| Message ID | 20180525080354.13295-9-christophe.lyon@st.com |
|---|---|
| State | New |
| Headers | show |
| Series | FDPIC ARM for ARM | expand |
Hi Christophe, On 25/05/18 09:03, Christophe Lyon wrote: > When checking the address of a weak symbol in an executable, it is > mandatory to use the GOTFUNCDESC scheme so that the address==NULL > semantic is valid if the symbol is not present in the final link. > > 2018-XX-XX Christophe Lyon <christophe.lyon@st.com> > Mickaël Guêné <mickael.guene@st.com> > > gcc/ > * config/arm/arm.c (arm_local_funcdesc_p): New function. > (legitimize_pic_address): Handle weak symbols in FDPIC mode. > (arm_assemble_integer): Likewise. > > Change-Id: I3fa0b63bc0f672903f405aa72cc46052de1c0feb > > diff --git a/gcc/config/arm/arm.c b/gcc/config/arm/arm.c > index bbf8884..025485d 100644 > --- a/gcc/config/arm/arm.c > +++ b/gcc/config/arm/arm.c > @@ -3771,6 +3771,46 @@ arm_options_perform_arch_sanity_checks (void) > } > } > > +/* Test whether a local function descriptor is canonical, i.e., > + whether we can use GOTOFFFUNCDESC to compute the address of the > + function. */ > +static bool > +arm_local_funcdesc_p (rtx fnx) > +{ > + tree fn; > + enum symbol_visibility vis; > + bool ret; > + > + if (!TARGET_FDPIC) > + return TRUE; > + > + if (! SYMBOL_REF_LOCAL_P (fnx)) > + return FALSE; > + > + fn = SYMBOL_REF_DECL (fnx); > + > + if (! fn) > + return FALSE; > + > + /* Local function declared as weak must use GOTFUNCDESC so their > + FUNCDESC is NULL if they are not linked in. */ > + if (DECL_WEAK(fn)) > + return FALSE; > + > + vis = DECL_VISIBILITY (fn); > + > + if (vis == VISIBILITY_PROTECTED) > + /* Private function descriptors for protected functions are not > + canonical. Temporarily change the visibility to global. */ > + vis = VISIBILITY_DEFAULT; > + > + ret = default_binds_local_p_1 (fn, flag_pic); > + > + DECL_VISIBILITY (fn) = vis; > + I'm a bit suspicious of the above few lines. Does this function end up changing the visibility of 'fn'? If so, this function is not a pure predicate function and should be documented that it modifies some part of its argument. Or did you mean to change the visibility before the call to default_binds_local_p_1 and restore it afterwards? Thanks, Kyrill > + return ret; > +} > + > static void > arm_add_gc_roots (void) > { > @@ -7488,7 +7528,9 @@ legitimize_pic_address (rtx orig, machine_mode mode, rtx reg) > || (GET_CODE (orig) == SYMBOL_REF > && SYMBOL_REF_LOCAL_P (orig) > && (SYMBOL_REF_DECL (orig) > - ? !DECL_WEAK (SYMBOL_REF_DECL (orig)) : 1))) > + ? !DECL_WEAK (SYMBOL_REF_DECL (orig)) : 1) > + && (!SYMBOL_REF_FUNCTION_P(orig) > + || arm_local_funcdesc_p (orig)))) > && NEED_GOT_RELOC > && arm_pic_data_is_text_relative) > insn = arm_pic_static_addr (orig, reg); > @@ -23072,7 +23114,9 @@ arm_assemble_integer (rtx x, unsigned int size, int aligned_p) > || (GET_CODE (x) == SYMBOL_REF > && (!SYMBOL_REF_LOCAL_P (x) > || (SYMBOL_REF_DECL (x) > - ? DECL_WEAK (SYMBOL_REF_DECL (x)) : 0)))) > + ? DECL_WEAK (SYMBOL_REF_DECL (x)) : 0) > + || (SYMBOL_REF_FUNCTION_P (x) > + && !arm_local_funcdesc_p (x))))) > { > if (TARGET_FDPIC && SYMBOL_REF_FUNCTION_P (x)) > fputs ("(GOTFUNCDESC)", asm_out_file); > -- > 2.6.3 >
diff --git a/gcc/config/arm/arm.c b/gcc/config/arm/arm.c index bbf8884..025485d 100644 --- a/gcc/config/arm/arm.c +++ b/gcc/config/arm/arm.c @@ -3771,6 +3771,46 @@ arm_options_perform_arch_sanity_checks (void) } } +/* Test whether a local function descriptor is canonical, i.e., + whether we can use GOTOFFFUNCDESC to compute the address of the + function. */ +static bool +arm_local_funcdesc_p (rtx fnx) +{ + tree fn; + enum symbol_visibility vis; + bool ret; + + if (!TARGET_FDPIC) + return TRUE; + + if (! SYMBOL_REF_LOCAL_P (fnx)) + return FALSE; + + fn = SYMBOL_REF_DECL (fnx); + + if (! fn) + return FALSE; + + /* Local function declared as weak must use GOTFUNCDESC so their + FUNCDESC is NULL if they are not linked in. */ + if (DECL_WEAK(fn)) + return FALSE; + + vis = DECL_VISIBILITY (fn); + + if (vis == VISIBILITY_PROTECTED) + /* Private function descriptors for protected functions are not + canonical. Temporarily change the visibility to global. */ + vis = VISIBILITY_DEFAULT; + + ret = default_binds_local_p_1 (fn, flag_pic); + + DECL_VISIBILITY (fn) = vis; + + return ret; +} + static void arm_add_gc_roots (void) { @@ -7488,7 +7528,9 @@ legitimize_pic_address (rtx orig, machine_mode mode, rtx reg) || (GET_CODE (orig) == SYMBOL_REF && SYMBOL_REF_LOCAL_P (orig) && (SYMBOL_REF_DECL (orig) - ? !DECL_WEAK (SYMBOL_REF_DECL (orig)) : 1))) + ? !DECL_WEAK (SYMBOL_REF_DECL (orig)) : 1) + && (!SYMBOL_REF_FUNCTION_P(orig) + || arm_local_funcdesc_p (orig)))) && NEED_GOT_RELOC && arm_pic_data_is_text_relative) insn = arm_pic_static_addr (orig, reg); @@ -23072,7 +23114,9 @@ arm_assemble_integer (rtx x, unsigned int size, int aligned_p) || (GET_CODE (x) == SYMBOL_REF && (!SYMBOL_REF_LOCAL_P (x) || (SYMBOL_REF_DECL (x) - ? DECL_WEAK (SYMBOL_REF_DECL (x)) : 0)))) + ? DECL_WEAK (SYMBOL_REF_DECL (x)) : 0) + || (SYMBOL_REF_FUNCTION_P (x) + && !arm_local_funcdesc_p (x))))) { if (TARGET_FDPIC && SYMBOL_REF_FUNCTION_P (x)) fputs ("(GOTFUNCDESC)", asm_out_file);