Messages in this thread | | | From | Rémi Denis-Courmont <> | Subject | Re: [PATCH 1/3] RISC-V: Framework for vendor extensions | Date | Thu, 06 Jul 2023 23:04:24 +0300 |
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Le torstaina 6. heinäkuuta 2023, 22.44.07 EEST Charlie Jenkins a écrit : > On Thu, Jul 06, 2023 at 07:29:37PM +0300, Rémi Denis-Courmont wrote: > > Le torstaina 6. heinäkuuta 2023, 6.30.17 EEST Charlie Jenkins a écrit : > > > Create Kconfig files, Makefiles, and functions to enable vendors to > > > provide information via the riscv_hwprobe syscall about which vendor > > > extensions are available. > > > > > > Signed-off-by: Charlie Jenkins <charlie@rivosinc.com> > > > --- > > > > > > arch/riscv/Kbuild | 1 + > > > arch/riscv/Kconfig | 1 + > > > arch/riscv/Kconfig.vendor | 3 +++ > > > arch/riscv/include/asm/hwprobe.h | 1 + > > > arch/riscv/kernel/sys_riscv.c | 40 > > > > > > ++++++++++++++++++++++++++++++++--- > > > arch/riscv/vendor_extensions/Makefile | > > > > > > 3 +++ > > > 6 files changed, 46 insertions(+), 3 deletions(-) > > > > > > diff --git a/arch/riscv/Kbuild b/arch/riscv/Kbuild > > > index afa83e307a2e..bea38010d9db 100644 > > > --- a/arch/riscv/Kbuild > > > +++ b/arch/riscv/Kbuild > > > @@ -3,6 +3,7 @@ > > > > > > obj-y += kernel/ mm/ net/ > > > obj-$(CONFIG_BUILTIN_DTB) += boot/dts/ > > > obj-y += errata/ > > > > > > +obj-y += vendor_extensions/ > > > > > > obj-$(CONFIG_KVM) += kvm/ > > > > > > obj-$(CONFIG_ARCH_HAS_KEXEC_PURGATORY) += purgatory/ > > > > > > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig > > > index c1505c7729ec..19404ede0ee3 100644 > > > --- a/arch/riscv/Kconfig > > > +++ b/arch/riscv/Kconfig > > > @@ -276,6 +276,7 @@ config AS_HAS_OPTION_ARCH > > > > > > source "arch/riscv/Kconfig.socs" > > > source "arch/riscv/Kconfig.errata" > > > > > > +source "arch/riscv/Kconfig.vendor" > > > > > > menu "Platform type" > > > > > > diff --git a/arch/riscv/Kconfig.vendor b/arch/riscv/Kconfig.vendor > > > new file mode 100644 > > > index 000000000000..213ac3e6fed5 > > > --- /dev/null > > > +++ b/arch/riscv/Kconfig.vendor > > > @@ -0,0 +1,3 @@ > > > +menu "Vendor extensions selection" > > > + > > > +endmenu # "Vendor extensions selection" > > > diff --git a/arch/riscv/include/asm/hwprobe.h > > > b/arch/riscv/include/asm/hwprobe.h index 78936f4ff513..fadb38b83243 > > > 100644 > > > --- a/arch/riscv/include/asm/hwprobe.h > > > +++ b/arch/riscv/include/asm/hwprobe.h > > > @@ -9,5 +9,6 @@ > > > > > > #include <uapi/asm/hwprobe.h> > > > > > > #define RISCV_HWPROBE_MAX_KEY 5 > > > > > > +#define RISCV_HWPROBE_VENDOR_EXTENSION_SPACE (UL(1)<<63) > > > > Isn't this UB on 32-bit RISC-V ? > > Hmm, yeah it would be, but the hwprobe syscall is based on a 64 bit key > using the __s64 type. There could be an alternative vendor space at the > top of 32-bits for those machines.
Key values inside the struct are 64-bit even on RV32, but your key definition here is 32-bit. That can't work.
Plus this needs to be defined under uapi/ as the rest of the hwprobe constants.
And then, even on RV64, 1UL << 63 is not a valid signed constant. Kernel code might tolerate it, but that will most likely cause warnings or errors in the potentially stricter compilation environments of user-space code.
> > > #endif > > > > > > diff --git a/arch/riscv/kernel/sys_riscv.c > > > b/arch/riscv/kernel/sys_riscv.c > > > index 26ef5526bfb4..2351a5f7b8b1 100644 > > > --- a/arch/riscv/kernel/sys_riscv.c > > > +++ b/arch/riscv/kernel/sys_riscv.c > > > @@ -188,9 +188,35 @@ static u64 hwprobe_misaligned(const struct cpumask > > > *cpus) return perf; > > > > > > } > > > > > > +static int hwprobe_vendor(__u64 mvendorid, struct riscv_hwprobe *pair, > > > + const struct cpumask *cpus) > > > +{ > > > + switch (mvendorid) { > > > + default: > > > + return -1; > > > + } > > > + > > > + return 0; > > > +} > > > + > > > > > > static void hwprobe_one_pair(struct riscv_hwprobe *pair, > > > > > > const struct cpumask *cpus) > > > > > > { > > > > > > + int err; > > > + > > > + if (((unsigned long) pair->key) >= > > > > RISCV_HWPROBE_VENDOR_EXTENSION_SPACE) { > > > > > + struct riscv_hwprobe mvendorid = { > > > + .key = RISCV_HWPROBE_KEY_MVENDORID, > > > + .value = 0 > > > + }; > > > + > > > + hwprobe_arch_id(&mvendorid, cpus); > > > + if (mvendorid.value != -1ULL) > > > + err = hwprobe_vendor(mvendorid.value, pair, > > > > cpus); > > > > > + else > > > + err = -1; > > > + } > > > + > > > > > > switch (pair->key) { > > > case RISCV_HWPROBE_KEY_MVENDORID: > > > > > > case RISCV_HWPROBE_KEY_MARCHID: > > > @@ -217,13 +243,21 @@ static void hwprobe_one_pair(struct riscv_hwprobe > > > *pair, > > > > > > /* > > > > > > * For forward compatibility, unknown keys don't fail the whole > > > > > > - * call, but get their element key set to -1 and value set to 0 > > > - * indicating they're unrecognized. > > > + * call, instead an error is raised to indicate the element key > > > + * is unrecognized. > > > > > > */ > > > > > > default: > > > + err = -1; > > > + break; > > > + } > > > + > > > + /* > > > + * Setting the element key to -1 and value to 0 indicates that > > > + * hwprobe was unable to find the requested key. > > > + */ > > > + if (err != 0) { > > > > > > pair->key = -1; > > > pair->value = 0; > > > > > > - break; > > > > > > } > > > > > > } > > > > > > diff --git a/arch/riscv/vendor_extensions/Makefile > > > b/arch/riscv/vendor_extensions/Makefile new file mode 100644 > > > index 000000000000..e815895e9372 > > > --- /dev/null > > > +++ b/arch/riscv/vendor_extensions/Makefile > > > @@ -0,0 +1,3 @@ > > > +ifdef CONFIG_RELOCATABLE > > > +KBUILD_CFLAGS += -fno-pie > > > +endif
-- 雷米‧德尼-库尔蒙 http://www.remlab.net/
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