Sure, I can use __x86_indirect_thunk_rax. H.J.
> -----Original Message----- > From: David Woodhouse [mailto:[email protected]] > Sent: Sunday, January 07, 2018 12:03 AM > To: Andi Kleen <[email protected]>; Van De Ven, Arjan > <[email protected]>; Lu, Hongjiu <[email protected]>; > Tsimbalist, Igor V <[email protected]> > Cc: Paul Turner <[email protected]>; LKML <[email protected]>; > Linus Torvalds <[email protected]>; Greg Kroah-Hartman > <[email protected]>; Tim Chen <[email protected]>; > Hansen, Dave <[email protected]>; [email protected]; Kees Cook > <[email protected]>; Rik van Riel <[email protected]>; Peter Zijlstra > <[email protected]>; Andy Lutomirski <[email protected]>; Jiri > Kosina <[email protected]>; [email protected] > Subject: Re: [RFC PATCH 13/12] Retpoline vs. > CONFIG_TRIM_UNUSED_SYMBOLS > > 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#_}"
