On 8/7/24 10:06, Deepak Gupta wrote:
Add zicfilp support in VDSO. VDSO functions need lpad instruction so that userspace could call this function when landing pad extension is enabled. This solution only works when toolchain always use landing pad label 1.
Well, no, the lpad insns *could* use imm=0. Why would the toolchain always use label 1? Much more explanation is required here.
+/* GNU_PROPERTY_RISCV64_* macros from elf.h for use in asm code. */ +#define FEATURE_1_AND 0xc0000000 + +#define GNU_PROPERTY(type, value) \ + .section .note.gnu.property, "a"; \ + .p2align 3; \ + .word 4; \ + .word 16; \ + .word 5; \ + .asciz "GNU"; \ + .word type; \ + .word 4; \ + .word value; \ + .word 0; \ + .text + +/* Add GNU property note with the supported features to all asm code + where sysdep.h is included. */ +#undef __VALUE_FOR_FEATURE_1_AND +#if defined (__riscv_zicfilp) || defined (__riscv_zicfiss) +# if defined (__riscv_zicfilp) +# if defined (__riscv_zicfiss)
Why are you checking __riscv_* symbols, for when the toolchain has these features enabled on the command-line? This is the kind of feature you want enabled always.
+#ifdef __riscv_zicfilp +# define LPAD lpad 1 +#else +# define LPAD +#endif
Here, especially, you should be using ".insn", not omitting the lpad insn. r~
