[PATCH] iommu/arm-smmu-v3: Fix L1 stream table index calculation for AmpereOne

[Yang Shi]

The commit ce410410f1a7 ("iommu/arm-smmu-v3: Add arm_smmu_strtab_l1/2_idx()")
calculated the last index of L1 stream table by 1 << smmu->sid_bits. 1
is 32 bit value.
However AmpereOne has 32-bit stream id size.  This resulted in
ouf-of-bound shift.  The disassembly of shift is:

    ldr     w2, [x19, 828]  //, smmu_7(D)->sid_bits
    mov     w20, 1
    lsl     w20, w20, w2

According to ARM spec, if the registers are 32 bit, the instruction actually
does:
    dest = src << (shift % 32)

So it actually shifted by zero bit.

This caused v6.12-rc1 failed to boot on AmpereOne and UBSAN also
reported:

UBSAN: shift-out-of-bounds in drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c:3628:29
shift exponent 32 is too large for 32-bit type 'int'
CPU: 70 UID: 0 PID: 1 Comm: swapper/0 Not tainted 6.12.0-rc1 #4
Hardware name: ZOLLNER SUNMOONLAKE/SunMoon Lake, BIOS 00.00. 2024-08-28 18:42:45 08/28/2024
Call trace:
 dump_backtrace+0xdc/0x140
 show_stack+0x20/0x40
 dump_stack_lvl+0x60/0x80
 dump_stack+0x18/0x28
 ubsan_epilogue+0x10/0x48
 __ubsan_handle_shift_out_of_bounds+0xd8/0x1a0
 arm_smmu_init_structures+0x374/0x3c8
 arm_smmu_device_probe+0x208/0x600
 platform_probe+0x70/0xe8
 really_probe+0xc8/0x3a0
 __driver_probe_device+0x84/0x160
 driver_probe_device+0x44/0x130
 __driver_attach+0xcc/0x208
 bus_for_each_dev+0x84/0x100
 driver_attach+0x2c/0x40
 bus_add_driver+0x158/0x290
 driver_register+0x70/0x138
 __platform_driver_register+0x2c/0x40
 arm_smmu_driver_init+0x28/0x40
 do_one_initcall+0x60/0x318
 do_initcalls+0x198/0x1e0
 kernel_init_freeable+0x18c/0x1e8
 kernel_init+0x28/0x160
 ret_from_fork+0x10/0x20

Using 64 bit immediate when doing shift can solve the problem.  The
disssembly after the fix looks like:
    ldr     w20, [x19, 828] //, smmu_7(D)->sid_bits
    mov     x0, 1
    lsl     x0, x0, x20

Signed-off-by: Yang Shi <yang at os.amperecomputing.com>
---
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
index 737c5b882355..01a2faee04bc 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -3625,7 +3625,7 @@ static int arm_smmu_init_strtab_2lvl(struct arm_smmu_device *smmu)
 	u32 l1size;
 	struct arm_smmu_strtab_cfg *cfg = &smmu->strtab_cfg;
 	unsigned int last_sid_idx =
-		arm_smmu_strtab_l1_idx((1 << smmu->sid_bits) - 1);
+		arm_smmu_strtab_l1_idx((1UL << smmu->sid_bits) - 1);
 
 	/* Calculate the L1 size, capped to the SIDSIZE. */
 	cfg->l2.num_l1_ents = min(last_sid_idx + 1, STRTAB_MAX_L1_ENTRIES);
-- 
2.41.0