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authorPalmer Dabbelt <palmer@sifive.com>2018-10-02 12:14:56 -0700
committerPalmer Dabbelt <palmer@sifive.com>2018-10-22 17:03:35 -0700
commit19ccf29bb18f08a4583aa899a8cc8c11e5ea85a6 (patch)
treee8dade2d43c99190dfe9c58a278790a4b034b527 /arch/riscv
parent566d6c428eadf9dc06df8b2195dff58d9a97c9e6 (diff)
downloadlinux-19ccf29bb18f08a4583aa899a8cc8c11e5ea85a6.tar.bz2
RISC-V: Filter ISA and MMU values in cpuinfo
We shouldn't be directly passing device tree values to userspace, both because there could be mistakes in device trees and because the kernel doesn't support arbitrary ISAs. Signed-off-by: Palmer Dabbelt <palmer@sifive.com> [Atish: checkpatch fix and code comment formatting update] Signed-off-by: Atish Patra <atish.patra@wdc.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
Diffstat (limited to 'arch/riscv')
-rw-r--r--arch/riscv/kernel/cpu.c68
1 files changed, 61 insertions, 7 deletions
diff --git a/arch/riscv/kernel/cpu.c b/arch/riscv/kernel/cpu.c
index ca6c81e54e37..1c0bf6620e65 100644
--- a/arch/riscv/kernel/cpu.c
+++ b/arch/riscv/kernel/cpu.c
@@ -58,6 +58,63 @@ int riscv_of_processor_hart(struct device_node *node)
#ifdef CONFIG_PROC_FS
+static void print_isa(struct seq_file *f, const char *orig_isa)
+{
+ static const char *ext = "mafdc";
+ 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)
+ return;
+#elif defined(CONFIG_64BIT)
+ if (strncmp(isa, "rv64i", 5) != 0)
+ return;
+#endif
+
+ /* Print the base ISA, as we already know it's legal. */
+ seq_puts(f, "isa\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.
+ */
+ for (e = ext; *e != '\0'; ++e) {
+ if (isa[0] == e[0]) {
+ seq_write(f, isa, 1);
+ isa++;
+ }
+ }
+
+ /*
+ * 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", orig_isa);
+}
+
+static void print_mmu(struct seq_file *f, const char *mmu_type)
+{
+#if defined(CONFIG_32BIT)
+ if (strcmp(mmu_type, "riscv,sv32") != 0)
+ return;
+#elif defined(CONFIG_64BIT)
+ if (strcmp(mmu_type, "riscv,sv39") != 0 &&
+ strcmp(mmu_type, "riscv,sv48") != 0)
+ return;
+#endif
+
+ seq_printf(f, "mmu\t: %s\n", mmu_type+6);
+}
+
static void *c_start(struct seq_file *m, loff_t *pos)
{
*pos = cpumask_next(*pos - 1, cpu_online_mask);
@@ -83,13 +140,10 @@ static int c_show(struct seq_file *m, void *v)
const char *compat, *isa, *mmu;
seq_printf(m, "hart\t: %lu\n", hart_id);
- if (!of_property_read_string(node, "riscv,isa", &isa)
- && isa[0] == 'r'
- && isa[1] == 'v')
- seq_printf(m, "isa\t: %s\n", isa);
- if (!of_property_read_string(node, "mmu-type", &mmu)
- && !strncmp(mmu, "riscv,", 6))
- seq_printf(m, "mmu\t: %s\n", mmu+6);
+ if (!of_property_read_string(node, "riscv,isa", &isa))
+ print_isa(m, isa);
+ if (!of_property_read_string(node, "mmu-type", &mmu))
+ print_mmu(m, mmu);
if (!of_property_read_string(node, "compatible", &compat)
&& strcmp(compat, "riscv"))
seq_printf(m, "uarch\t: %s\n", compat);