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Message-Id: <20240826105737.106879-1-alexghiti@rivosinc.com>
Date: Mon, 26 Aug 2024 12:57:37 +0200
From: Alexandre Ghiti <alexghiti@...osinc.com>
To: Paul Walmsley <paul.walmsley@...ive.com>,
	Palmer Dabbelt <palmer@...belt.com>,
	Albert Ou <aou@...s.berkeley.edu>,
	Guo Ren <guoren@...nel.org>,
	Heiko Stuebner <heiko@...ech.de>,
	Philipp Tomsich <philipp.tomsich@...ll.eu>,
	linux-riscv@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Cc: Alexandre Ghiti <alexghiti@...osinc.com>
Subject: [PATCH -fixes] riscv: Fix RISCV_ALTERNATIVE_EARLY

RISCV_ALTERNATIVE_EARLY will issue sbi_ecall() very early in the boot
process, before the first memory mapping is setup so we can't have any
instrumentation happening here.

In addition, when the kernel is relocatable, we must also not issue any
relocation this early since they would have been patched virtually only.

So, instead of disabling instrumentation for the whole kernel/sbi.c file
and compiling it with -fno-pie, simply move __sbi_ecall() and
__sbi_base_ecall() into their own file where this is fixed.

Fixes: 1745cfafebdf ("riscv: don't use global static vars to store alternative data")
Signed-off-by: Alexandre Ghiti <alexghiti@...osinc.com>
---
 arch/riscv/include/asm/sbi.h  |  2 ++
 arch/riscv/kernel/Makefile    |  6 ++++-
 arch/riscv/kernel/sbi.c       | 44 --------------------------------
 arch/riscv/kernel/sbi_ecall.c | 48 +++++++++++++++++++++++++++++++++++
 4 files changed, 55 insertions(+), 45 deletions(-)
 create mode 100644 arch/riscv/kernel/sbi_ecall.c

diff --git a/arch/riscv/include/asm/sbi.h b/arch/riscv/include/asm/sbi.h
index 7cffd4ffecd0..5843a10b380e 100644
--- a/arch/riscv/include/asm/sbi.h
+++ b/arch/riscv/include/asm/sbi.h
@@ -9,6 +9,7 @@
 
 #include <linux/types.h>
 #include <linux/cpumask.h>
+#include <linux/jump_label.h>
 
 #ifdef CONFIG_RISCV_SBI
 enum sbi_ext_id {
@@ -304,6 +305,7 @@ struct sbiret {
 };
 
 void sbi_init(void);
+long __sbi_base_ecall(int fid);
 struct sbiret __sbi_ecall(unsigned long arg0, unsigned long arg1,
 			  unsigned long arg2, unsigned long arg3,
 			  unsigned long arg4, unsigned long arg5,
diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile
index 06d407f1b30b..7f88cc4931f5 100644
--- a/arch/riscv/kernel/Makefile
+++ b/arch/riscv/kernel/Makefile
@@ -20,17 +20,21 @@ endif
 ifdef CONFIG_RISCV_ALTERNATIVE_EARLY
 CFLAGS_alternative.o := -mcmodel=medany
 CFLAGS_cpufeature.o := -mcmodel=medany
+CFLAGS_sbi_ecall.o := -mcmodel=medany
 ifdef CONFIG_FTRACE
 CFLAGS_REMOVE_alternative.o = $(CC_FLAGS_FTRACE)
 CFLAGS_REMOVE_cpufeature.o = $(CC_FLAGS_FTRACE)
+CFLAGS_REMOVE_sbi_ecall.o = $(CC_FLAGS_FTRACE)
 endif
 ifdef CONFIG_RELOCATABLE
 CFLAGS_alternative.o += -fno-pie
 CFLAGS_cpufeature.o += -fno-pie
+CFLAGS_sbi_ecall.o += -fno-pie
 endif
 ifdef CONFIG_KASAN
 KASAN_SANITIZE_alternative.o := n
 KASAN_SANITIZE_cpufeature.o := n
+KASAN_SANITIZE_sbi_ecall.o := n
 endif
 endif
 
@@ -88,7 +92,7 @@ obj-$(CONFIG_DYNAMIC_FTRACE)	+= mcount-dyn.o
 
 obj-$(CONFIG_PERF_EVENTS)	+= perf_callchain.o
 obj-$(CONFIG_HAVE_PERF_REGS)	+= perf_regs.o
-obj-$(CONFIG_RISCV_SBI)		+= sbi.o
+obj-$(CONFIG_RISCV_SBI)		+= sbi.o sbi_ecall.o
 ifeq ($(CONFIG_RISCV_SBI), y)
 obj-$(CONFIG_SMP)		+= sbi-ipi.o
 obj-$(CONFIG_SMP) += cpu_ops_sbi.o
diff --git a/arch/riscv/kernel/sbi.c b/arch/riscv/kernel/sbi.c
index 837bdab2601b..ace9e2f59c41 100644
--- a/arch/riscv/kernel/sbi.c
+++ b/arch/riscv/kernel/sbi.c
@@ -14,9 +14,6 @@
 #include <asm/smp.h>
 #include <asm/tlbflush.h>
 
-#define CREATE_TRACE_POINTS
-#include <asm/trace.h>
-
 /* default SBI version is 0.1 */
 unsigned long sbi_spec_version __ro_after_init = SBI_SPEC_VERSION_DEFAULT;
 EXPORT_SYMBOL(sbi_spec_version);
@@ -27,36 +24,6 @@ static int (*__sbi_rfence)(int fid, const struct cpumask *cpu_mask,
 			   unsigned long start, unsigned long size,
 			   unsigned long arg4, unsigned long arg5) __ro_after_init;
 
-struct sbiret __sbi_ecall(unsigned long arg0, unsigned long arg1,
-			  unsigned long arg2, unsigned long arg3,
-			  unsigned long arg4, unsigned long arg5,
-			  int fid, int ext)
-{
-	struct sbiret ret;
-
-	trace_sbi_call(ext, fid);
-
-	register uintptr_t a0 asm ("a0") = (uintptr_t)(arg0);
-	register uintptr_t a1 asm ("a1") = (uintptr_t)(arg1);
-	register uintptr_t a2 asm ("a2") = (uintptr_t)(arg2);
-	register uintptr_t a3 asm ("a3") = (uintptr_t)(arg3);
-	register uintptr_t a4 asm ("a4") = (uintptr_t)(arg4);
-	register uintptr_t a5 asm ("a5") = (uintptr_t)(arg5);
-	register uintptr_t a6 asm ("a6") = (uintptr_t)(fid);
-	register uintptr_t a7 asm ("a7") = (uintptr_t)(ext);
-	asm volatile ("ecall"
-		      : "+r" (a0), "+r" (a1)
-		      : "r" (a2), "r" (a3), "r" (a4), "r" (a5), "r" (a6), "r" (a7)
-		      : "memory");
-	ret.error = a0;
-	ret.value = a1;
-
-	trace_sbi_return(ext, ret.error, ret.value);
-
-	return ret;
-}
-EXPORT_SYMBOL(__sbi_ecall);
-
 int sbi_err_map_linux_errno(int err)
 {
 	switch (err) {
@@ -535,17 +502,6 @@ long sbi_probe_extension(int extid)
 }
 EXPORT_SYMBOL(sbi_probe_extension);
 
-static long __sbi_base_ecall(int fid)
-{
-	struct sbiret ret;
-
-	ret = sbi_ecall(SBI_EXT_BASE, fid, 0, 0, 0, 0, 0, 0);
-	if (!ret.error)
-		return ret.value;
-	else
-		return sbi_err_map_linux_errno(ret.error);
-}
-
 static inline long sbi_get_spec_version(void)
 {
 	return __sbi_base_ecall(SBI_EXT_BASE_GET_SPEC_VERSION);
diff --git a/arch/riscv/kernel/sbi_ecall.c b/arch/riscv/kernel/sbi_ecall.c
new file mode 100644
index 000000000000..24aabb4fbde3
--- /dev/null
+++ b/arch/riscv/kernel/sbi_ecall.c
@@ -0,0 +1,48 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2024 Rivos Inc. */
+
+#include <asm/sbi.h>
+#define CREATE_TRACE_POINTS
+#include <asm/trace.h>
+
+long __sbi_base_ecall(int fid)
+{
+	struct sbiret ret;
+
+	ret = sbi_ecall(SBI_EXT_BASE, fid, 0, 0, 0, 0, 0, 0);
+	if (!ret.error)
+		return ret.value;
+	else
+		return sbi_err_map_linux_errno(ret.error);
+}
+EXPORT_SYMBOL(__sbi_base_ecall);
+
+struct sbiret __sbi_ecall(unsigned long arg0, unsigned long arg1,
+			  unsigned long arg2, unsigned long arg3,
+			  unsigned long arg4, unsigned long arg5,
+			  int fid, int ext)
+{
+	struct sbiret ret;
+
+	trace_sbi_call(ext, fid);
+
+	register uintptr_t a0 asm ("a0") = (uintptr_t)(arg0);
+	register uintptr_t a1 asm ("a1") = (uintptr_t)(arg1);
+	register uintptr_t a2 asm ("a2") = (uintptr_t)(arg2);
+	register uintptr_t a3 asm ("a3") = (uintptr_t)(arg3);
+	register uintptr_t a4 asm ("a4") = (uintptr_t)(arg4);
+	register uintptr_t a5 asm ("a5") = (uintptr_t)(arg5);
+	register uintptr_t a6 asm ("a6") = (uintptr_t)(fid);
+	register uintptr_t a7 asm ("a7") = (uintptr_t)(ext);
+	asm volatile ("ecall"
+		       : "+r" (a0), "+r" (a1)
+		       : "r" (a2), "r" (a3), "r" (a4), "r" (a5), "r" (a6), "r" (a7)
+		       : "memory");
+	ret.error = a0;
+	ret.value = a1;
+
+	trace_sbi_return(ext, ret.error, ret.value);
+
+	return ret;
+}
+EXPORT_SYMBOL(__sbi_ecall);
-- 
2.39.2


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