Messages in this thread Patch in this message | | | Subject | Re: [RFC PATCH 13/12] Retpoline vs. CONFIG_TRIM_UNUSED_SYMBOLS | From | David Woodhouse <> | Date | Sun, 07 Jan 2018 08:03:11 +0000 |
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On Sun, 2018-01-07 at 00:10 +0000, David Woodhouse wrote: > Arjan pointed out that CONFIG_TRIM_UNUSED_SYMBOLS *really* doesn't like > the dot in the symbols that GCC uses for the thunks. > > This seems to work, although my eyes are bleeding just a little bit. > > Given this, and the hack we already needed for MODVERSIONS, I wonder if > a better approach might be to export the thunks using underscores in > place of the dots, which is a relatively simple abuse of > __EXPORT_SYMBOL(__x86_indirect_thunk_foo,__x86.indirect_thunk.foo,), > and then have a hack either when generating or loading modules to do > the same replacement.
Alternatively, and much simpler... HJ (or Igor), please can we change the GCC patches so that the __x86.indirect_thunk.rxx symbols don't have those awful dots in them? They are causing *lots* of pain.
Or we could build *modules* with the inline thunk and lose the ability to ALTERNATIVE it away, I suppose.
> diff --git a/arch/x86/lib/retpoline.S b/arch/x86/lib/retpoline.S > index ccb117a4588b..64d7a45ea954 100644 > --- a/arch/x86/lib/retpoline.S > +++ b/arch/x86/lib/retpoline.S > @@ -8,7 +8,13 @@ > #include > #include > > -.macro THUNK reg > +#ifdef CONFIG_TRIM_UNUSED_KSYMS > +#define EXPORT_REG(reg) __is_defined(__KSYM___x86_indirect_thunk_ ## reg) > +#else > +#define EXPORT_REG(reg) 1 > +#endif > + > +.macro THUNK reg export > .section .text.__x86.indirect_thunk.\reg > > ENTRY(__x86.indirect_thunk.\reg) > @@ -16,15 +22,33 @@ ENTRY(__x86.indirect_thunk.\reg) > NOSPEC_JMP %\reg > CFI_ENDPROC > ENDPROC(__x86.indirect_thunk.\reg) > -EXPORT_SYMBOL(__x86.indirect_thunk.\reg) > + > +.if \export > + EXPORT_SYMBOL_FORCE(__x86.indirect_thunk.\reg) > +.endif > .endm > > -#ifdef CONFIG_64BIT > -.irp reg rax rbx rcx rdx rsi rdi rbp r8 r9 r10 r11 r12 r13 r14 r15 > - THUNK \reg > -.endr > +#ifdef __KSYM_DEPS__ > +#define GENERATE_THUNK(reg) EXPORT_SYMBOL(__x86.indirect_thunk. ## reg) > #else > -.irp reg eax ebx ecx edx esi edi ebp > - THUNK \reg > -.endr > +#define GENERATE_THUNK(reg) THUNK reg EXPORT_REG(reg) > +#endif > + > +GENERATE_THUNK(_ASM_AX) > +GENERATE_THUNK(_ASM_BX) > +GENERATE_THUNK(_ASM_CX) > +GENERATE_THUNK(_ASM_DX) > +GENERATE_THUNK(_ASM_SI) > +GENERATE_THUNK(_ASM_DI) > +GENERATE_THUNK(_ASM_BP) > +GENERATE_THUNK(_ASM_SP) > +#ifdef CONFIG_64BIT > +GENERATE_THUNK(r8) > +GENERATE_THUNK(r9) > +GENERATE_THUNK(r10) > +GENERATE_THUNK(r11) > +GENERATE_THUNK(r12) > +GENERATE_THUNK(r13) > +GENERATE_THUNK(r14) > +GENERATE_THUNK(r15) > #endif > diff --git a/include/asm-generic/export.h b/include/asm-generic/export.h > index 719db1968d81..b13bb65e2530 100644 > --- a/include/asm-generic/export.h > +++ b/include/asm-generic/export.h > @@ -63,33 +63,33 @@ KSYM(__kcrctab_\name): > > #if defined(__KSYM_DEPS__) > > -#define __EXPORT_SYMBOL(sym, val, sec) === __KSYM_##sym === > +#define __EXPORT_SYMBOL(sym, val, sec, force) === __KSYM_##sym === > > #elif defined(CONFIG_TRIM_UNUSED_KSYMS) > > #include > #include > > -#define __EXPORT_SYMBOL(sym, val, sec) \ > - __cond_export_sym(sym, val, sec, __is_defined(__KSYM_##sym)) > +#define __EXPORT_SYMBOL(sym, val, sec, force) \ > + __cond_export_sym(sym, val, sec, __or(force, __is_defined(__KSYM_##sym))) > #define __cond_export_sym(sym, val, sec, conf) \ > ___cond_export_sym(sym, val, sec, conf) > #define ___cond_export_sym(sym, val, sec, enabled) \ > __cond_export_sym_##enabled(sym, val, sec) > #define __cond_export_sym_1(sym, val, sec) ___EXPORT_SYMBOL sym, val, sec > #define __cond_export_sym_0(sym, val, sec) /* nothing */ > - > #else > -#define __EXPORT_SYMBOL(sym, val, sec) ___EXPORT_SYMBOL sym, val, sec > +#define __EXPORT_SYMBOL(sym, val, sec, force) ___EXPORT_SYMBOL sym, val, sec > #endif > > #define EXPORT_SYMBOL(name) \ > - __EXPORT_SYMBOL(name, KSYM_FUNC(KSYM(name)),) > + __EXPORT_SYMBOL(name, KSYM_FUNC(KSYM(name)), , 0) > #define EXPORT_SYMBOL_GPL(name) \ > - __EXPORT_SYMBOL(name, KSYM_FUNC(KSYM(name)), _gpl) > + __EXPORT_SYMBOL(name, KSYM_FUNC(KSYM(name)), _gpl, 0) > #define EXPORT_DATA_SYMBOL(name) \ > - __EXPORT_SYMBOL(name, KSYM(name),) > + __EXPORT_SYMBOL(name, KSYM(name), , 0) > #define EXPORT_DATA_SYMBOL_GPL(name) \ > - __EXPORT_SYMBOL(name, KSYM(name),_gpl) > - > + __EXPORT_SYMBOL(name, KSYM(name), _gpl, 0) > +#define EXPORT_SYMBOL_FORCE(name) \ > + __EXPORT_SYMBOL(name, KSYM(name), , 1) > #endif > diff --git a/scripts/adjust_autoksyms.sh b/scripts/adjust_autoksyms.sh > index 513da1a4a2da..991cd136291b 100755 > --- a/scripts/adjust_autoksyms.sh > +++ b/scripts/adjust_autoksyms.sh > @@ -60,7 +60,7 @@ cat > "$new_ksyms_file" << EOT > > EOT > [ "$(ls -A "$MODVERDIR")" ] && > -sed -ns -e '3{s/ /\n/g;/^$/!p;}' "$MODVERDIR"/*.mod | sort -u | > +sed -ns -e '3{s/ /\n/g;/^$/!p;}' "$MODVERDIR"/*.mod | sort -u | tr . _ | > while read sym; do > if [ -n "$CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX" ]; then > sym="${sym#_}"[unhandled content-type:application/x-pkcs7-signature] | |