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| author | Ard Biesheuvel <ard.biesheuvel@linaro.org> | 2016-08-31 13:05:16 +0200 |
|---|---|---|
| committer | Will Deacon <will.deacon@arm.com> | 2016-09-02 12:47:51 +0200 |
| commit | 60699ba18b69ff210ed0304bc23f6c9d11d27a72 (patch) | |
| tree | dc618b2522ad8382207796cc43f772ebf4c250d4 /arch/arm64/kernel/head.S | |
| parent | arm64: kernel: drop use of x24 from primary boot path (diff) | |
| download | linux-60699ba18b69ff210ed0304bc23f6c9d11d27a72.tar.xz linux-60699ba18b69ff210ed0304bc23f6c9d11d27a72.zip | |
arm64: head.S: use ordinary stack frame for __primary_switched()
Instead of stashing the value of the link register in x28 before setting
up the stack and calling into C code, create an ordinary PCS compatible
stack frame so that we can push the return address onto the stack.
Since exception handlers require a stack as well, assign the stack pointer
register before installing the vector table.
Note that this accounts for the difference between THREAD_START_SP and
THREAD_SIZE, given that the stack pointer is always decremented before
calling into any C code.
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'arch/arm64/kernel/head.S')
| -rw-r--r-- | arch/arm64/kernel/head.S | 18 |
1 files changed, 9 insertions, 9 deletions
diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S index 4dee51045e79..29a734ee0770 100644 --- a/arch/arm64/kernel/head.S +++ b/arch/arm64/kernel/head.S @@ -415,13 +415,18 @@ ENDPROC(__create_page_tables) * * x0 = __PHYS_OFFSET */ - .set initial_sp, init_thread_union + THREAD_START_SP __primary_switched: - mov x28, lr // preserve LR + adrp x4, init_thread_union + add sp, x4, #THREAD_SIZE + msr sp_el0, x4 // Save thread_info + adr_l x8, vectors // load VBAR_EL1 with virtual msr vbar_el1, x8 // vector table address isb + stp xzr, x30, [sp, #-16]! + mov x29, sp + str_l x21, __fdt_pointer, x5 // Save FDT pointer ldr_l x4, kimage_vaddr // Save the offset between @@ -436,11 +441,6 @@ __primary_switched: bl __pi_memset dsb ishst // Make zero page visible to PTW - adr_l sp, initial_sp, x4 - mov x4, sp - and x4, x4, #~(THREAD_SIZE - 1) - msr sp_el0, x4 // Save thread_info - mov x29, #0 #ifdef CONFIG_KASAN bl kasan_early_init #endif @@ -452,8 +452,8 @@ __primary_switched: bl kaslr_early_init // parse FDT for KASLR options cbz x0, 0f // KASLR disabled? just proceed orr x23, x23, x0 // record KASLR offset - ret x28 // we must enable KASLR, return - // to __primary_switch() + ldp x29, x30, [sp], #16 // we must enable KASLR, return + ret // to __primary_switch() 0: #endif b start_kernel |