linux-kernel - [RFC PATCH 04/12] riscv: update asm call sites with label setup

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Date: Mon,  8 Apr 2024 23:10:35 -0700
From: Deepak Gupta <debug@...osinc.com>
To: linux-riscv@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	llvm@...ts.linux.dev
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Subject: [RFC PATCH 04/12] riscv: update asm call sites with label setup

All call sites written in asm which will be converted to indirect call
form, they need to setup label register (t2/x7) with correct label.

Currently kernel is enabled with consant label of 0x1 for all functions.
Thus label is setup with 0x1 at call site. Eventually when hash over
function signature based label is adopted, such callsites in asm needs
to b updated as well. We need better scheme for that (some macro)

Signed-off-by: Deepak Gupta <debug@...osinc.com>
---
 arch/riscv/kernel/entry.S   | 2 ++
 arch/riscv/kernel/head.S    | 1 +
 arch/riscv/lib/clear_page.S | 1 +
 3 files changed, 4 insertions(+)

diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S
index be07355b9eff..a35050a3e0ea 100644
--- a/arch/riscv/kernel/entry.S
+++ b/arch/riscv/kernel/entry.S
@@ -219,6 +219,7 @@ SYM_CODE_START_LOCAL(handle_kernel_stack_overflow)
 	REG_S s4, PT_CAUSE(sp)
 	REG_S s5, PT_TP(sp)
 	move a0, sp
+	lui t2,0x1
 	tail handle_bad_stack
 SYM_CODE_END(handle_kernel_stack_overflow)
 ASM_NOKPROBE(handle_kernel_stack_overflow)
@@ -258,6 +259,7 @@ SYM_FUNC_START(call_on_irq_stack)
 	load_per_cpu t0, irq_stack_ptr, t1
 	li	t1, IRQ_STACK_SIZE
 	add	sp, t0, t1
+	lui t2, 0x1
 	jalr	a1
 
 	/* Switch back to the thread shadow call stack */
diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S
index 4236a69c35cb..6c311517c3b5 100644
--- a/arch/riscv/kernel/head.S
+++ b/arch/riscv/kernel/head.S
@@ -165,6 +165,7 @@ secondary_start_sbi:
 #endif
 	call .Lsetup_trap_vector
 	scs_load_current
+	lui t2, 0x1
 	tail smp_callin
 #endif /* CONFIG_SMP */
 
diff --git a/arch/riscv/lib/clear_page.S b/arch/riscv/lib/clear_page.S
index 20ff03f5b0f2..16e63ea91baa 100644
--- a/arch/riscv/lib/clear_page.S
+++ b/arch/riscv/lib/clear_page.S
@@ -69,6 +69,7 @@ SYM_FUNC_START(clear_page)
 	ret
 .Lno_zicboz:
 	li	a1, 0
+	lui t2, 0x1
 	tail	__memset
 SYM_FUNC_END(clear_page)
 EXPORT_SYMBOL(clear_page)
-- 
2.43.2