From: Guo Ren <guoren@linux.alibaba.com>
Date: Tue, 17 Dec 2024 01:39:10 +0000 (-0500)
Subject: riscv: Implement smp_cond_load8/16() with Zawrs
X-Git-Tag: v6.15-rc1~18^2~3^2~22
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=d9708b1931fc0ebb21cd94a56283d09222847749;p=thirdparty%2Fkernel%2Flinux.git

riscv: Implement smp_cond_load8/16() with Zawrs

RISC-V code uses the queued spinlock implementation, which calls
the macros smp_cond_load_acquire for one byte. So, complement the
implementation of byte and halfword versions.

Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Signed-off-by: Guo Ren <guoren@kernel.org>
Cc: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Link: https://lore.kernel.org/r/20241217013910.1039923-1-guoren@kernel.org
Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
---

diff --git a/arch/riscv/include/asm/cmpxchg.h b/arch/riscv/include/asm/cmpxchg.h
index 427c41dde6431..2ec119eb147bb 100644
--- a/arch/riscv/include/asm/cmpxchg.h
+++ b/arch/riscv/include/asm/cmpxchg.h
@@ -365,16 +365,48 @@ static __always_inline void __cmpwait(volatile void *ptr,
 {
 	unsigned long tmp;
 
+	u32 *__ptr32b;
+	ulong __s, __val, __mask;
+
 	asm goto(ALTERNATIVE("j %l[no_zawrs]", "nop",
 			     0, RISCV_ISA_EXT_ZAWRS, 1)
 		 : : : : no_zawrs);
 
 	switch (size) {
 	case 1:
-		fallthrough;
+		__ptr32b = (u32 *)((ulong)(ptr) & ~0x3);
+		__s = ((ulong)(ptr) & 0x3) * BITS_PER_BYTE;
+		__val = val << __s;
+		__mask = 0xff << __s;
+
+		asm volatile(
+		"	lr.w	%0, %1\n"
+		"	and	%0, %0, %3\n"
+		"	xor	%0, %0, %2\n"
+		"	bnez	%0, 1f\n"
+			ZAWRS_WRS_NTO "\n"
+		"1:"
+		: "=&r" (tmp), "+A" (*(__ptr32b))
+		: "r" (__val), "r" (__mask)
+		: "memory");
+		break;
 	case 2:
-		/* RISC-V doesn't have lr instructions on byte and half-word. */
-		goto no_zawrs;
+		__ptr32b = (u32 *)((ulong)(ptr) & ~0x3);
+		__s = ((ulong)(ptr) & 0x2) * BITS_PER_BYTE;
+		__val = val << __s;
+		__mask = 0xffff << __s;
+
+		asm volatile(
+		"	lr.w	%0, %1\n"
+		"	and	%0, %0, %3\n"
+		"	xor	%0, %0, %2\n"
+		"	bnez	%0, 1f\n"
+			ZAWRS_WRS_NTO "\n"
+		"1:"
+		: "=&r" (tmp), "+A" (*(__ptr32b))
+		: "r" (__val), "r" (__mask)
+		: "memory");
+		break;
 	case 4:
 		asm volatile(
 		"	lr.w	%0, %1\n"