[Request for help] issue when add relative extable support to riscv64
Kefeng Wang
wangkefeng.wang at huawei.com
Fri Sep 17 18:23:48 PDT 2021
On 2021/9/18 0:26, Jisheng Zhang wrote:
> On Fri, 17 Sep 2021 23:57:33 +0800 Jisheng Zhang wrote:
>
>> Hi,
>>
>> Now the extable entry contains 16bytes for riscv64 -- 8bytes for the insn and
>> another 8bytes for the fixup. This wastes mem a bit. I think we can add
>> the relative extable support. A draft patch put at the end of this mail. But
>> I met abnormal build errors:
>>
>> FATAL: modpost: The relocation at __ex_table+0x0 references
>> section "__ex_table" which is not executable, IOW
>> it is not possible for the kernel to fault
>> at that address. Something is seriously wrong
>> and should be fixed.
I try this before, and meet the same issue, and add norelax to the label,
but it won't fix the error. seems that we con't find the lable from the
text?
82 index 1b00badb9f87..cb1aca8e8a23 100644
83 --- a/arch/riscv/include/asm/futex.h
84 +++ b/arch/riscv/include/asm/futex.h
85 @@ -23,17 +23,18 @@
86 uintptr_t tmp; \
87 __enable_user_access(); \
88 __asm__ __volatile__ ( \
89 + " .option push \n" \
90 + " .option norelax \n" \
91 + " .option norvc \n" \
92 "1: " insn " \n" \
93 + " .option pop \n" \
94 "2: \n" \
>> I investigated this issue but didn't find any clue. Any suggestion
>> is appreciated!
>>
>> Thanks
>>
> sorry, I missed two files, the completed patch is here:
>
> diff --git a/arch/riscv/include/asm/Kbuild b/arch/riscv/include/asm/Kbuild
> index 445ccc97305a..57b86fd9916c 100644
> --- a/arch/riscv/include/asm/Kbuild
> +++ b/arch/riscv/include/asm/Kbuild
> @@ -1,6 +1,5 @@
> # SPDX-License-Identifier: GPL-2.0
> generic-y += early_ioremap.h
> -generic-y += extable.h
> generic-y += flat.h
> generic-y += kvm_para.h
> generic-y += user.h
> diff --git a/arch/riscv/include/asm/extable.h b/arch/riscv/include/asm/extable.h
> new file mode 100644
> index 000000000000..3a055c7d6a5b
> --- /dev/null
> +++ b/arch/riscv/include/asm/extable.h
> @@ -0,0 +1,12 @@
> +#ifndef __ASM_EXTABLE_H
> +#define __ASM_EXTABLE_H
> +
> +struct exception_table_entry
> +{
> + int insn, fixup;
> +};
> +
> +#define ARCH_HAS_RELATIVE_EXTABLE
> +
> +extern int fixup_exception(struct pt_regs *regs);
> +#endif
> diff --git a/arch/riscv/include/asm/futex.h b/arch/riscv/include/asm/futex.h
> index 1b00badb9f87..b220b8387c9d 100644
> --- a/arch/riscv/include/asm/futex.h
> +++ b/arch/riscv/include/asm/futex.h
> @@ -31,8 +31,8 @@
> " jump 2b,%[t] \n" \
> " .previous \n" \
> " .section __ex_table,\"a\" \n" \
> - " .balign " RISCV_SZPTR " \n" \
> - " " RISCV_PTR " 1b, 3b \n" \
> + " .balign 4 \n" \
> + " .word (1b-.), (3b-.) \n" \
> " .previous \n" \
> : [r] "+r" (ret), [ov] "=&r" (oldval), \
> [u] "+m" (*uaddr), [t] "=&r" (tmp) \
> @@ -104,9 +104,9 @@ futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
> " jump 3b,%[t] \n"
> " .previous \n"
> " .section __ex_table,\"a\" \n"
> - " .balign " RISCV_SZPTR " \n"
> - " " RISCV_PTR " 1b, 4b \n"
> - " " RISCV_PTR " 2b, 4b \n"
> + " .balign 4 \n"
> + " .word (1b-.), (4b-.) \n"
> + " .word (2b-.), (4b-.) \n"
> " .previous \n"
> : [r] "+r" (ret), [v] "=&r" (val), [u] "+m" (*uaddr), [t] "=&r" (tmp)
> : [ov] "Jr" (oldval), [nv] "Jr" (newval), [e] "i" (-EFAULT)
> diff --git a/arch/riscv/include/asm/uaccess.h b/arch/riscv/include/asm/uaccess.h
> index f314ff44c48d..097ed3df9b17 100644
> --- a/arch/riscv/include/asm/uaccess.h
> +++ b/arch/riscv/include/asm/uaccess.h
> @@ -94,8 +94,8 @@ do { \
> " jump 2b, %2\n" \
> " .previous\n" \
> " .section __ex_table,\"a\"\n" \
> - " .balign " RISCV_SZPTR "\n" \
> - " " RISCV_PTR " 1b, 3b\n" \
> + " .balign 4 \n" \
> + " .word (1b - .), (3b - .)\n" \
> " .previous" \
> : "+r" (err), "=&r" (__x), "=r" (__tmp) \
> : "m" (*(ptr)), "i" (-EFAULT)); \
> @@ -126,9 +126,9 @@ do { \
> " jump 3b, %3\n" \
> " .previous\n" \
> " .section __ex_table,\"a\"\n" \
> - " .balign " RISCV_SZPTR "\n" \
> - " " RISCV_PTR " 1b, 4b\n" \
> - " " RISCV_PTR " 2b, 4b\n" \
> + " .balign 4 \n" \
> + " .word (1b - .), (4b - .)\n" \
> + " .word (2b - .), (4b - .)\n" \
> " .previous" \
> : "+r" (err), "=&r" (__lo), "=r" (__hi), \
> "=r" (__tmp) \
> @@ -234,8 +234,8 @@ do { \
> " jump 2b, %1\n" \
> " .previous\n" \
> " .section __ex_table,\"a\"\n" \
> - " .balign " RISCV_SZPTR "\n" \
> - " " RISCV_PTR " 1b, 3b\n" \
> + " .balign 4 \n" \
> + " .word (1b - .), (3b - .)\n" \
> " .previous" \
> : "+r" (err), "=r" (__tmp), "=m" (*(ptr)) \
> : "rJ" (__x), "i" (-EFAULT)); \
> @@ -263,9 +263,9 @@ do { \
> " jump 3b, %1\n" \
> " .previous\n" \
> " .section __ex_table,\"a\"\n" \
> - " .balign " RISCV_SZPTR "\n" \
> - " " RISCV_PTR " 1b, 4b\n" \
> - " " RISCV_PTR " 2b, 4b\n" \
> + " .balign 4 \n" \
> + " .word (1b - .), (4b - .)\n" \
> + " .word (2b - .), (4b - .)\n" \
> " .previous" \
> : "+r" (err), "=r" (__tmp), \
> "=m" (__ptr[__LSW]), \
> @@ -418,8 +418,8 @@ unsigned long __must_check clear_user(void __user *to, unsigned long n)
> " jump 1b, %[rc]\n" \
> ".previous\n" \
> ".section __ex_table,\"a\"\n" \
> - ".balign " RISCV_SZPTR "\n" \
> - " " RISCV_PTR " 1b, 2b\n" \
> + ".balign 4 \n" \
> + ".word (1b-.), (2b-.)\n" \
> ".previous\n" \
> : [ret] "=&r" (__ret), \
> [rc] "=&r" (__rc), \
> @@ -444,8 +444,8 @@ unsigned long __must_check clear_user(void __user *to, unsigned long n)
> " jump 1b, %[rc]\n" \
> ".previous\n" \
> ".section __ex_table,\"a\"\n" \
> - ".balign " RISCV_SZPTR "\n" \
> - " " RISCV_PTR " 1b, 2b\n" \
> + ".balign 4 \n" \
> + ".word (1b-.), (2b-.)\n" \
> ".previous\n" \
> : [ret] "=&r" (__ret), \
> [rc] "=&r" (__rc), \
> diff --git a/arch/riscv/lib/uaccess.S b/arch/riscv/lib/uaccess.S
> index 63bc691cff91..b346ecb2a051 100644
> --- a/arch/riscv/lib/uaccess.S
> +++ b/arch/riscv/lib/uaccess.S
> @@ -7,8 +7,8 @@
> 100:
> \op \reg, \addr
> .section __ex_table,"a"
> - .balign RISCV_SZPTR
> - RISCV_PTR 100b, \lbl
> + .balign 4
> + .word (100b - .), (\lbl - .)
> .previous
> .endm
>
> diff --git a/arch/riscv/mm/extable.c b/arch/riscv/mm/extable.c
> index 2fc729422151..6aa8ffac4be7 100644
> --- a/arch/riscv/mm/extable.c
> +++ b/arch/riscv/mm/extable.c
> @@ -17,7 +17,7 @@ int fixup_exception(struct pt_regs *regs)
>
> fixup = search_exception_tables(regs->epc);
> if (fixup) {
> - regs->epc = fixup->fixup;
> + regs->epc = (unsigned long)&fixup->fixup + fixup->fixup;
> return 1;
> }
> return 0;
> diff --git a/scripts/sorttable.c b/scripts/sorttable.c
> index f355869c65cd..7c5f6a361946 100644
> --- a/scripts/sorttable.c
> +++ b/scripts/sorttable.c
> @@ -342,6 +342,7 @@ static int do_file(char const *const fname, void *addr)
> case EM_PARISC:
> case EM_PPC:
> case EM_PPC64:
> + case EM_RISCV:
> custom_sort = sort_relative_table;
> break;
> case EM_ARCOMPACT:
> @@ -349,7 +350,6 @@ static int do_file(char const *const fname, void *addr)
> case EM_ARM:
> case EM_MICROBLAZE:
> case EM_MIPS:
> - case EM_RISCV:
> case EM_XTENSA:
> break;
> default:
>
>
>> diff --git a/arch/riscv/include/asm/Kbuild b/arch/riscv/include/asm/Kbuild
>> index 445ccc97305a..57b86fd9916c 100644
>> --- a/arch/riscv/include/asm/Kbuild
>> +++ b/arch/riscv/include/asm/Kbuild
>> @@ -1,6 +1,5 @@
>> # SPDX-License-Identifier: GPL-2.0
>> generic-y += early_ioremap.h
>> -generic-y += extable.h
>> generic-y += flat.h
>> generic-y += kvm_para.h
>> generic-y += user.h
>> diff --git a/arch/riscv/include/asm/futex.h b/arch/riscv/include/asm/futex.h
>> index 1b00badb9f87..b220b8387c9d 100644
>> --- a/arch/riscv/include/asm/futex.h
>> +++ b/arch/riscv/include/asm/futex.h
>> @@ -31,8 +31,8 @@
>> " jump 2b,%[t] \n" \
>> " .previous \n" \
>> " .section __ex_table,\"a\" \n" \
>> - " .balign " RISCV_SZPTR " \n" \
>> - " " RISCV_PTR " 1b, 3b \n" \
>> + " .balign 4 \n" \
>> + " .word (1b-.), (3b-.) \n" \
>> " .previous \n" \
>> : [r] "+r" (ret), [ov] "=&r" (oldval), \
>> [u] "+m" (*uaddr), [t] "=&r" (tmp) \
>> @@ -104,9 +104,9 @@ futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
>> " jump 3b,%[t] \n"
>> " .previous \n"
>> " .section __ex_table,\"a\" \n"
>> - " .balign " RISCV_SZPTR " \n"
>> - " " RISCV_PTR " 1b, 4b \n"
>> - " " RISCV_PTR " 2b, 4b \n"
>> + " .balign 4 \n"
>> + " .word (1b-.), (4b-.) \n"
>> + " .word (2b-.), (4b-.) \n"
>> " .previous \n"
>> : [r] "+r" (ret), [v] "=&r" (val), [u] "+m" (*uaddr), [t] "=&r" (tmp)
>> : [ov] "Jr" (oldval), [nv] "Jr" (newval), [e] "i" (-EFAULT)
>> diff --git a/arch/riscv/include/asm/uaccess.h b/arch/riscv/include/asm/uaccess.h
>> index f314ff44c48d..097ed3df9b17 100644
>> --- a/arch/riscv/include/asm/uaccess.h
>> +++ b/arch/riscv/include/asm/uaccess.h
>> @@ -94,8 +94,8 @@ do { \
>> " jump 2b, %2\n" \
>> " .previous\n" \
>> " .section __ex_table,\"a\"\n" \
>> - " .balign " RISCV_SZPTR "\n" \
>> - " " RISCV_PTR " 1b, 3b\n" \
>> + " .balign 4 \n" \
>> + " .word (1b - .), (3b - .)\n" \
>> " .previous" \
>> : "+r" (err), "=&r" (__x), "=r" (__tmp) \
>> : "m" (*(ptr)), "i" (-EFAULT)); \
>> @@ -126,9 +126,9 @@ do { \
>> " jump 3b, %3\n" \
>> " .previous\n" \
>> " .section __ex_table,\"a\"\n" \
>> - " .balign " RISCV_SZPTR "\n" \
>> - " " RISCV_PTR " 1b, 4b\n" \
>> - " " RISCV_PTR " 2b, 4b\n" \
>> + " .balign 4 \n" \
>> + " .word (1b - .), (4b - .)\n" \
>> + " .word (2b - .), (4b - .)\n" \
>> " .previous" \
>> : "+r" (err), "=&r" (__lo), "=r" (__hi), \
>> "=r" (__tmp) \
>> @@ -234,8 +234,8 @@ do { \
>> " jump 2b, %1\n" \
>> " .previous\n" \
>> " .section __ex_table,\"a\"\n" \
>> - " .balign " RISCV_SZPTR "\n" \
>> - " " RISCV_PTR " 1b, 3b\n" \
>> + " .balign 4 \n" \
>> + " .word (1b - .), (3b - .)\n" \
>> " .previous" \
>> : "+r" (err), "=r" (__tmp), "=m" (*(ptr)) \
>> : "rJ" (__x), "i" (-EFAULT)); \
>> @@ -263,9 +263,9 @@ do { \
>> " jump 3b, %1\n" \
>> " .previous\n" \
>> " .section __ex_table,\"a\"\n" \
>> - " .balign " RISCV_SZPTR "\n" \
>> - " " RISCV_PTR " 1b, 4b\n" \
>> - " " RISCV_PTR " 2b, 4b\n" \
>> + " .balign 4 \n" \
>> + " .word (1b - .), (4b - .)\n" \
>> + " .word (2b - .), (4b - .)\n" \
>> " .previous" \
>> : "+r" (err), "=r" (__tmp), \
>> "=m" (__ptr[__LSW]), \
>> @@ -418,8 +418,8 @@ unsigned long __must_check clear_user(void __user *to, unsigned long n)
>> " jump 1b, %[rc]\n" \
>> ".previous\n" \
>> ".section __ex_table,\"a\"\n" \
>> - ".balign " RISCV_SZPTR "\n" \
>> - " " RISCV_PTR " 1b, 2b\n" \
>> + ".balign 4 \n" \
>> + ".word (1b-.), (2b-.)\n" \
>> ".previous\n" \
>> : [ret] "=&r" (__ret), \
>> [rc] "=&r" (__rc), \
>> @@ -444,8 +444,8 @@ unsigned long __must_check clear_user(void __user *to, unsigned long n)
>> " jump 1b, %[rc]\n" \
>> ".previous\n" \
>> ".section __ex_table,\"a\"\n" \
>> - ".balign " RISCV_SZPTR "\n" \
>> - " " RISCV_PTR " 1b, 2b\n" \
>> + ".balign 4 \n" \
>> + ".word (1b-.), (2b-.)\n" \
>> ".previous\n" \
>> : [ret] "=&r" (__ret), \
>> [rc] "=&r" (__rc), \
>> diff --git a/arch/riscv/lib/uaccess.S b/arch/riscv/lib/uaccess.S
>> index 63bc691cff91..b346ecb2a051 100644
>> --- a/arch/riscv/lib/uaccess.S
>> +++ b/arch/riscv/lib/uaccess.S
>> @@ -7,8 +7,8 @@
>> 100:
>> \op \reg, \addr
>> .section __ex_table,"a"
>> - .balign RISCV_SZPTR
>> - RISCV_PTR 100b, \lbl
>> + .balign 4
>> + .word (100b - .), (\lbl - .)
>> .previous
>> .endm
>>
>> diff --git a/arch/riscv/mm/extable.c b/arch/riscv/mm/extable.c
>> index 2fc729422151..6aa8ffac4be7 100644
>> --- a/arch/riscv/mm/extable.c
>> +++ b/arch/riscv/mm/extable.c
>> @@ -17,7 +17,7 @@ int fixup_exception(struct pt_regs *regs)
>>
>> fixup = search_exception_tables(regs->epc);
>> if (fixup) {
>> - regs->epc = fixup->fixup;
>> + regs->epc = (unsigned long)&fixup->fixup + fixup->fixup;
>> return 1;
>> }
>> return 0;
>>
>>
>> _______________________________________________
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>> linux-riscv at lists.infradead.org
>> http://lists.infradead.org/mailman/listinfo/linux-riscv
>
>
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