Commit 3577dd37 authored by Anshuman Khandual's avatar Anshuman Khandual Committed by Will Deacon
Browse files

arm64/cpufeature: Add get_arm64_ftr_reg_nowarn() 



There is no way to proceed when requested register could not be searched in
arm64_ftr_reg[]. Requesting for a non present register would be an error as
well. Hence lets just WARN_ON() when search fails in get_arm64_ftr_reg()
rather than checking for return value and doing a BUG_ON() instead in some
individual callers. But there are also caller instances that dont error out
when register search fails. Add a new helper get_arm64_ftr_reg_nowarn() for
such cases.

Signed-off-by: default avatarAnshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Link: https://lore.kernel.org/r/1590573876-19120-1-git-send-email-anshuman.khandual@arm.com


Signed-off-by: default avatarWill Deacon <will@kernel.org>
parent 858b8a80

arch/arm64/kernel/cpufeature.c

+34 −10
Original line number Diff line number Diff line
@@ -595,8 +595,8 @@ static int search_cmp_ftr_reg(const void *id, const void *regp) 
}



/*

 * get_arm64_ftr_reg - Lookup a feature register entry using its

 * sys_reg() encoding. With the array arm64_ftr_regs sorted in the

 * get_arm64_ftr_reg_nowarn - Looks up a feature register entry using

 * its sys_reg() encoding. With the array arm64_ftr_regs sorted in the

 * ascending order of sys_id, we use binary search to find a matching

 * entry.

 *
@@ -604,7 +604,7 @@ static int search_cmp_ftr_reg(const void *id, const void *regp) 
 *         - NULL on failure. It is upto the caller to decide

 *	     the impact of a failure.

 */

static struct arm64_ftr_reg *get_arm64_ftr_reg(u32 sys_id)

static struct arm64_ftr_reg *get_arm64_ftr_reg_nowarn(u32 sys_id)

{

	const struct __ftr_reg_entry *ret;
@@ -618,6 +618,27 @@ static struct arm64_ftr_reg *get_arm64_ftr_reg(u32 sys_id) 
	return NULL;

}



/*

 * get_arm64_ftr_reg - Looks up a feature register entry using

 * its sys_reg() encoding. This calls get_arm64_ftr_reg_nowarn().

 *

 * returns - Upon success,  matching ftr_reg entry for id.

 *         - NULL on failure but with an WARN_ON().

 */

static struct arm64_ftr_reg *get_arm64_ftr_reg(u32 sys_id)

{

	struct arm64_ftr_reg *reg;



	reg = get_arm64_ftr_reg_nowarn(sys_id);



	/*

	 * Requesting a non-existent register search is an error. Warn

	 * and let the caller handle it.

	 */

	WARN_ON(!reg);

	return reg;

}



static u64 arm64_ftr_set_value(const struct arm64_ftr_bits *ftrp, s64 reg,

			       s64 ftr_val)

{
@@ -679,7 +700,8 @@ static void __init init_cpu_ftr_reg(u32 sys_reg, u64 new) 
	const struct arm64_ftr_bits *ftrp;

	struct arm64_ftr_reg *reg = get_arm64_ftr_reg(sys_reg);



	BUG_ON(!reg);

	if (!reg)

		return;



	for (ftrp = reg->ftr_bits; ftrp->width; ftrp++) {

		u64 ftr_mask = arm64_ftr_mask(ftrp);
@@ -813,7 +835,9 @@ static int check_update_ftr_reg(u32 sys_id, int cpu, u64 val, u64 boot) 
{

	struct arm64_ftr_reg *regp = get_arm64_ftr_reg(sys_id);



	BUG_ON(!regp);

	if (!regp)

		return 0;



	update_cpu_ftr_reg(regp, val);

	if ((boot & regp->strict_mask) == (val & regp->strict_mask))

		return 0;
@@ -827,7 +851,7 @@ static void relax_cpu_ftr_reg(u32 sys_id, int field) 
	const struct arm64_ftr_bits *ftrp;

	struct arm64_ftr_reg *regp = get_arm64_ftr_reg(sys_id);



	if (WARN_ON(!regp))

	if (!regp)

		return;



	for (ftrp = regp->ftr_bits; ftrp->width; ftrp++) {
@@ -1020,8 +1044,8 @@ u64 read_sanitised_ftr_reg(u32 id) 
{

	struct arm64_ftr_reg *regp = get_arm64_ftr_reg(id);



	/* We shouldn't get a request for an unsupported register */

	BUG_ON(!regp);

	if (!regp)

		return 0;

	return regp->sys_val;

}
@@ -2626,7 +2650,7 @@ static int emulate_sys_reg(u32 id, u64 *valp) 
	if (sys_reg_CRm(id) == 0)

		return emulate_id_reg(id, valp);



	regp = get_arm64_ftr_reg(id);

	regp = get_arm64_ftr_reg_nowarn(id);

	if (regp)

		*valp = arm64_ftr_reg_user_value(regp);

	else

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