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ArmPkg: StMM: Use x24 register to store stack address

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Now that the use of 18 registers for FF-A is supported. Registers
from x0-x17 can be used by FF-A to return call results. StMM also uses
registers x19-x23 to store SPMC boot information.

Use the x24 register to store the stack address instead of x12
to avoid it being clobbered by FF-A calls.

Signed-off-by: Mohamed Gamal Morsy <mohamed.morsy@arm.com>
This commit is contained in:
Mohamed Gamal Morsy
2025-05-01 12:41:59 +01:00
committed by mergify[bot]
parent 07425903d3
commit e0852f75d8
1 changed files with 4 additions and 4 deletions
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8
ArmPkg/Library/ArmStandaloneMmCoreEntryPoint/AArch64/ModuleEntryPoint.S
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@@ -81,8 +81,8 @@ ASM_FUNC(SetStackPermissionFfa)
// x1 = stmm_stack top // x1 = stmm_stack top
mov x1, x0 mov x1, x0
// x12 = Compute and save the stack base // x24 = Compute and save the stack base
add x12, x1, x2 add x24, x1, x2
// x2 = Count of pages of stmm_stack // x2 = Count of pages of stmm_stack
lsr x2, x2, #EFI_PAGE_SHIFT lsr x2, x2, #EFI_PAGE_SHIFT
@@ -110,7 +110,7 @@ ASM_FUNC(SetStackPermissionFfa)
cmp x10, #0x00 cmp x10, #0x00
// Set return value as base address of stack. // Set return value as base address of stack.
mov x0, x12 mov x0, x24
b.ne .Lout_set_stack_perm_ffa b.ne .Lout_set_stack_perm_ffa
// If failed, set return value as zero. // If failed, set return value as zero.
mov x0, #0x00 mov x0, #0x00
@@ -119,7 +119,7 @@ ASM_FUNC(SetStackPermissionFfa)
mov x9, xzr mov x9, xzr
mov x10, xzr mov x10, xzr
mov x11, xzr mov x11, xzr
mov x12, xzr mov x24, xzr
ret ret
// //