[PATCH v2 1/4] ARM: stm32: Fix ECDSA authentication with Dcache enabled

[Marek Vasut]

In case Dcache is enabled while the ECDSA authentication function is
called via BootROM ROM API, the CRYP DMA might pick stale version of
data from DRAM. Disable Dcache around the BootROM call to avoid this
issue.

Signed-off-by: Marek Vasut <marex at denx.de>
---
Cc: Alexandru Gagniuc <mr.nuke.me at gmail.com>
Cc: Patrice Chotard <patrice.chotard at foss.st.com>
Cc: Patrick Delaunay <patrick.delaunay at foss.st.com>
---
V2: - Initialize reenable_dcache variable
---
 arch/arm/mach-stm32mp/ecdsa_romapi.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/arch/arm/mach-stm32mp/ecdsa_romapi.c b/arch/arm/mach-stm32mp/ecdsa_romapi.c
index a2f63ff879f..082178ce83f 100644
--- a/arch/arm/mach-stm32mp/ecdsa_romapi.c
+++ b/arch/arm/mach-stm32mp/ecdsa_romapi.c
@@ -63,6 +63,7 @@ static int romapi_ecdsa_verify(struct udevice *dev,
 			       const void *hash, size_t hash_len,
 			       const void *signature, size_t sig_len)
 {
+	bool reenable_dcache = false;
 	struct ecdsa_rom_api rom;
 	uint8_t raw_key[64];
 	uint32_t rom_ret;
@@ -81,8 +82,21 @@ static int romapi_ecdsa_verify(struct udevice *dev,
 	memcpy(raw_key + 32, pubkey->y, 32);
 
 	stm32mp_rom_get_ecdsa_functions(&rom);
+
+	/*
+	 * Disable D-cache before calling into BootROM, else CRYP DMA
+	 * may fail to pick up the correct data.
+	 */
+	if (dcache_status()) {
+		dcache_disable();
+		reenable_dcache = true;
+	}
+
 	rom_ret = rom.ecdsa_verify_signature(hash, raw_key, signature, algo);
 
+	if (reenable_dcache)
+		dcache_enable();
+
 	return rom_ret == ROM_API_SUCCESS ? 0 : -EPERM;
 }
 
-- 
2.35.1