On Sun, Mar 25, 2018 at 08:09:56PM +0200, Stefan Agner wrote: > As documented in GCC naked functions should only use Basic asm > syntax. The Extended asm or mixture of Basic asm and "C" code is > not guaranteed. Currently this works because it was hard coded > to follow and check GCC behavior for arguments and register > placement. > > Furthermore with clang using parameters in Extended asm in a > naked function is not supported: > arch/arm/firmware/trusted_foundations.c:47:10: error: parameter > references not allowed in naked functions > : "r" (type), "r" (arg1), "r" (arg2) > ^ > > Use a regular function to be more portable. This aligns also with > the other smc call implementations e.g. in qcom_scm-32.c and > bcm_kona_smc.c. > > Cc: Dmitry Osipenko <[email protected]> > Cc: Stephen Warren <[email protected]> > Cc: Thierry Reding <[email protected]> > Signed-off-by: Stefan Agner <[email protected]> > --- > Changes in v2: > - Keep stmfd/ldmfd to avoid potential ABI issues > > arch/arm/firmware/trusted_foundations.c | 14 +++++++++----- > 1 file changed, 9 insertions(+), 5 deletions(-) > > diff --git a/arch/arm/firmware/trusted_foundations.c > b/arch/arm/firmware/trusted_foundations.c > index 3fb1b5a1dce9..689e6565abfc 100644 > --- a/arch/arm/firmware/trusted_foundations.c > +++ b/arch/arm/firmware/trusted_foundations.c > @@ -31,21 +31,25 @@ > > static unsigned long cpu_boot_addr; > > -static void __naked tf_generic_smc(u32 type, u32 arg1, u32 arg2) > +static void tf_generic_smc(u32 type, u32 arg1, u32 arg2) > { > + register u32 r0 asm("r0") = type; > + register u32 r1 asm("r1") = arg1; > + register u32 r2 asm("r2") = arg2; > + > asm volatile( > ".arch_extension sec\n\t" > - "stmfd sp!, {r4 - r11, lr}\n\t" > + "stmfd sp!, {r4 - r11}\n\t" > __asmeq("%0", "r0") > __asmeq("%1", "r1") > __asmeq("%2", "r2") > "mov r3, #0\n\t" > "mov r4, #0\n\t" > "smc #0\n\t" > - "ldmfd sp!, {r4 - r11, pc}" > + "ldmfd sp!, {r4 - r11}\n\t" > : > - : "r" (type), "r" (arg1), "r" (arg2) > - : "memory"); > + : "r" (r0), "r" (r1), "r" (r2) > + : "memory", "r3", "r12", "lr"); > }
Does GCC try to inline this? It may just be better to switch to basic asm. We know that a naked function won't be inlined, and we already know (because we need the prologue/epilogue) what registers the 32-bit arguments will be in. -- RMK's Patch system: http://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line in suburbia: sync at 13.8Mbps down 630kbps up According to speedtest.net: 13Mbps down 490kbps up
