diff mbox series

[v5,10/21] arm64: cpufeature: Use IDreg override in __read_sysreg_by_encoding()

Message ID 20210125105019.2946057-11-maz@kernel.org (mailing list archive)
State New, archived
Headers show
Series arm64: Early CPU feature override, and applications to VHE, BTI and PAuth | expand

Commit Message

Marc Zyngier Jan. 25, 2021, 10:50 a.m. UTC 
__read_sysreg_by_encoding() is used by a bunch of cpufeature helpers,
which should take the feature override into account. Let's do that.

For a good measure (and because we are likely to need to further
down the line), make this helper available to the rest of the
non-modular kernel.

Code that needs to know the *real* features of a CPU can still
use read_sysreg_s(), and find the bare, ugly truth.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Acked-by: David Brazdil <dbrazdil@google.com>
---
 arch/arm64/include/asm/cpufeature.h |  1 +
 arch/arm64/kernel/cpufeature.c      | 15 +++++++++++++--
 2 files changed, 14 insertions(+), 2 deletions(-)

Comments

Catalin Marinas Jan. 25, 2021, 12:19 p.m. UTC | #1 
On Mon, Jan 25, 2021 at 10:50:08AM +0000, Marc Zyngier wrote:
> __read_sysreg_by_encoding() is used by a bunch of cpufeature helpers,
> which should take the feature override into account. Let's do that.
> 
> For a good measure (and because we are likely to need to further
> down the line), make this helper available to the rest of the
> non-modular kernel.
> 
> Code that needs to know the *real* features of a CPU can still
> use read_sysreg_s(), and find the bare, ugly truth.
> 
> Signed-off-by: Marc Zyngier <maz@kernel.org>
> Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
> Acked-by: David Brazdil <dbrazdil@google.com>

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
diff mbox series

Patch

diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index fe469389068e..4179cfc8ed57 100644
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -606,6 +606,7 @@  void __init setup_cpu_features(void);
 void check_local_cpu_capabilities(void);
 
 u64 read_sanitised_ftr_reg(u32 id);
+u64 __read_sysreg_by_encoding(u32 sys_id);
 
 static inline bool cpu_supports_mixed_endian_el0(void)
 {
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index cb58c7c991ef..4b84a1e1dc51 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -1145,14 +1145,17 @@  u64 read_sanitised_ftr_reg(u32 id)
 EXPORT_SYMBOL_GPL(read_sanitised_ftr_reg);
 
 #define read_sysreg_case(r)	\
-	case r:		return read_sysreg_s(r)
+	case r:		val = read_sysreg_s(r); break;
 
 /*
  * __read_sysreg_by_encoding() - Used by a STARTING cpu before cpuinfo is populated.
  * Read the system register on the current CPU
  */
-static u64 __read_sysreg_by_encoding(u32 sys_id)
+u64 __read_sysreg_by_encoding(u32 sys_id)
 {
+	struct arm64_ftr_reg *regp;
+	u64 val;
+
 	switch (sys_id) {
 	read_sysreg_case(SYS_ID_PFR0_EL1);
 	read_sysreg_case(SYS_ID_PFR1_EL1);
@@ -1195,6 +1198,14 @@  static u64 __read_sysreg_by_encoding(u32 sys_id)
 		BUG();
 		return 0;
 	}
+
+	regp  = get_arm64_ftr_reg(sys_id);
+	if (regp) {
+		val &= ~regp->override->mask;
+		val |= (regp->override->val & regp->override->mask);
+	}
+
+	return val;
 }
 
 #include <linux/irqchip/arm-gic-v3.h>