public inbox for linux-riscv@lists.infradead.org
 help / color / mirror / Atom feed
From: Sami Tolvanen <samitolvanen@google.com>
To: Paul Walmsley <paul.walmsley@sifive.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	 Albert Ou <aou@eecs.berkeley.edu>,
	Kees Cook <keescook@chromium.org>
Cc: Clement Leger <cleger@rivosinc.com>, Guo Ren <guoren@kernel.org>,
	 Deepak Gupta <debug@rivosinc.com>,
	Nathan Chancellor <nathan@kernel.org>,
	 Nick Desaulniers <ndesaulniers@google.com>,
	Fangrui Song <maskray@google.com>,
	 linux-riscv@lists.infradead.org, llvm@lists.linux.dev,
	 linux-kernel@vger.kernel.org,
	Sami Tolvanen <samitolvanen@google.com>
Subject: [PATCH v4 2/6] riscv: Deduplicate IRQ stack switching
Date: Wed, 27 Sep 2023 22:48:00 +0000	[thread overview]
Message-ID: <20230927224757.1154247-10-samitolvanen@google.com> (raw)
In-Reply-To: <20230927224757.1154247-8-samitolvanen@google.com>

With CONFIG_IRQ_STACKS, we switch to a separate per-CPU IRQ stack
before calling handle_riscv_irq or __do_softirq. We currently
have duplicate inline assembly snippets for stack switching in
both code paths. Now that we can access per-CPU variables in
assembly, implement call_on_irq_stack in assembly, and use that
instead of redundant inline assembly.

Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Guo Ren <guoren@kernel.org>
---
 arch/riscv/include/asm/asm.h       |  5 +++++
 arch/riscv/include/asm/irq_stack.h |  3 +++
 arch/riscv/kernel/asm-offsets.c    |  5 +++++
 arch/riscv/kernel/entry.S          | 30 +++++++++++++++++++++++++
 arch/riscv/kernel/irq.c            | 35 +++++++-----------------------
 arch/riscv/kernel/traps.c          | 32 ++++-----------------------
 6 files changed, 55 insertions(+), 55 deletions(-)

diff --git a/arch/riscv/include/asm/asm.h b/arch/riscv/include/asm/asm.h
index bfb4c26f113c..8e446be2d57c 100644
--- a/arch/riscv/include/asm/asm.h
+++ b/arch/riscv/include/asm/asm.h
@@ -104,6 +104,11 @@
 .endm
 #endif /* CONFIG_SMP */
 
+.macro load_per_cpu dst ptr tmp
+	asm_per_cpu \dst \ptr \tmp
+	REG_L \dst, 0(\dst)
+.endm
+
 	/* save all GPs except x1 ~ x5 */
 	.macro save_from_x6_to_x31
 	REG_S x6,  PT_T1(sp)
diff --git a/arch/riscv/include/asm/irq_stack.h b/arch/riscv/include/asm/irq_stack.h
index e4042d297580..6441ded3b0cf 100644
--- a/arch/riscv/include/asm/irq_stack.h
+++ b/arch/riscv/include/asm/irq_stack.h
@@ -12,6 +12,9 @@
 
 DECLARE_PER_CPU(ulong *, irq_stack_ptr);
 
+asmlinkage void call_on_irq_stack(struct pt_regs *regs,
+				  void (*func)(struct pt_regs *));
+
 #ifdef CONFIG_VMAP_STACK
 /*
  * To ensure that VMAP'd stack overflow detection works correctly, all VMAP'd
diff --git a/arch/riscv/kernel/asm-offsets.c b/arch/riscv/kernel/asm-offsets.c
index 9f535d5de33f..0af8860f9d68 100644
--- a/arch/riscv/kernel/asm-offsets.c
+++ b/arch/riscv/kernel/asm-offsets.c
@@ -14,6 +14,7 @@
 #include <asm/thread_info.h>
 #include <asm/ptrace.h>
 #include <asm/cpu_ops_sbi.h>
+#include <asm/stacktrace.h>
 #include <asm/suspend.h>
 
 void asm_offsets(void);
@@ -480,4 +481,8 @@ void asm_offsets(void)
 	OFFSET(KERNEL_MAP_VIRT_ADDR, kernel_mapping, virt_addr);
 	OFFSET(SBI_HART_BOOT_TASK_PTR_OFFSET, sbi_hart_boot_data, task_ptr);
 	OFFSET(SBI_HART_BOOT_STACK_PTR_OFFSET, sbi_hart_boot_data, stack_ptr);
+
+	DEFINE(STACKFRAME_SIZE_ON_STACK, ALIGN(sizeof(struct stackframe), STACK_ALIGN));
+	OFFSET(STACKFRAME_FP, stackframe, fp);
+	OFFSET(STACKFRAME_RA, stackframe, ra);
 }
diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S
index 3d11aa3af105..a306562636e4 100644
--- a/arch/riscv/kernel/entry.S
+++ b/arch/riscv/kernel/entry.S
@@ -218,6 +218,36 @@ SYM_CODE_START(ret_from_fork)
 	tail syscall_exit_to_user_mode
 SYM_CODE_END(ret_from_fork)
 
+#ifdef CONFIG_IRQ_STACKS
+/*
+ * void call_on_irq_stack(struct pt_regs *regs,
+ * 		          void (*func)(struct pt_regs *));
+ *
+ * Calls func(regs) using the per-CPU IRQ stack.
+ */
+SYM_FUNC_START(call_on_irq_stack)
+	/* Create a frame record to save ra and s0 (fp) */
+	addi	sp, sp, -STACKFRAME_SIZE_ON_STACK
+	REG_S	ra, STACKFRAME_RA(sp)
+	REG_S	s0, STACKFRAME_FP(sp)
+	addi	s0, sp, STACKFRAME_SIZE_ON_STACK
+
+	/* Switch to the per-CPU IRQ stack and call the handler */
+	load_per_cpu t0, irq_stack_ptr, t1
+	li	t1, IRQ_STACK_SIZE
+	add	sp, t0, t1
+	jalr	a1
+
+	/* Switch back to the thread stack and restore ra and s0 */
+	addi	sp, s0, -STACKFRAME_SIZE_ON_STACK
+	REG_L	ra, STACKFRAME_RA(sp)
+	REG_L	s0, STACKFRAME_FP(sp)
+	addi	sp, sp, STACKFRAME_SIZE_ON_STACK
+
+	ret
+SYM_FUNC_END(call_on_irq_stack)
+#endif /* CONFIG_IRQ_STACKS */
+
 /*
  * Integer register context switch
  * The callee-saved registers must be saved and restored.
diff --git a/arch/riscv/kernel/irq.c b/arch/riscv/kernel/irq.c
index a8efa053c4a5..95dafdcbd135 100644
--- a/arch/riscv/kernel/irq.c
+++ b/arch/riscv/kernel/irq.c
@@ -61,35 +61,16 @@ static void init_irq_stacks(void)
 #endif /* CONFIG_VMAP_STACK */
 
 #ifdef CONFIG_HAVE_SOFTIRQ_ON_OWN_STACK
+static void ___do_softirq(struct pt_regs *regs)
+{
+	__do_softirq();
+}
+
 void do_softirq_own_stack(void)
 {
-#ifdef CONFIG_IRQ_STACKS
-	if (on_thread_stack()) {
-		ulong *sp = per_cpu(irq_stack_ptr, smp_processor_id())
-					+ IRQ_STACK_SIZE/sizeof(ulong);
-		__asm__ __volatile(
-		"addi	sp, sp, -"RISCV_SZPTR  "\n"
-		REG_S"  ra, (sp)		\n"
-		"addi	sp, sp, -"RISCV_SZPTR  "\n"
-		REG_S"  s0, (sp)		\n"
-		"addi	s0, sp, 2*"RISCV_SZPTR "\n"
-		"move	sp, %[sp]		\n"
-		"call	__do_softirq		\n"
-		"addi	sp, s0, -2*"RISCV_SZPTR"\n"
-		REG_L"  s0, (sp)		\n"
-		"addi	sp, sp, "RISCV_SZPTR   "\n"
-		REG_L"  ra, (sp)		\n"
-		"addi	sp, sp, "RISCV_SZPTR   "\n"
-		:
-		: [sp] "r" (sp)
-		: "a0", "a1", "a2", "a3", "a4", "a5", "a6", "a7",
-		  "t0", "t1", "t2", "t3", "t4", "t5", "t6",
-#ifndef CONFIG_FRAME_POINTER
-		  "s0",
-#endif
-		  "memory");
-	} else
-#endif
+	if (on_thread_stack())
+		call_on_irq_stack(NULL, ___do_softirq);
+	else
 		__do_softirq();
 }
 #endif /* CONFIG_HAVE_SOFTIRQ_ON_OWN_STACK */
diff --git a/arch/riscv/kernel/traps.c b/arch/riscv/kernel/traps.c
index 0063a195deca..cda6dcdb0376 100644
--- a/arch/riscv/kernel/traps.c
+++ b/arch/riscv/kernel/traps.c
@@ -352,34 +352,10 @@ static void noinstr handle_riscv_irq(struct pt_regs *regs)
 asmlinkage void noinstr do_irq(struct pt_regs *regs)
 {
 	irqentry_state_t state = irqentry_enter(regs);
-#ifdef CONFIG_IRQ_STACKS
-	if (on_thread_stack()) {
-		ulong *sp = per_cpu(irq_stack_ptr, smp_processor_id())
-					+ IRQ_STACK_SIZE/sizeof(ulong);
-		__asm__ __volatile(
-		"addi	sp, sp, -"RISCV_SZPTR  "\n"
-		REG_S"  ra, (sp)		\n"
-		"addi	sp, sp, -"RISCV_SZPTR  "\n"
-		REG_S"  s0, (sp)		\n"
-		"addi	s0, sp, 2*"RISCV_SZPTR "\n"
-		"move	sp, %[sp]		\n"
-		"move	a0, %[regs]		\n"
-		"call	handle_riscv_irq	\n"
-		"addi	sp, s0, -2*"RISCV_SZPTR"\n"
-		REG_L"  s0, (sp)		\n"
-		"addi	sp, sp, "RISCV_SZPTR   "\n"
-		REG_L"  ra, (sp)		\n"
-		"addi	sp, sp, "RISCV_SZPTR   "\n"
-		:
-		: [sp] "r" (sp), [regs] "r" (regs)
-		: "a0", "a1", "a2", "a3", "a4", "a5", "a6", "a7",
-		  "t0", "t1", "t2", "t3", "t4", "t5", "t6",
-#ifndef CONFIG_FRAME_POINTER
-		  "s0",
-#endif
-		  "memory");
-	} else
-#endif
+
+	if (IS_ENABLED(CONFIG_IRQ_STACKS) && on_thread_stack())
+		call_on_irq_stack(regs, handle_riscv_irq);
+	else
 		handle_riscv_irq(regs);
 
 	irqentry_exit(regs, state);
-- 
2.42.0.515.g380fc7ccd1-goog


_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv

  parent reply	other threads:[~2023-09-27 22:48 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-09-27 22:47 [PATCH v4 0/6] riscv: SCS support Sami Tolvanen
2023-09-27 22:47 ` [PATCH v4 1/6] riscv: VMAP_STACK overflow detection thread-safe Sami Tolvanen
2023-09-27 22:48 ` Sami Tolvanen [this message]
2023-09-27 22:48 ` [PATCH v4 3/6] riscv: Move global pointer loading to a macro Sami Tolvanen
2023-09-27 22:48 ` [PATCH v4 4/6] riscv: Implement Shadow Call Stack Sami Tolvanen
2023-09-27 22:48 ` [PATCH v4 5/6] riscv: Use separate IRQ shadow call stacks Sami Tolvanen
2023-09-27 22:48 ` [PATCH v4 6/6] lkdtm: Fix CFI_BACKWARD on RISC-V Sami Tolvanen
2023-11-02 20:20 ` [PATCH v4 0/6] riscv: SCS support patchwork-bot+linux-riscv

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20230927224757.1154247-10-samitolvanen@google.com \
    --to=samitolvanen@google.com \
    --cc=aou@eecs.berkeley.edu \
    --cc=cleger@rivosinc.com \
    --cc=debug@rivosinc.com \
    --cc=guoren@kernel.org \
    --cc=keescook@chromium.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-riscv@lists.infradead.org \
    --cc=llvm@lists.linux.dev \
    --cc=maskray@google.com \
    --cc=nathan@kernel.org \
    --cc=ndesaulniers@google.com \
    --cc=palmer@dabbelt.com \
    --cc=paul.walmsley@sifive.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox