On 8 June 2018 at 12:51, Richard Earnshaw (lists)
<[email protected]> wrote:
> On 08/06/18 11:15, Kyrill Tkachov wrote:
>> Hi Christophe,
>>
>> On 25/05/18 09:03, Christophe Lyon wrote:
>>> When restoring a function address, we also have to restore the FDPIC
>>> register value (r9).
>>>
>>> 2018-XX-XX Christophe Lyon <[email protected]>
>>> Mickaël Guêné <[email protected]>
>>>
>>> gcc/
>>> * ginclude/unwind-arm-common.h (unwinder_cache): Add reserved5
>>> field.
>>>
>>> libgcc/
>>> * config/arm/linux-atomic.c (__ARM_ARCH__): Define.
>>> (__kernel_cmpxchg): Add FDPIC support.
>>> (__kernel_dmb): Likewise.
>>> (__fdpic_cmpxchg): New function.
>>> (__fdpic_dmb): New function.
>>> * config/arm/unwind-arm.h (gnu_Unwind_Find_got): New function.
>>> (_Unwind_decode_typeinfo_ptr): Add FDPIC support.
>>> * unwindo-arm-common.inc (UCB_PR_GOT): New.
>>> (funcdesc_t): New struct.
>>> (get_eit_entry): Add FDPIC support.
>>> (unwind_phase2): Likewise.
>>> (unwind_phase2_forced): Likewise.
>>> (__gnu_Unwind_RaiseException): Likewise.
>>> (__gnu_Unwind_Resume): Likewise.
>>> (__gnu_Unwind_Backtrace): Likewise.
>>> * unwind-pe.h (read_encoded_value_with_base): Likewise.
>>>
>>> libstdc++/
>>> * libsupc++/eh_personality.cc (get_ttype_entry): Add FDPIC
>>> support.
>>>
>>> Change-Id: Ic0841eb3d7bfb0b3f6d187cd52a660b8fd394d85
>>>
>>> diff --git a/gcc/ginclude/unwind-arm-common.h
>>> b/gcc/ginclude/unwind-arm-common.h
>>> index 8a1a919..150bd0f 100644
>>> --- a/gcc/ginclude/unwind-arm-common.h
>>> +++ b/gcc/ginclude/unwind-arm-common.h
>>> @@ -91,7 +91,7 @@ extern "C" {
>>> _uw reserved2; /* Personality routine address */
>>> _uw reserved3; /* Saved callsite address */
>>> _uw reserved4; /* Forced unwind stop arg */
>>> - _uw reserved5;
>>> + _uw reserved5; /* Personality routine GOT value in FDPIC
>>> mode. */
>>> }
>>> unwinder_cache;
>>> /* Propagation barrier cache (valid after phase 1): */
>>> diff --git a/libgcc/config/arm/linux-atomic.c
>>> b/libgcc/config/arm/linux-atomic.c
>>> index d334c58..a20ad94 100644
>>> --- a/libgcc/config/arm/linux-atomic.c
>>> +++ b/libgcc/config/arm/linux-atomic.c
>>> @@ -23,13 +23,99 @@ a copy of the GCC Runtime Library Exception along
>>> with this program;
>>> see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
>>> <http://www.gnu.org/licenses/>. */
>>>
>>> +#if defined(__ARM_ARCH_2__)
>>> +# define __ARM_ARCH__ 2
>>> +#endif
>>> +
>>> +#if defined(__ARM_ARCH_3__)
>>> +# define __ARM_ARCH__ 3
>>> +#endif
>>> +
>>> +#if defined(__ARM_ARCH_3M__) || defined(__ARM_ARCH_4__) \
>>> + || defined(__ARM_ARCH_4T__)
>>> +/* We use __ARM_ARCH__ set to 4 here, but in reality it's any
>>> processor with
>>> + long multiply instructions. That includes v3M. */
>>> +# define __ARM_ARCH__ 4
>>> +#endif
>>> +
>>
>> Support for __ARM_ARCH_2__, __ARM_ARCH_3__, __ARM_ARCH_3M__ has been
>> removed in GCC 9
>> so this code is dead.
>
> Better still, use the ACLE pre-defines rather than the awkward GCC
> versions which need updating each time a new architecture variant is added.
>
Indeed, that's a better solution. I did notice discrepancies between
several copies of this code block in various GCC libs.
> R.
>
>>
>> I notice that in the removal I've missed out an occurrence of these in
>> config/arm/lib1funcs.S.
>> If you want to remove those occurrences as a separate patch that would
>> be preapproved.
>>
>> Thanks,
>> Kyrill
>>
>>> +#if defined(__ARM_ARCH_5__) || defined(__ARM_ARCH_5T__) \
>>> + || defined(__ARM_ARCH_5E__) || defined(__ARM_ARCH_5TE__) \
>>> + || defined(__ARM_ARCH_5TEJ__)
>>> +# define __ARM_ARCH__ 5
>>> +#endif
>>> +
>>> +#if defined(__ARM_ARCH_6__) || defined(__ARM_ARCH_6J__) \
>>> + || defined(__ARM_ARCH_6K__) || defined(__ARM_ARCH_6Z__) \
>>> + || defined(__ARM_ARCH_6ZK__) || defined(__ARM_ARCH_6T2__) \
>>> + || defined(__ARM_ARCH_6M__)
>>> +# define __ARM_ARCH__ 6
>>> +#endif
>>> +
>>> +#if defined(__ARM_ARCH_7__) || defined(__ARM_ARCH_7A__) \
>>> + || defined(__ARM_ARCH_7R__) || defined(__ARM_ARCH_7M__) \
>>> + || defined(__ARM_ARCH_7EM__)
>>> +# define __ARM_ARCH__ 7
>>> +#endif
>>> +
>>> +#ifndef __ARM_ARCH__
>>> +#error Unable to determine architecture.
>>> +#endif
>>> +
>>> /* Kernel helper for compare-and-exchange. */
>>> typedef int (__kernel_cmpxchg_t) (int oldval, int newval, int *ptr);
>>> +#if __FDPIC__
>>> +#define __kernel_cmpxchg __fdpic_cmpxchg
>>> +#else
>>> #define __kernel_cmpxchg (*(__kernel_cmpxchg_t *) 0xffff0fc0)
>>> +#endif
>>>
>>> /* Kernel helper for memory barrier. */
>>> typedef void (__kernel_dmb_t) (void);
>>> +#if __FDPIC__
>>> +#define __kernel_dmb __fdpic_dmb
>>> +#else
>>> #define __kernel_dmb (*(__kernel_dmb_t *) 0xffff0fa0)
>>> +#endif
>>> +
>>> +#if __FDPIC__
>>> +static int __fdpic_cmpxchg (int oldval, int newval, int *ptr)
>>> +{
>>> +#if __ARM_ARCH__ < 6
>>> + #error architecture support not yet implemented
>>> + /* Use swap instruction (but is it always safe ? (interrupt?)) */
>>> +#else
>>> + int result;
>>> +
>>> + asm volatile ("1: ldrex r3, [%[ptr]]\n\t"
>>> + "subs r3, r3, %[oldval]\n\t"
>>> + "itt eq\n\t"
>>> + "strexeq r3, %[newval], [%[ptr]]\n\t"
>>> + "teqeq r3, #1\n\t"
>>> + "it eq\n\t"
>>> + "beq 1b\n\t"
>>> + "rsbs %[result], r3, #0\n\t"
>>> + : [result] "=r" (result)
>>> + : [oldval] "r" (oldval) , [newval] "r" (newval), [ptr]
>>> "r" (ptr)
>>> + : "r3");
>>> + return result;
>>> +#endif
>>> +}
>>> +
>>> +static void __fdpic_dmb ()
>>> +{
>>> +#if __ARM_ARCH__ < 6
>>> + /* No op? Perhaps flush write buffer ? */
>>> + return ;
>>> +#else
>>> + #if __ARM_ARCH__ >= 7
>>> + asm volatile ("dmb\n\t");
>>> + #elif __ARM_ARCH__ == 6
>>> + asm volatile ("mcr p15, 0, r0, c7, c10, 5\n\t");
>>> + #endif
>>> +#endif
>>> +}
>>> +
>>> +#endif
>>>
>>> /* Note: we implement byte, short and int versions of atomic
>>> operations using
>>> the above kernel helpers; see linux-atomic-64bit.c for "long long"
>>> (64-bit)
>>> diff --git a/libgcc/config/arm/unwind-arm.h
>>> b/libgcc/config/arm/unwind-arm.h
>>> index 9f7d3f2..a9598eb 100644
>>> --- a/libgcc/config/arm/unwind-arm.h
>>> +++ b/libgcc/config/arm/unwind-arm.h
>>> @@ -36,6 +36,25 @@
>>> #ifdef __cplusplus
>>> extern "C" {
>>> #endif
>>> +_Unwind_Ptr __attribute__((weak)) __gnu_Unwind_Find_got (_Unwind_Ptr);
>>> +
>>> +static inline _Unwind_Ptr gnu_Unwind_Find_got (_Unwind_Ptr ptr)
>>> +{
>>> + _Unwind_Ptr res;
>>> +
>>> + if (__gnu_Unwind_Find_got)
>>> + res = __gnu_Unwind_Find_got (ptr);
>>> + else
>>> + {
>>> + asm volatile ("mov %[result], r9"
>>> + : [result]"=r" (res)
>>> + :
>>> + :);
>>> + }
>>> +
>>> + return res;
>>> +}
>>> +
>>> /* Decode an R_ARM_TARGET2 relocation. */
>>> static inline _Unwind_Word
>>> _Unwind_decode_typeinfo_ptr (_Unwind_Word base __attribute__
>>> ((unused)),
>>> @@ -48,7 +67,12 @@ extern "C" {
>>> if (!tmp)
>>> return 0;
>>>
>>> -#if (defined(linux) && !defined(__uClinux__)) || defined(__NetBSD__) \
>>> +#if __FDPIC__
>>> + /* For FDPIC, we store the offset of the GOT entry. */
>>> + /* So, first get GOT from dynamic linker and then use indirect
>>> access. */
>>> + tmp += gnu_Unwind_Find_got (ptr);
>>> + tmp = *(_Unwind_Word *) tmp;
>>> +#elif (defined(linux) && !defined(__uClinux__)) || defined(__NetBSD__) \
>>> || defined(__FreeBSD__) || defined(__fuchsia__)
>>> /* Pc-relative indirect. */
>>> #define _GLIBCXX_OVERRIDE_TTYPE_ENCODING (DW_EH_PE_pcrel |
>>> DW_EH_PE_indirect)
>>> diff --git a/libgcc/unwind-arm-common.inc b/libgcc/unwind-arm-common.inc
>>> index 76f8fc3..f5415c1 100644
>>> --- a/libgcc/unwind-arm-common.inc
>>> +++ b/libgcc/unwind-arm-common.inc
>>> @@ -62,6 +62,7 @@ __gnu_Unwind_Find_exidx (_Unwind_Ptr, int *);
>>> #define UCB_PR_ADDR(ucbp) ((ucbp)->unwinder_cache.reserved2)
>>> #define UCB_SAVED_CALLSITE_ADDR(ucbp) ((ucbp)->unwinder_cache.reserved3)
>>> #define UCB_FORCED_STOP_ARG(ucbp) ((ucbp)->unwinder_cache.reserved4)
>>> +#define UCB_PR_GOT(ucbp) ((ucbp)->unwinder_cache.reserved5)
>>>
>>> /* Unwind descriptors. */
>>>
>>> @@ -85,6 +86,12 @@ typedef struct __EIT_entry
>>> _uw content;
>>> } __EIT_entry;
>>>
>>> +/* Only used in FDPIC case. */
>>> +struct funcdesc_t {
>>> + unsigned int ptr;
>>> + unsigned int got;
>>> +};
>>> +
>>> /* Assembly helper functions. */
>>>
>>> /* Restore core register state. Never returns. */
>>> @@ -259,7 +266,23 @@ get_eit_entry (_Unwind_Control_Block *ucbp, _uw
>>> return_address)
>>> {
>>> /* One of the predefined standard routines. */
>>> _uw idx = (*(_uw *) ucbp->pr_cache.ehtp >> 24) & 0xf;
>>> +#if __FDPIC__
>>> + {
>>> + struct funcdesc_t *funcdesc
>>> + = (struct funcdesc_t *) __gnu_unwind_get_pr_addr (idx);
>>> + if (funcdesc)
>>> + {
>>> + UCB_PR_ADDR (ucbp) = funcdesc->ptr;
>>> + UCB_PR_GOT (ucbp) = funcdesc->got;
>>> + }
>>> + else
>>> + {
>>> + UCB_PR_ADDR (ucbp) = 0;
>>> + }
>>> + }
>>> +#else
>>> UCB_PR_ADDR (ucbp) = __gnu_unwind_get_pr_addr (idx);
>>> +#endif
>>> if (UCB_PR_ADDR (ucbp) == 0)
>>> {
>>> /* Failed */
>>> @@ -269,7 +292,13 @@ get_eit_entry (_Unwind_Control_Block *ucbp, _uw
>>> return_address)
>>> else
>>> {
>>> /* Execute region offset to PR */
>>> +#if __FDPIC__
>>> UCB_PR_ADDR (ucbp) = selfrel_offset31 (ucbp->pr_cache.ehtp);
>>> + UCB_PR_GOT (ucbp)
>>> + = (unsigned int) gnu_Unwind_Find_got ((_Unwind_Ptr)
>>> UCB_PR_ADDR (ucbp));
>>> +#else
>>> + UCB_PR_ADDR (ucbp) = selfrel_offset31 (ucbp->pr_cache.ehtp);
>>> +#endif
>>> }
>>> return _URC_OK;
>>> }
>>> @@ -291,14 +320,29 @@ unwind_phase2 (_Unwind_Control_Block * ucbp,
>>> phase2_vrs * vrs)
>>> UCB_SAVED_CALLSITE_ADDR (ucbp) = VRS_PC(vrs);
>>>
>>> /* Call the pr to decide what to do. */
>>> +#if __FDPIC__
>>> + {
>>> + volatile struct funcdesc_t funcdesc;
>>> + funcdesc.ptr = UCB_PR_ADDR (ucbp);
>>> + funcdesc.got = UCB_PR_GOT (ucbp);
>>> + pr_result = ((personality_routine) &funcdesc)
>>> + (_US_UNWIND_FRAME_STARTING, ucbp, (_Unwind_Context *) vrs);
>>> + }
>>> +#else
>>> pr_result = ((personality_routine) UCB_PR_ADDR (ucbp))
>>> (_US_UNWIND_FRAME_STARTING, ucbp, (_Unwind_Context *) vrs);
>>> +#endif
>>> }
>>> while (pr_result == _URC_CONTINUE_UNWIND);
>>>
>>> if (pr_result != _URC_INSTALL_CONTEXT)
>>> abort();
>>>
>>> +#if __FDPIC__
>>> + /* r9 could have been lost due to PLT jump. Restore correct
>>> value. */
>>> + vrs->core.r[9] = gnu_Unwind_Find_got (VRS_PC (vrs));
>>> +#endif
>>> +
>>> uw_restore_core_regs (vrs, &vrs->core);
>>> }
>>>
>>> @@ -346,8 +390,18 @@ unwind_phase2_forced (_Unwind_Control_Block
>>> *ucbp, phase2_vrs *entry_vrs,
>>> next_vrs = saved_vrs;
>>>
>>> /* Call the pr to decide what to do. */
>>> +#if __FDPIC__
>>> + {
>>> + volatile struct funcdesc_t funcdesc;
>>> + funcdesc.ptr = UCB_PR_ADDR (ucbp);
>>> + funcdesc.got = UCB_PR_GOT (ucbp);
>>> + pr_result = ((personality_routine) &funcdesc)
>>> + (action, ucbp, (void *) &next_vrs);
>>> + }
>>> +#else
>>> pr_result = ((personality_routine) UCB_PR_ADDR (ucbp))
>>> (action, ucbp, (void *) &next_vrs);
>>> +#endif
>>>
>>> saved_vrs.prev_sp = VRS_SP (&next_vrs);
>>> }
>>> @@ -384,6 +438,11 @@ unwind_phase2_forced (_Unwind_Control_Block
>>> *ucbp, phase2_vrs *entry_vrs,
>>> return _URC_FAILURE;
>>> }
>>>
>>> +#if __FDPIC__
>>> + /* r9 could have been lost due to PLT jump. Restore correct
>>> value. */
>>> + saved_vrs.core.r[9] = gnu_Unwind_Find_got (VRS_PC (&saved_vrs));
>>> +#endif
>>> +
>>> uw_restore_core_regs (&saved_vrs, &saved_vrs.core);
>>> }
>>>
>>> @@ -429,8 +488,18 @@ __gnu_Unwind_RaiseException
>>> (_Unwind_Control_Block * ucbp,
>>> return _URC_FAILURE;
>>>
>>> /* Call the pr to decide what to do. */
>>> +#if __FDPIC__
>>> + {
>>> + volatile struct funcdesc_t funcdesc;
>>> + funcdesc.ptr = UCB_PR_ADDR (ucbp);
>>> + funcdesc.got = UCB_PR_GOT (ucbp);
>>> + pr_result = ((personality_routine) &funcdesc)
>>> + (_US_VIRTUAL_UNWIND_FRAME, ucbp, (void *) &saved_vrs);
>>> + }
>>> +#else
>>> pr_result = ((personality_routine) UCB_PR_ADDR (ucbp))
>>> (_US_VIRTUAL_UNWIND_FRAME, ucbp, (void *) &saved_vrs);
>>> +#endif
>>> }
>>> while (pr_result == _URC_CONTINUE_UNWIND);
>>>
>>> @@ -488,13 +557,27 @@ __gnu_Unwind_Resume (_Unwind_Control_Block *
>>> ucbp, phase2_vrs * entry_vrs)
>>> }
>>>
>>> /* Call the cached PR. */
>>> +#if __FDPIC__
>>> + {
>>> + volatile struct funcdesc_t funcdesc;
>>> + funcdesc.ptr = UCB_PR_ADDR (ucbp);
>>> + funcdesc.got = UCB_PR_GOT (ucbp);
>>> + pr_result = ((personality_routine) &funcdesc)
>>> + (_US_UNWIND_FRAME_RESUME, ucbp, (_Unwind_Context *) entry_vrs);
>>> + }
>>> +#else
>>> pr_result = ((personality_routine) UCB_PR_ADDR (ucbp))
>>> (_US_UNWIND_FRAME_RESUME, ucbp, (_Unwind_Context *) entry_vrs);
>>> +#endif
>>>
>>> switch (pr_result)
>>> {
>>> case _URC_INSTALL_CONTEXT:
>>> /* Upload the registers to enter the landing pad. */
>>> +#if __FDPIC__
>>> + /* r9 could have been lost due to PLT jump. Restore correct
>>> value. */
>>> + entry_vrs->core.r[9] = gnu_Unwind_Find_got (VRS_PC (entry_vrs));
>>> +#endif
>>> uw_restore_core_regs (entry_vrs, &entry_vrs->core);
>>>
>>> case _URC_CONTINUE_UNWIND:
>>> @@ -586,9 +669,20 @@ __gnu_Unwind_Backtrace(_Unwind_Trace_Fn trace,
>>> void * trace_argument,
>>> }
>>>
>>> /* Call the pr to decide what to do. */
>>> +#if __FDPIC__
>>> + {
>>> + volatile struct funcdesc_t funcdesc;
>>> + funcdesc.ptr = UCB_PR_ADDR (ucbp);
>>> + funcdesc.got = UCB_PR_GOT (ucbp);
>>> + code = ((personality_routine) &funcdesc)
>>> + (_US_VIRTUAL_UNWIND_FRAME | _US_FORCE_UNWIND,
>>> + ucbp, (void *) &saved_vrs);
>>> + }
>>> +#else
>>> code = ((personality_routine) UCB_PR_ADDR (ucbp))
>>> (_US_VIRTUAL_UNWIND_FRAME | _US_FORCE_UNWIND,
>>> ucbp, (void *) &saved_vrs);
>>> +#endif
>>> }
>>> while (code != _URC_END_OF_STACK
>>> && code != _URC_FAILURE);
>>> diff --git a/libgcc/unwind-pe.h b/libgcc/unwind-pe.h
>>> index dd5ae95..c18dffe 100644
>>> --- a/libgcc/unwind-pe.h
>>> +++ b/libgcc/unwind-pe.h
>>> @@ -259,10 +259,25 @@ read_encoded_value_with_base (unsigned char
>>> encoding, _Unwind_Ptr base,
>>>
>>> if (result != 0)
>>> {
>>> +#if __FDPIC__
>>> + if ((encoding & DW_EH_PE_pcrel) && (encoding & DW_EH_PE_indirect))
>>> + {
>>> + result += gnu_Unwind_Find_got ((_Unwind_Ptr) u);
>>> + result = *(_Unwind_Internal_Ptr *) result;
>>> + }
>>> + else
>>> + {
>>> + result += ((encoding & 0x70) == DW_EH_PE_pcrel
>>> + ? (_Unwind_Internal_Ptr) u : base);
>>> + if (encoding & DW_EH_PE_indirect)
>>> + result = *(_Unwind_Internal_Ptr *) result;
>>> + }
>>> +#else
>>> result += ((encoding & 0x70) == DW_EH_PE_pcrel
>>> ? (_Unwind_Internal_Ptr) u : base);
>>> if (encoding & DW_EH_PE_indirect)
>>> result = *(_Unwind_Internal_Ptr *) result;
>>> +#endif
>>> }
>>> }
>>>
>>> diff --git a/libstdc++-v3/libsupc++/eh_personality.cc
>>> b/libstdc++-v3/libsupc++/eh_personality.cc
>>> index 1b336c7..138b606 100644
>>> --- a/libstdc++-v3/libsupc++/eh_personality.cc
>>> +++ b/libstdc++-v3/libsupc++/eh_personality.cc
>>> @@ -93,7 +93,13 @@ get_ttype_entry (lsda_header_info *info, _uleb128_t i)
>>> _Unwind_Ptr ptr;
>>>
>>> i *= size_of_encoded_value (info->ttype_encoding);
>>> - read_encoded_value_with_base (info->ttype_encoding, info->ttype_base,
>>> + read_encoded_value_with_base (
>>> +#if __FDPIC__
>>> + (DW_EH_PE_pcrel | DW_EH_PE_indirect),
>>> +#else
>>> + info->ttype_encoding,
>>> +#endif
>>> + info->ttype_base,
>>> info->TType - i, &ptr);
>>>
>>> return reinterpret_cast<const std::type_info *>(ptr);
>>> --
>>> 2.6.3
>>>
>>
>
