linux-kernel - [v6 PATCH] RISC-V: Remove unsupported isa string info print

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Message-Id: <20191001002318.7515-1-atish.patra@wdc.com>
Date:   Mon, 30 Sep 2019 17:23:18 -0700
From:   Atish Patra <atish.patra@....com>
To:     linux-kernel@...r.kernel.org
Cc:     Atish Patra <atish.patra@....com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Anup Patel <anup@...infault.org>,
        Johan Hovold <johan@...nel.org>,
        linux-riscv@...ts.infradead.org,
        Palmer Dabbelt <palmer@...ive.com>,
        Paul Walmsley <paul.walmsley@...ive.com>, hch@...radead.org
Subject: [v6 PATCH] RISC-V: Remove unsupported isa string info print

/proc/cpuinfo should just print all the isa string as an information
instead of determining what is supported or not. ELF hwcap can be
used by the userspace to figure out that.

Simplify the isa string printing by removing the unsupported isa string
print and all related code.

The relevant discussion can be found at
http://lists.infradead.org/pipermail/linux-riscv/2019-September/006702.html

Signed-off-by: Atish Patra <atish.patra@....com>
---
 arch/riscv/kernel/cpu.c | 35 ++++-------------------------------
 1 file changed, 4 insertions(+), 31 deletions(-)

diff --git a/arch/riscv/kernel/cpu.c b/arch/riscv/kernel/cpu.c
index 7da3c6a93abd..9486c426af86 100644
--- a/arch/riscv/kernel/cpu.c
+++ b/arch/riscv/kernel/cpu.c
@@ -48,49 +48,22 @@ int riscv_of_processor_hartid(struct device_node *node)
 
 static void print_isa(struct seq_file *f, const char *orig_isa)
 {
-	static const char *ext = "mafdcsu";
-	const char *isa = orig_isa;
-	const char *e;
-
 	/*
 	 * Linux doesn't support rv32e or rv128i, and we only support booting
 	 * kernels on harts with the same ISA that the kernel is compiled for.
 	 */
 #if defined(CONFIG_32BIT)
-	if (strncmp(isa, "rv32i", 5) != 0)
+	if (strncmp(orig_isa, "rv32i", 5) != 0)
 		return;
 #elif defined(CONFIG_64BIT)
-	if (strncmp(isa, "rv64i", 5) != 0)
+	if (strncmp(orig_isa, "rv64i", 5) != 0)
 		return;
 #endif
 
-	/* Print the base ISA, as we already know it's legal. */
+	/* Print the entire ISA as it is */
 	seq_puts(f, "isa\t\t: ");
-	seq_write(f, isa, 5);
-	isa += 5;
-
-	/*
-	 * Check the rest of the ISA string for valid extensions, printing those
-	 * we find.  RISC-V ISA strings define an order, so we only print the
-	 * extension bits when they're in order. Hide the supervisor (S)
-	 * extension from userspace as it's not accessible from there.
-	 */
-	for (e = ext; *e != '\0'; ++e) {
-		if (isa[0] == e[0]) {
-			if (isa[0] != 's')
-				seq_write(f, isa, 1);
-
-			isa++;
-		}
-	}
+	seq_write(f, orig_isa, strlen(orig_isa));
 	seq_puts(f, "\n");
-
-	/*
-	 * If we were given an unsupported ISA in the device tree then print
-	 * a bit of info describing what went wrong.
-	 */
-	if (isa[0] != '\0')
-		pr_info("unsupported ISA \"%s\" in device tree\n", orig_isa);
 }
 
 static void print_mmu(struct seq_file *f, const char *mmu_type)
-- 
2.21.0