Instead of pushing/popping %RSI to/from the stack every time a function is called from startup_64(), store it in a callee preserved register and grab it from there when its value is actualled needed. Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx> --- arch/x86/kernel/head_64.S | 15 +++------------ 1 file changed, 3 insertions(+), 12 deletions(-) diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S index a5df3e994f04f10f..95b12fdae10e1dc9 100644 --- a/arch/x86/kernel/head_64.S +++ b/arch/x86/kernel/head_64.S @@ -60,6 +60,7 @@ SYM_CODE_START_NOALIGN(startup_64) * compiled to run at we first fixup the physical addresses in our page * tables and then reload them. */ + mov %rsi, %r15 /* Preserve boot_params pointer */ /* Set up the stack for verify_cpu() */ leaq (__end_init_task - PTREGS_SIZE)(%rip), %rsp @@ -73,9 +74,7 @@ SYM_CODE_START_NOALIGN(startup_64) shrq $32, %rdx wrmsr - pushq %rsi call startup_64_setup_env - popq %rsi #ifdef CONFIG_AMD_MEM_ENCRYPT /* @@ -84,10 +83,8 @@ SYM_CODE_START_NOALIGN(startup_64) * which needs to be done before any CPUID instructions are executed in * subsequent code. */ - movq %rsi, %rdi - pushq %rsi + movq %r15, %rdi call sme_enable - popq %rsi #endif /* Now switch to __KERNEL_CS so IRET works reliably */ @@ -109,9 +106,7 @@ SYM_CODE_START_NOALIGN(startup_64) * programmed into CR3. */ leaq _text(%rip), %rdi - pushq %rsi call __startup_64 - popq %rsi /* Form the CR3 value being sure to include the CR3 modifier */ addq $(early_top_pgt - __START_KERNEL_map), %rax @@ -200,10 +195,8 @@ SYM_INNER_LABEL(secondary_startup_64_no_verify, SYM_L_GLOBAL) * %rsi carries pointer to realmode data and is callee-clobbered. Save * and restore it. */ - pushq %rsi movq %rax, %rdi call sev_verify_cbit - popq %rsi /* * Switch to new page-table @@ -294,9 +287,7 @@ SYM_INNER_LABEL(secondary_startup_64_no_verify, SYM_L_GLOBAL) wrmsr /* Setup and Load IDT */ - pushq %rsi call early_setup_idt - popq %rsi /* Check if nx is implemented */ movl $0x80000001, %eax @@ -334,7 +325,7 @@ SYM_INNER_LABEL(secondary_startup_64_no_verify, SYM_L_GLOBAL) /* rsi is pointer to real mode structure with interesting info. pass it to C */ - movq %rsi, %rdi + movq %r15, %rdi .Ljump_to_C_code: /* -- 2.39.2
