure memory is shared. This is an initial patch and full SMP support is added later in this series. The setup of the MPU is performed in a way analagous to that for the MMU: Very early initialisation before the C environment is brought up, followed by a sanity check and more complete initialisation in C. This patch provides the simplest possible memory region configuration: MPU_PROBE_REGION: Reserved for probing MPU details, not enabled MPU_BG_REGION: A 'background' region that specifies all memory strongly ordered MPU_RAM_REGION: A single shared, cacheable, normal region for the valid RAM. In this early initialisation code we simply map the whole of the address space with the BG_REGION and (at least) the kernel with the RAM_REGION. The MPU has region alignment constraints that require us to round past the end of the kernel. As region 2 has a higher priority than region 1, it overrides the strongly- ordered behaviour for RAM only. Subsequent patches will add more complete initialisation from the C-world and support for bringing up secondary CPUs. Signed-off-by: Jonathan Austin Reviewed-by: Will Deacon CC: Hyok S. Choi --- arch/arm/include/asm/mpu.h | 3 ++ arch/arm/kernel/head-nommu.S | 87 ++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 90 insertions(+) (limited to 'arch/arm/include/asm/mpu.h') diff --git a/arch/arm/include/asm/mpu.h b/arch/arm/include/asm/mpu.h index bd48c0cb544..001483465aa 100644 --- a/arch/arm/include/asm/mpu.h +++ b/arch/arm/include/asm/mpu.h @@ -50,6 +50,9 @@ /* Maximum number of regions Linux is interested in */ #define MPU_MAX_REGIONS 16 +#define MPU_DATA_SIDE 0 +#define MPU_INSTR_SIDE 1 + #ifndef __ASSEMBLY__ struct mpu_rgn { diff --git a/arch/arm/kernel/head-nommu.S b/arch/arm/kernel/head-nommu.S index 06ba9c8e62b..659912c4957 100644 --- a/arch/arm/kernel/head-nommu.S +++ b/arch/arm/kernel/head-nommu.S @@ -17,9 +17,11 @@ #include #include #include +#include #include #include #include +#include /* * Kernel startup entry point. @@ -63,6 +65,17 @@ ENTRY(stext) movs r10, r5 @ invalid processor (r5=0)? beq __error_p @ yes, error 'p' +#ifdef CONFIG_ARM_MPU + /* Calculate the size of a region covering just the kernel */ + ldr r5, =PHYS_OFFSET @ Region start: PHYS_OFFSET + ldr r6, =(_end) @ Cover whole kernel + sub r6, r6, r5 @ Minimum size of region to map + clz r6, r6 @ Region size must be 2^N... + rsb r6, r6, #31 @ ...so round up region size + lsl r6, r6, #MPU_RSR_SZ @ Put size in right field + orr r6, r6, #(1 << MPU_RSR_EN) @ Set region enabled bit + bl __setup_mpu +#endif ldr r13, =__mmap_switched @ address to jump to after @ initialising sctlr adr lr, BSYM(1f) @ return (PIC) address @@ -147,4 +160,78 @@ __after_proc_init: ENDPROC(__after_proc_init) .ltorg +#ifdef CONFIG_ARM_MPU + + +/* Set which MPU region should be programmed */ +.macro set_region_nr tmp, rgnr + mov \tmp, \rgnr @ Use static region numbers + mcr p15, 0, \tmp, c6, c2, 0 @ Write RGNR +.endm + +/* Setup a single MPU region, either D or I side (D-side for unified) */ +.macro setup_region bar, acr, sr, side = MPU_DATA_SIDE + mcr p15, 0, \bar, c6, c1, (0 + \side) @ I/DRBAR + mcr p15, 0, \acr, c6, c1, (4 + \side) @ I/DRACR + mcr p15, 0, \sr, c6, c1, (2 + \side) @ I/DRSR +.endm + +/* + * Setup the MPU and initial MPU Regions. We create the following regions: + * Region 0: Use this for probing the MPU details, so leave disabled. + * Region 1: Background region - covers the whole of RAM as strongly ordered + * Region 2: Normal, Shared, cacheable for RAM. From PHYS_OFFSET, size from r6 + * + * r6: Value to be written to DRSR (and IRSR if required) for MPU_RAM_REGION +*/ + +ENTRY(__setup_mpu) + + /* Probe for v7 PMSA compliance */ + mrc p15, 0, r0, c0, c1, 4 @ Read ID_MMFR0 + and r0, r0, #(MMFR0_PMSA) @ PMSA field + teq r0, #(MMFR0_PMSAv7) @ PMSA v7 + bne __error_p @ Fail: ARM_MPU on NOT v7 PMSA + + /* Determine whether the D/I-side memory map is unified. We set the + * flags here and continue to use them for the rest of this function */ + mrc p15, 0, r0, c0, c0, 4 @ MPUIR + ands r5, r0, #MPUIR_DREGION_SZMASK @ 0 size d region => No MPU + beq __error_p @ Fail: ARM_MPU and no MPU + tst r0, #MPUIR_nU @ MPUIR_nU = 0 for unified + + /* Setup second region first to free up r6 */ + set_region_nr r0, #MPU_RAM_REGION + isb + /* Full access from PL0, PL1, shared for CONFIG_SMP, cacheable */ + ldr r0, =PHYS_OFFSET @ RAM starts at PHYS_OFFSET + ldr r5,=(MPU_AP_PL1RW_PL0RW | MPU_RGN_NORMAL) + + setup_region r0, r5, r6, MPU_DATA_SIDE @ PHYS_OFFSET, shared, enabled + beq 1f @ Memory-map not unified + setup_region r0, r5, r6, MPU_INSTR_SIDE @ PHYS_OFFSET, shared, enabled +1: isb + + /* First/background region */ + set_region_nr r0, #MPU_BG_REGION + isb + /* Execute Never, strongly ordered, inaccessible to PL0, rw PL1 */ + mov r0, #0 @ BG region starts at 0x0 + ldr r5,=(MPU_ACR_XN | MPU_RGN_STRONGLY_ORDERED | MPU_AP_PL1RW_PL0NA) + mov r6, #MPU_RSR_ALL_MEM @ 4GB region, enabled + + setup_region r0, r5, r6, MPU_DATA_SIDE @ 0x0, BG region, enabled + beq 2f @ Memory-map not unified + setup_region r0, r5, r6, MPU_INSTR_SIDE @ 0x0, BG region, enabled +2: isb + + /* Enable the MPU */ + mrc p15, 0, r0, c1, c0, 0 @ Read SCTLR + bic r0, r0, #CR_BR @ Disable the 'default mem-map' + orr r0, r0, #CR_M @ Set SCTRL.M (MPU on) + mcr p15, 0, r0, c1, c0, 0 @ Enable MPU + isb + mov pc,lr +ENDPROC(__setup_mpu) +#endif #include "head-common.S" -- cgit v1.2.3-70-g09d2 From 9dfc28b6308096e48b54c28259825a1200f60742 Mon Sep 17 00:00:00 2001 From: Jonathan Austin Date: Thu, 18 Apr 2013 18:37:24 +0100 Subject: ARM: mpu: protect the vectors page with an MPU region Without an MMU it is possible for userspace programs to start executing code in places that they have no business executing. The MPU allows some level of protection against this. This patch protects the vectors page from access by userspace processes. Userspace tasks that dereference a null pointer are already protected by an svc at 0x0 that kills them. However when tasks use an offset from a null pointer (eg a function in a null struct) they miss this carefully placed svc and enter the exception vectors in user mode, ending up in the kernel. This patch causes programs that do this to receive a SEGV instead of happily entering the kernel in user-mode, and hence avoid a 'Bad Mode' panic. As part of this change it is necessary to make sigreturn happen via the stack when there is not an sa_restorer function. This change is invisible to userspace, and irrelevant to code compiled using a uClibc toolchain, which always uses an sa_restorer function. Because we don't get to remap the vectors in !MMU kuser_helpers are not in a defined location, and hence aren't usable. This means we don't need to worry about keeping them accessible from PL0 Signed-off-by: Jonathan Austin Reviewed-by: Will Deacon CC: Nicolas Pitre CC: Catalin Marinas --- arch/arm/include/asm/mpu.h | 1 + arch/arm/kernel/head-nommu.S | 16 ++++++++++++++++ arch/arm/kernel/signal.c | 9 +++++++-- 3 files changed, 24 insertions(+), 2 deletions(-) (limited to 'arch/arm/include/asm/mpu.h') diff --git a/arch/arm/include/asm/mpu.h b/arch/arm/include/asm/mpu.h index 001483465aa..c3247cc2fe0 100644 --- a/arch/arm/include/asm/mpu.h +++ b/arch/arm/include/asm/mpu.h @@ -46,6 +46,7 @@ #define MPU_PROBE_REGION 0 #define MPU_BG_REGION 1 #define MPU_RAM_REGION 2 +#define MPU_VECTORS_REGION 3 /* Maximum number of regions Linux is interested in */ #define MPU_MAX_REGIONS 16 diff --git a/arch/arm/kernel/head-nommu.S b/arch/arm/kernel/head-nommu.S index 13741d004de..75f14cc3e07 100644 --- a/arch/arm/kernel/head-nommu.S +++ b/arch/arm/kernel/head-nommu.S @@ -22,6 +22,7 @@ #include #include #include +#include /* * Kernel startup entry point. @@ -188,6 +189,7 @@ ENDPROC(__after_proc_init) * Region 0: Use this for probing the MPU details, so leave disabled. * Region 1: Background region - covers the whole of RAM as strongly ordered * Region 2: Normal, Shared, cacheable for RAM. From PHYS_OFFSET, size from r6 + * Region 3: Normal, shared, inaccessible from PL0 to protect the vectors page * * r6: Value to be written to DRSR (and IRSR if required) for MPU_RAM_REGION */ @@ -232,6 +234,20 @@ ENTRY(__setup_mpu) setup_region r0, r5, r6, MPU_INSTR_SIDE @ 0x0, BG region, enabled 2: isb + /* Vectors region */ + set_region_nr r0, #MPU_VECTORS_REGION + isb + /* Shared, inaccessible to PL0, rw PL1 */ + mov r0, #CONFIG_VECTORS_BASE @ Cover from VECTORS_BASE + ldr r5,=(MPU_AP_PL1RW_PL0NA | MPU_RGN_NORMAL) + /* Writing N to bits 5:1 (RSR_SZ) --> region size 2^N+1 */ + mov r6, #(((PAGE_SHIFT - 1) << MPU_RSR_SZ) | 1 << MPU_RSR_EN) + + setup_region r0, r5, r6, MPU_DATA_SIDE @ VECTORS_BASE, PL0 NA, enabled + beq 3f @ Memory-map not unified + setup_region r0, r5, r6, MPU_INSTR_SIDE @ VECTORS_BASE, PL0 NA, enabled +3: isb + /* Enable the MPU */ mrc p15, 0, r0, c1, c0, 0 @ Read SCTLR bic r0, r0, #CR_BR @ Disable the 'default mem-map' diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c index 296786bdbb7..1c16c35c271 100644 --- a/arch/arm/kernel/signal.c +++ b/arch/arm/kernel/signal.c @@ -392,14 +392,19 @@ setup_return(struct pt_regs *regs, struct ksignal *ksig, if (ksig->ka.sa.sa_flags & SA_SIGINFO) idx += 3; + /* + * Put the sigreturn code on the stack no matter which return + * mechanism we use in order to remain ABI compliant + */ if (__put_user(sigreturn_codes[idx], rc) || __put_user(sigreturn_codes[idx+1], rc+1)) return 1; - if (cpsr & MODE32_BIT) { + if ((cpsr & MODE32_BIT) && !IS_ENABLED(CONFIG_ARM_MPU)) { /* * 32-bit code can use the new high-page - * signal return code support. + * signal return code support except when the MPU has + * protected the vectors page from PL0 */ retcode = KERN_SIGRETURN_CODE + (idx << 2) + thumb; } else { -- cgit v1.2.3-70-g09d2