Hi Radim,
On 06/05/2025 12:10, Radim Krčmář wrote:
[Ah, I missed v13 and v14, feel free to Cc me on next versions.]
2025-05-02T16:30:36-07:00, Deepak Gupta debug@rivosinc.com:
diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S @@ -91,6 +91,32 @@ +.macro save_userssp tmp, status
- ALTERNATIVE("nops(4)",
__stringify( \andi \tmp, \status, SR_SPP; \bnez \tmp, skip_ssp_save; \csrrw \tmp, CSR_SSP, x0; \REG_S \tmp, TASK_TI_USER_SSP(tp); \skip_ssp_save:),0,RISCV_ISA_EXT_ZICFISS,CONFIG_RISCV_USER_CFI)+.endm
+.macro restore_userssp tmp
- ALTERNATIVE("nops(2)",
__stringify( \REG_L \tmp, TASK_TI_USER_SSP(tp); \csrw CSR_SSP, \tmp),0,RISCV_ISA_EXT_ZICFISS,CONFIG_RISCV_USER_CFI)+.endm
Do we need to emit the nops when CONFIG_RISCV_USER_CFI isn't selected?
(Why not put #ifdef CONFIG_RISCV_USER_CFI around the ALTERNATIVES?)
The alternatives are used to create a generic kernel that contains the code for a large number of extensions and only enable it at runtime depending on the platform capabilities. This way distros can ship a single kernel that works on all platforms.
Thanks for your reviews on this series,
Alex
Thanks.
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