From 06bff6b9d7d50566a9320f64b0624957798cb08b Mon Sep 17 00:00:00 2001 From: Helge Deller Date: Sat, 9 Apr 2016 08:26:14 +0200 Subject: [PATCH] parisc: Simplify and speed up get_user() and put_user() This patch simplifies the code for get_user() and put_user() a lot. Instead of accessing kernel memory (%sr0) and userspace memory (%sr3) hard-coded in the assembler instruction, we now preload %sr2 with either %sr0 (for accessing KERNEL_DS) or with sr3 (to access USER_DS) and use %sr2 in the load directly. The generated code avoids a branch and speeds up execution by generating less assembler instructions. Signed-off-by: Helge Deller Tested-by: Rolf Eike Beer --- arch/parisc/include/asm/uaccess.h | 79 ++++++++----------------------- 1 file changed, 21 insertions(+), 58 deletions(-) diff --git a/arch/parisc/include/asm/uaccess.h b/arch/parisc/include/asm/uaccess.h index 7955e43f3f3f..56b7208da9a4 100644 --- a/arch/parisc/include/asm/uaccess.h +++ b/arch/parisc/include/asm/uaccess.h @@ -40,14 +40,10 @@ static inline long access_ok(int type, const void __user * addr, #define get_user __get_user #if !defined(CONFIG_64BIT) -#define LDD_KERNEL(ptr) BUILD_BUG() #define LDD_USER(ptr) BUILD_BUG() -#define STD_KERNEL(x, ptr) __put_kernel_asm64(x, ptr) #define STD_USER(x, ptr) __put_user_asm64(x, ptr) #else -#define LDD_KERNEL(ptr) __get_kernel_asm("ldd", ptr) #define LDD_USER(ptr) __get_user_asm("ldd", ptr) -#define STD_KERNEL(x, ptr) __put_kernel_asm("std", x, ptr) #define STD_USER(x, ptr) __put_user_asm("std", x, ptr) #endif @@ -80,43 +76,39 @@ struct exception_data { unsigned long fault_addr; }; +/* + * load_sr2() preloads the space register %%sr2 - based on the value of + * get_fs() - with either a value of 0 to access kernel space (KERNEL_DS which + * is 0), or with the current value of %%sr3 to access user space (USER_DS) + * memory. The following __get_user_asm() and __put_user_asm() functions have + * %%sr2 hard-coded to access the requested memory. + */ +#define load_sr2() \ + __asm__(" or,= %0,%%r0,%%r0\n\t" \ + " mfsp %%sr3,%0\n\t" \ + " mtsp %0,%%sr2\n\t" \ + : : "r"(get_fs()) : ) + #define __get_user(x, ptr) \ ({ \ register long __gu_err __asm__ ("r8") = 0; \ register long __gu_val __asm__ ("r9") = 0; \ \ - if (segment_eq(get_fs(), KERNEL_DS)) { \ - switch (sizeof(*(ptr))) { \ - case 1: __get_kernel_asm("ldb", ptr); break; \ - case 2: __get_kernel_asm("ldh", ptr); break; \ - case 4: __get_kernel_asm("ldw", ptr); break; \ - case 8: LDD_KERNEL(ptr); break; \ - default: BUILD_BUG(); break; \ - } \ - } \ - else { \ - switch (sizeof(*(ptr))) { \ + load_sr2(); \ + switch (sizeof(*(ptr))) { \ case 1: __get_user_asm("ldb", ptr); break; \ case 2: __get_user_asm("ldh", ptr); break; \ case 4: __get_user_asm("ldw", ptr); break; \ case 8: LDD_USER(ptr); break; \ default: BUILD_BUG(); break; \ - } \ } \ \ (x) = (__force __typeof__(*(ptr))) __gu_val; \ __gu_err; \ }) -#define __get_kernel_asm(ldx, ptr) \ - __asm__("\n1:\t" ldx "\t0(%2),%0\n\t" \ - ASM_EXCEPTIONTABLE_ENTRY(1b, fixup_get_user_skip_1)\ - : "=r"(__gu_val), "=r"(__gu_err) \ - : "r"(ptr), "1"(__gu_err) \ - : "r1"); - #define __get_user_asm(ldx, ptr) \ - __asm__("\n1:\t" ldx "\t0(%%sr3,%2),%0\n\t" \ + __asm__("\n1:\t" ldx "\t0(%%sr2,%2),%0\n\t" \ ASM_EXCEPTIONTABLE_ENTRY(1b, fixup_get_user_skip_1)\ : "=r"(__gu_val), "=r"(__gu_err) \ : "r"(ptr), "1"(__gu_err) \ @@ -127,23 +119,13 @@ struct exception_data { register long __pu_err __asm__ ("r8") = 0; \ __typeof__(*(ptr)) __x = (__typeof__(*(ptr)))(x); \ \ - if (segment_eq(get_fs(), KERNEL_DS)) { \ - switch (sizeof(*(ptr))) { \ - case 1: __put_kernel_asm("stb", __x, ptr); break; \ - case 2: __put_kernel_asm("sth", __x, ptr); break; \ - case 4: __put_kernel_asm("stw", __x, ptr); break; \ - case 8: STD_KERNEL(__x, ptr); break; \ - default: BUILD_BUG(); break; \ - } \ - } \ - else { \ - switch (sizeof(*(ptr))) { \ + load_sr2(); \ + switch (sizeof(*(ptr))) { \ case 1: __put_user_asm("stb", __x, ptr); break; \ case 2: __put_user_asm("sth", __x, ptr); break; \ case 4: __put_user_asm("stw", __x, ptr); break; \ case 8: STD_USER(__x, ptr); break; \ default: BUILD_BUG(); break; \ - } \ } \ \ __pu_err; \ @@ -159,17 +141,9 @@ struct exception_data { * r8/r9 are already listed as err/val. */ -#define __put_kernel_asm(stx, x, ptr) \ - __asm__ __volatile__ ( \ - "\n1:\t" stx "\t%2,0(%1)\n\t" \ - ASM_EXCEPTIONTABLE_ENTRY(1b, fixup_put_user_skip_1)\ - : "=r"(__pu_err) \ - : "r"(ptr), "r"(x), "0"(__pu_err) \ - : "r1") - #define __put_user_asm(stx, x, ptr) \ __asm__ __volatile__ ( \ - "\n1:\t" stx "\t%2,0(%%sr3,%1)\n\t" \ + "\n1:\t" stx "\t%2,0(%%sr2,%1)\n\t" \ ASM_EXCEPTIONTABLE_ENTRY(1b, fixup_put_user_skip_1)\ : "=r"(__pu_err) \ : "r"(ptr), "r"(x), "0"(__pu_err) \ @@ -178,21 +152,10 @@ struct exception_data { #if !defined(CONFIG_64BIT) -#define __put_kernel_asm64(__val, ptr) do { \ - __asm__ __volatile__ ( \ - "\n1:\tstw %2,0(%1)" \ - "\n2:\tstw %R2,4(%1)\n\t" \ - ASM_EXCEPTIONTABLE_ENTRY(1b, fixup_put_user_skip_2)\ - ASM_EXCEPTIONTABLE_ENTRY(2b, fixup_put_user_skip_1)\ - : "=r"(__pu_err) \ - : "r"(ptr), "r"(__val), "0"(__pu_err) \ - : "r1"); \ -} while (0) - #define __put_user_asm64(__val, ptr) do { \ __asm__ __volatile__ ( \ - "\n1:\tstw %2,0(%%sr3,%1)" \ - "\n2:\tstw %R2,4(%%sr3,%1)\n\t" \ + "\n1:\tstw %2,0(%%sr2,%1)" \ + "\n2:\tstw %R2,4(%%sr2,%1)\n\t" \ ASM_EXCEPTIONTABLE_ENTRY(1b, fixup_put_user_skip_2)\ ASM_EXCEPTIONTABLE_ENTRY(2b, fixup_put_user_skip_1)\ : "=r"(__pu_err) \ -- 2.20.1