From: Jerome Forissier Date: Fri, 18 Apr 2025 14:09:31 +0000 (+0200) Subject: riscv: add initjmp() X-Git-Tag: v2025.07-rc1~32^2~14 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3691328ef69555148962654e7f834fd0b5273fcb;p=pandora-u-boot.git riscv: add initjmp() Implement initjmp() for RISC-V, a non-standard extension to setjmp()/ longjmp() allowing to initialize a jump buffer with a function pointer and a stack pointer. This will be useful to later introduce threads. With this new function it becomes possible to longjmp() to a particular function pointer (rather than to a point previously reached during program execution as is the case with setjmp()), and with a custom stack. Both things are needed to spin off a new thread. Then the usual setjmp()/longjmp() pair is enough to save and restore a context, i.e., switch thread. Signed-off-by: Jerome Forissier --- diff --git a/arch/Kconfig b/arch/Kconfig index 7a3141e92b3..aa60c5ff03c 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -153,6 +153,7 @@ config RISCV bool "RISC-V architecture" select CREATE_ARCH_SYMLINK select HAVE_SETJMP + select HAVE_INITJMP select SUPPORT_ACPI select SUPPORT_LITTLE_ENDIAN select SUPPORT_OF_CONTROL diff --git a/arch/riscv/lib/setjmp.S b/arch/riscv/lib/setjmp.S index 99d6195827e..9e1f3d5749b 100644 --- a/arch/riscv/lib/setjmp.S +++ b/arch/riscv/lib/setjmp.S @@ -59,3 +59,14 @@ ENTRY(longjmp) ret ENDPROC(longjmp) .popsection + +.pushsection .text.initjmp, "ax" +ENTRY(initjmp) + /* a1: entry point address, a2: stack base, a3: stack size */ + add a2, a2, a3 + STORE_IDX(a1, 12) + STORE_IDX(a2, 13) + li a0, 0 + ret +ENDPROC(initjmp) +.popsection