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 <de...@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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