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.
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
>>
>
