Currently, only support the kernels where the base of physical memory is at a 16MiB boundary. Because the add/sub instructions only contains 8bits unrotated value. But we can use one more "add/sub" instructions to handle bits 23-16. The performance will be slightly affected.
Since most boards meet 16 MiB alignment, so add a new configuration option ARM_PATCH_PHYS_VIRT_RADICAL (default n) to control it. Say Y if anyone really needs it. All r0-r7 (r1 = machine no, r2 = atags or dtb, in the start-up phase) are used in __fixup_a_pv_table() now, but the callee saved r11 is not used in the whole head.S file. So choose it. Because the calculation of "y = x + __pv_offset[63:24]" have been done, so we only need to calculate "y = y + __pv_offset[23:16]", that's why the parameters "to" and "from" of __pv_stub() and __pv_add_carry_stub() in the scope of CONFIG_ARM_PATCH_PHYS_VIRT_RADICAL are all passed "t" (above y). Signed-off-by: Zhen Lei <thunder.leiz...@huawei.com> --- arch/arm/Kconfig | 18 +++++++++++++++++- arch/arm/include/asm/memory.h | 16 +++++++++++++--- arch/arm/kernel/head.S | 25 +++++++++++++++++++------ 3 files changed, 49 insertions(+), 10 deletions(-) diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index e00d94b16658765..19fc2c746e2ce29 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -240,12 +240,28 @@ config ARM_PATCH_PHYS_VIRT kernel in system memory. This can only be used with non-XIP MMU kernels where the base - of physical memory is at a 16MB boundary. + of physical memory is at a 16MiB boundary. Only disable this option if you know that you do not require this feature (eg, building a kernel for a single machine) and you need to shrink the kernel to the minimal size. +config ARM_PATCH_PHYS_VIRT_RADICAL + bool "Support PHYS_OFFSET minimum aligned at 64KiB boundary" + default n + depends on ARM_PATCH_PHYS_VIRT + depends on !THUMB2_KERNEL + help + This can only be used with non-XIP MMU kernels where the base + of physical memory is at a 64KiB boundary. + + Compared with ARM_PATCH_PHYS_VIRT, one or two more instructions + need to be added to implement the conversion of bits 23-16 of + the VA/PA in phys-to-virt and virt-to-phys. The performance is + slightly affected. + + If unsure say N here. + config NEED_MACH_IO_H bool help diff --git a/arch/arm/include/asm/memory.h b/arch/arm/include/asm/memory.h index 99035b5891ef442..71b3a60eeb1b1c6 100644 --- a/arch/arm/include/asm/memory.h +++ b/arch/arm/include/asm/memory.h @@ -173,6 +173,7 @@ * so that all we need to do is modify the 8-bit constant field. */ #define __PV_BITS_31_24 0x81000000 +#define __PV_BITS_23_16 0x00810000 #define __PV_BITS_7_0 0x81 extern unsigned long __pv_phys_pfn_offset; @@ -201,7 +202,7 @@ : "=r" (t) \ : "I" (__PV_BITS_7_0)) -#define __pv_add_carry_stub(x, y) \ +#define __pv_add_carry_stub(x, y, type) \ __asm__ volatile("@ __pv_add_carry_stub\n" \ "1: adds %Q0, %1, %2\n" \ " adc %R0, %R0, #0\n" \ @@ -209,7 +210,7 @@ " .long 1b\n" \ " .popsection\n" \ : "+r" (y) \ - : "r" (x), "I" (__PV_BITS_31_24) \ + : "r" (x), "I" (type) \ : "cc") static inline phys_addr_t __virt_to_phys_nodebug(unsigned long x) @@ -218,9 +219,15 @@ static inline phys_addr_t __virt_to_phys_nodebug(unsigned long x) if (sizeof(phys_addr_t) == 4) { __pv_stub(x, t, "add", __PV_BITS_31_24); +#ifdef CONFIG_ARM_PATCH_PHYS_VIRT_RADICAL + __pv_stub(t, t, "add", __PV_BITS_23_16); +#endif } else { __pv_stub_mov_hi(t); - __pv_add_carry_stub(x, t); + __pv_add_carry_stub(x, t, __PV_BITS_31_24); +#ifdef CONFIG_ARM_PATCH_PHYS_VIRT_RADICAL + __pv_add_carry_stub(t, t, __PV_BITS_23_16); +#endif } return t; } @@ -236,6 +243,9 @@ static inline unsigned long __phys_to_virt(phys_addr_t x) * in place where 'r' 32 bit operand is expected. */ __pv_stub((unsigned long) x, t, "sub", __PV_BITS_31_24); +#ifdef CONFIG_ARM_PATCH_PHYS_VIRT_RADICAL + __pv_stub((unsigned long) t, t, "sub", __PV_BITS_23_16); +#endif return t; } diff --git a/arch/arm/kernel/head.S b/arch/arm/kernel/head.S index 02d78c9198d0e8d..d9fb226a24d43ae 100644 --- a/arch/arm/kernel/head.S +++ b/arch/arm/kernel/head.S @@ -120,7 +120,7 @@ ENTRY(stext) bl __fixup_smp #endif #ifdef CONFIG_ARM_PATCH_PHYS_VIRT - bl __fixup_pv_table + bl __fixup_pv_table @r11 will be used #endif bl __create_page_tables @@ -614,8 +614,13 @@ __fixup_pv_table: mov r0, r8, lsr #PAGE_SHIFT @ convert to PFN str r0, [r6] @ save computed PHYS_PFN_OFFSET to __pv_phys_pfn_offset strcc ip, [r7, #HIGH_OFFSET] @ save to __pv_offset high bits +#ifdef CONFIG_ARM_PATCH_PHYS_VIRT_RADICAL + mov r6, r3, lsr #16 @ constant for add/sub instructions + teq r3, r6, lsl #16 @ must be 64KiB aligned +#else mov r6, r3, lsr #24 @ constant for add/sub instructions teq r3, r6, lsl #24 @ must be 16MiB aligned +#endif THUMB( it ne @ cross section branch ) bne __error str r3, [r7, #LOW_OFFSET] @ save to __pv_offset low bits @@ -636,7 +641,9 @@ __fixup_a_pv_table: add r6, r6, r3 ldr r0, [r6, #HIGH_OFFSET] @ __pv_offset high word ldr r6, [r6, #LOW_OFFSET] @ __pv_offset low word - mov r6, r6, lsr #24 + mov r11, r6, lsl #8 + mov r11, r11, lsr #24 @ bits 23-16 + mov r6, r6, lsr #24 @ bits 31-24 cmn r0, #1 #ifdef CONFIG_THUMB2_KERNEL moveq r0, #0x200000 @ set bit 21, mov to mvn instruction @@ -682,14 +689,20 @@ ARM_BE8(rev16 ip, ip) #ifdef CONFIG_CPU_ENDIAN_BE8 @ in BE8, we load data in BE, but instructions still in LE bic ip, ip, #0xff000000 - tst ip, #0x000f0000 @ check the rotation field + tst ip, #0x00040000 @ check the rotation field orrne ip, ip, r6, lsl #24 @ mask in offset bits 31-24 + tst ip, #0x00080000 @ check the rotation field + orrne ip, ip, r11, lsl #24 @ mask in offset bits 23-16 + tst ip, #0x000f0000 @ check the rotation field biceq ip, ip, #0x00004000 @ clear bit 22 orreq ip, ip, r0 @ mask in offset bits 7-0 #else bic ip, ip, #0x000000ff - tst ip, #0xf00 @ check the rotation field + tst ip, #0x400 @ check the rotation field orrne ip, ip, r6 @ mask in offset bits 31-24 + tst ip, #0x800 @ check the rotation field + orrne ip, ip, r11 @ mask in offset bits 23-16 + tst ip, #0xf00 @ check the rotation field biceq ip, ip, #0x400000 @ clear bit 22 orreq ip, ip, r0 @ mask in offset bits 7-0 #endif @@ -705,12 +718,12 @@ ENDPROC(__fixup_a_pv_table) 3: .long __pv_offset ENTRY(fixup_pv_table) - stmfd sp!, {r4 - r7, lr} + stmfd sp!, {r4 - r7, r11, lr} mov r3, #0 @ no offset mov r4, r0 @ r0 = table start add r5, r0, r1 @ r1 = table size bl __fixup_a_pv_table - ldmfd sp!, {r4 - r7, pc} + ldmfd sp!, {r4 - r7, r11, pc} ENDPROC(fixup_pv_table) .data -- 1.8.3