On 8 June 2018 at 12:51, Richard Earnshaw (lists) <richard.earns...@arm.com> 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 <christophe.l...@st.com> >>> Mickaël Guêné <mickael.gu...@st.com> >>> >>> 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 >>> >> >