From mboxrd@z Thu Jan 1 00:00:00 1970 From: elder@linaro.org (Alex Elder) Date: Thu, 29 Jan 2015 06:44:30 -0600 Subject: [PATCH v2] ARM: teach __asmeq that r11 == fp and r12 == ip In-Reply-To: <1422524686-30462-1-git-send-email-ard.biesheuvel@linaro.org> References: <1422524686-30462-1-git-send-email-ard.biesheuvel@linaro.org> Message-ID: <54CA2B2E.30409@linaro.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 01/29/2015 03:44 AM, Ard Biesheuvel wrote: > The __asmeq macro is used inside inline asm statements to ensure that > register asm variables that explicitly specify a register are mapped > correctly onto those registers when used in inline asm input and output > constraints. However, the string based matching fails to take into account > that 'fp' is often referred to as 'r11' and 'ip' is often referred to as > 'r12', (e.g., by clang), causing false negatives. > > Fix this by making __asmeq consider the ("fp","r11"), ("r11","fp"), > ("ip","r12") and ("r12","ip") cases specifically. > > Signed-off-by: Ard Biesheuvel I'm satisfied. Kind of awkward, but it does what's needed, and solves the general problem rather than a specific instance of it in "bcm_kona_smc.c". I tested it in my environment with "r12" and "ip" used in all combinations and can confirm they all work as desired. Thanks for doing this Ard. Reviewed-by: Alex Elder > --- > v2: > Added r11 but not r10, as the latter is only referred to as 'sl' in > objdump output, but GCC emitted inline asm substitutes the references > with 'r10' instead. sp/lr/pc are unambiguous between GCC and clang. > > Primary purpose of this patch is to fix the incompatibility between clang > and GCC, but the side effect is that it relaxes the requirement imposed on > the programmer to refer to a register by the same name as the compiler does. > If that is seen as a substantial upside by some, we could indeed still decide > to add r10, r13, r14 and r15 (for which no such incompatibility exists) as well. > However, those are not currently used in __asmeq invocations anywhere under > arch/arm > > arch/arm/include/asm/compiler.h | 15 ++++++++++++++- > 1 file changed, 14 insertions(+), 1 deletion(-) > > diff --git a/arch/arm/include/asm/compiler.h b/arch/arm/include/asm/compiler.h > index 8155db2f7fa1..29fe85e59439 100644 > --- a/arch/arm/include/asm/compiler.h > +++ b/arch/arm/include/asm/compiler.h > @@ -8,8 +8,21 @@ > * This string is meant to be concatenated with the inline asm string and > * will cause compilation to stop on mismatch. > * (for details, see gcc PR 15089) > + * For compatibility with clang, we have to specifically take the equivalence > + * of 'r11' <-> 'fp' and 'r12' <-> 'ip' into account as well. > */ > -#define __asmeq(x, y) ".ifnc " x "," y " ; .err ; .endif\n\t" > +#define __asmeq(x, y) \ > + ".ifnc " x "," y "; " \ > + ".ifnc " x y ",fpr11; " \ > + ".ifnc " x y ",r11fp; " \ > + ".ifnc " x y ",ipr12; " \ > + ".ifnc " x y ",r12ip; " \ > + ".err; " \ > + ".endif; " \ > + ".endif; " \ > + ".endif; " \ > + ".endif; " \ > + ".endif\n\t" > > > #endif /* __ASM_ARM_COMPILER_H */ >