Messages in this thread Patch in this message | | | Date | Fri, 05 Nov 2021 18:10:42 +0100 | From | Peter Zijlstra <> | Subject | [PATCH 19/22] x86,usercopy: Remove .fixup usage |
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Typically usercopy does whole word copies followed by a number of byte copies to finish the tail. This means that on exception it needs to compute the remaining length as: words*sizeof(long) + bytes.
Create a new extable handler to do just this.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> --- arch/x86/include/asm/extable_fixup_types.h | 5 +++++ arch/x86/lib/usercopy_32.c | 28 +++++----------------------- arch/x86/lib/usercopy_64.c | 8 +++----- arch/x86/mm/extable.c | 9 +++++++++ 4 files changed, 22 insertions(+), 28 deletions(-)
--- a/arch/x86/include/asm/extable_fixup_types.h +++ b/arch/x86/include/asm/extable_fixup_types.h @@ -46,4 +46,9 @@ #define EX_TYPE_FAULT_SGX 18 +#define EX_TYPE_UCOPY_LEN 19 /* cx := reg + imm*cx */ +#define EX_TYPE_UCOPY_LEN1 (EX_TYPE_UCOPY_LEN | EX_DATA_IMM(1)) +#define EX_TYPE_UCOPY_LEN4 (EX_TYPE_UCOPY_LEN | EX_DATA_IMM(4)) +#define EX_TYPE_UCOPY_LEN8 (EX_TYPE_UCOPY_LEN | EX_DATA_IMM(8)) + #endif --- a/arch/x86/lib/usercopy_32.c +++ b/arch/x86/lib/usercopy_32.c @@ -43,11 +43,7 @@ do { \ " movl %2,%0\n" \ "1: rep; stosb\n" \ "2: " ASM_CLAC "\n" \ - ".section .fixup,\"ax\"\n" \ - "3: lea 0(%2,%0,4),%0\n" \ - " jmp 2b\n" \ - ".previous\n" \ - _ASM_EXTABLE_UA(0b, 3b) \ + _ASM_EXTABLE_TYPE_REG(0b, 2b, EX_TYPE_UCOPY_LEN4, %2) \ _ASM_EXTABLE_UA(1b, 2b) \ : "=&c"(size), "=&D" (__d0) \ : "r"(size & 3), "0"(size / 4), "1"(addr), "a"(0)); \ @@ -149,10 +145,6 @@ __copy_user_intel(void __user *to, const "36: movl %%eax, %0\n" "37: rep; movsb\n" "100:\n" - ".section .fixup,\"ax\"\n" - "101: lea 0(%%eax,%0,4),%0\n" - " jmp 100b\n" - ".previous\n" _ASM_EXTABLE_UA(1b, 100b) _ASM_EXTABLE_UA(2b, 100b) _ASM_EXTABLE_UA(3b, 100b) @@ -190,7 +182,7 @@ __copy_user_intel(void __user *to, const _ASM_EXTABLE_UA(35b, 100b) _ASM_EXTABLE_UA(36b, 100b) _ASM_EXTABLE_UA(37b, 100b) - _ASM_EXTABLE_UA(99b, 101b) + _ASM_EXTABLE_TYPE_REG(99b, 100b, EX_TYPE_UCOPY_LEN4, %%eax) : "=&c"(size), "=&D" (d0), "=&S" (d1) : "1"(to), "2"(from), "0"(size) : "eax", "edx", "memory"); @@ -255,10 +247,6 @@ static unsigned long __copy_user_intel_n " movl %%eax,%0\n" "7: rep; movsb\n" "8:\n" - ".section .fixup,\"ax\"\n" - "9: lea 0(%%eax,%0,4),%0\n" - " jmp 8b\n" - ".previous\n" _ASM_EXTABLE_UA(0b, 8b) _ASM_EXTABLE_UA(1b, 8b) _ASM_EXTABLE_UA(2b, 8b) @@ -277,7 +265,7 @@ static unsigned long __copy_user_intel_n _ASM_EXTABLE_UA(81b, 8b) _ASM_EXTABLE_UA(14b, 8b) _ASM_EXTABLE_UA(91b, 8b) - _ASM_EXTABLE_UA(6b, 9b) + _ASM_EXTABLE_TYPE_REG(6b, 8b, EX_TYPE_UCOPY_LEN4, %%eax) _ASM_EXTABLE_UA(7b, 8b) : "=&c"(size), "=&D" (d0), "=&S" (d1) : "1"(to), "2"(from), "0"(size) @@ -315,14 +303,8 @@ do { \ " movl %3,%0\n" \ "1: rep; movsb\n" \ "2:\n" \ - ".section .fixup,\"ax\"\n" \ - "5: addl %3,%0\n" \ - " jmp 2b\n" \ - "3: lea 0(%3,%0,4),%0\n" \ - " jmp 2b\n" \ - ".previous\n" \ - _ASM_EXTABLE_UA(4b, 5b) \ - _ASM_EXTABLE_UA(0b, 3b) \ + _ASM_EXTABLE_TYPE_REG(4b, 2b, EX_TYPE_UCOPY_LEN1, %3) \ + _ASM_EXTABLE_TYPE_REG(0b, 2b, EX_TYPE_UCOPY_LEN4, %3) \ _ASM_EXTABLE_UA(1b, 2b) \ : "=&c"(size), "=&D" (__d0), "=&S" (__d1), "=r"(__d2) \ : "3"(size), "0"(size), "1"(to), "2"(from) \ --- a/arch/x86/lib/usercopy_64.c +++ b/arch/x86/lib/usercopy_64.c @@ -35,12 +35,10 @@ unsigned long __clear_user(void __user * " incq %[dst]\n" " decl %%ecx ; jnz 1b\n" "2:\n" - ".section .fixup,\"ax\"\n" - "3: lea 0(%[size1],%[size8],8),%[size8]\n" - " jmp 2b\n" - ".previous\n" - _ASM_EXTABLE_UA(0b, 3b) + + _ASM_EXTABLE_TYPE_REG(0b, 2b, EX_TYPE_UCOPY_LEN8, %[size1]) _ASM_EXTABLE_UA(1b, 2b) + : [size8] "=&c"(size), [dst] "=&D" (__d0) : [size1] "r"(size & 7), "[size8]" (size / 8), "[dst]"(addr)); clac(); --- a/arch/x86/mm/extable.c +++ b/arch/x86/mm/extable.c @@ -145,6 +145,13 @@ static bool ex_handler_imm_reg(const str return ex_handler_default(fixup, regs); } +static bool ex_handler_ucopy_leng(const struct exception_table_entry *fixup, + struct pt_regs *regs, int trapnr, int reg, int imm) +{ + regs->cx = imm * regs->cx + *pt_regs_nr(regs, reg); + return ex_handler_uaccess(fixup, regs, trapnr); +} + int ex_get_fixup_type(unsigned long ip) { const struct exception_table_entry *e = search_exception_tables(ip); @@ -217,6 +224,8 @@ int fixup_exception(struct pt_regs *regs return ex_handler_imm_reg(e, regs, reg, imm); case EX_TYPE_FAULT_SGX: return ex_handler_sgx(e, regs, trapnr); + case EX_TYPE_UCOPY_LEN: + return ex_handler_ucopy_leng(e, regs, trapnr, reg, imm); } BUG(); }
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