[M] Change in coreboot[main]: libpayload/x86: Extend exception handling to x86_64 architecture
Nick Vaccaro has submitted this change. ( https://review.coreboot.org/c/coreboot/+/83036?usp=email )
Change subject: libpayload/x86: Extend exception handling to x86_64 architecture ......................................................................
libpayload/x86: Extend exception handling to x86_64 architecture
Adds 64-bit (x86_64) support to libpayload's exception handler, previously limited to x86_32.
Ensures `exception_init_asm` is called when building with LP_ARCH_X86_64 Kconfig.
BUG=b:336265399 TEST=Successful build and boot of google/rex and google/rex64 on ChromeOS.
Verified correct x86_64 exception handling by triggering "Debug Exception" using firmware-shell as below:
firmware-shell: mm.l -0 Debug Exception Error code: n/a REG_IP: 0x0000000030023e9f REG_FLAGS: 0x0000000000000046 REG_AX: 0x0000000000000009 REG_BX: 0x0000000000000000 REG_CX: 0x0000002000000000 REG_DX: 0x0000000000000001 REG_SP: 0x0000000034072ec0 REG_BP: 0x0000000000000009 REG_SI: 0x0000000000000029 REG_DI: 0x0000000034072eef REG_R8: 0x0000000000000009 REG_R9: 0x0000000000000000 REG_R10: 0x0000000000000000 REG_R11: 0x0000000034072d70 REG_R12: 0x0000000000000004 REG_R13: 0x0000000000000001 REG_R14: 0x0000000034072ee6 REG_R15: 0x0000000000000004 CS: 0x0020 DS: 0x0000 ES: 0x0000 SS: 0x0018 FS: 0x0018 GS: 0x0050 Dumping stack: 0x340730c0: 3003c32e 00000000 ... 00000000 00000000 0x340730a0: 30034bc6 00000000 ... 0000002a 00000000 0x34073080: 34073234 00000000 ... 00002e65 00000000 ... ... 0x34072ee0: 340730ed 30300000 ... 34073000 00000000 0x34072ec0: 34072ed8 00000000 ... 00000000 00000008 Ready for GDB connection.
Change-Id: I8f0aa1da8d179a760e8d49c3764dfd5a69d06887 Signed-off-by: Subrata Banik subratabanik@google.com Reviewed-on: https://review.coreboot.org/c/coreboot/+/83036 Reviewed-by: Kapil Porwal kapilporwal@google.com Reviewed-by: Arthur Heymans arthur@aheymans.xyz Tested-by: build bot (Jenkins) no-reply@coreboot.org --- M payloads/libpayload/arch/x86/exception.c M payloads/libpayload/arch/x86/exception_asm_64.S 2 files changed, 158 insertions(+), 30 deletions(-)
Approvals: Kapil Porwal: Looks good to me, approved build bot (Jenkins): Verified Arthur Heymans: Looks good to me, approved
diff --git a/payloads/libpayload/arch/x86/exception.c b/payloads/libpayload/arch/x86/exception.c index fdab042..9811be3 100644 --- a/payloads/libpayload/arch/x86/exception.c +++ b/payloads/libpayload/arch/x86/exception.c @@ -113,13 +113,15 @@ { int i, j; const int line = 8; - uint32_t *ptr = (uint32_t *)(addr & ~(line * sizeof(*ptr) - 1)); + uint32_t *ptr = (uint32_t *)((uintptr_t)addr & ~(line * sizeof(*ptr) - 1));
printf("Dumping stack:\n"); for (i = bytes / sizeof(*ptr); i >= 0; i -= line) { printf("%p: ", ptr + i); - for (j = i; j < i + line; j++) - printf("%08x ", *(ptr + j)); + for (j = i; j < i + line; j++) { + if ((uintptr_t)(ptr + j) >= addr && (uintptr_t)(ptr + j) < addr + bytes) + printf("%08x ", *(ptr + j)); + } printf("\n"); } } @@ -213,10 +215,6 @@
void exception_init(void) { - /* TODO: Add exception init code for x64, currently only supporting 32-bit code */ - if (CONFIG(LP_ARCH_X86_64)) - return; - exception_stack_end = exception_stack + ARRAY_SIZE(exception_stack); exception_init_asm(); } diff --git a/payloads/libpayload/arch/x86/exception_asm_64.S b/payloads/libpayload/arch/x86/exception_asm_64.S index ee4e9e5..6d91b93 100644 --- a/payloads/libpayload/arch/x86/exception_asm_64.S +++ b/payloads/libpayload/arch/x86/exception_asm_64.S @@ -39,10 +39,10 @@ .quad 0 error_code: .quad 0 -old_rsp: - .quad 0 old_rax: .quad 0 +old_rcx: + .quad 0
.align 16
@@ -55,23 +55,23 @@
.macro stub num exception_stub_\num: - movq $0, error_code - movq $\num, vector - jmp exception_common + movq $0, error_code + movq $\num, vector + jmp exception_common .endm
.macro stub_err num exception_stub_\num: - pop error_code - movq $\num, vector - jmp exception_common + pop error_code + movq $\num, vector + jmp exception_common .endm
.altmacro - .macro user_defined_stubs from, to - stub \from - .if \to-\from - user_defined_stubs %(from+1),\to + .macro user_defined_stubs from, to + stub \from + .if \to-\from + user_defined_stubs %(from+1),\to .endif .endm
@@ -114,9 +114,117 @@ user_defined_stubs 192, 255
exception_common: + /* + * At this point, on x86-64, on the stack there is: + * 0(%rsp) rip + * 8(%rsp) cs + * 16(%rsp) rflags + * 24(%rsp) rsp + * 32(%rsp) ss + * + * This section sets up the exception stack. + * It saves the old stack pointer (rsp) to preserve RIP, CS, RFLAGS and SS. + * Then sets up the new stack pointer to point to the exception stack area. + */ + movq %rax, old_rax + movq %rcx, old_rcx
- /* Return from the exception. */ - iretl + mov %rsp, %rax + movq exception_stack_end, %rsp + /* + * The `exception_state` struct is not 16-byte aligned. + * Push an extra 8 bytes to ensure the stack pointer + * is 16-byte aligned before calling exception_dispatch. + */ + push $0 + + /* + * Push values onto the top of the exception stack to form an + * exception state structure. + */ + push vector + push error_code + + /* push of the gs, fs, es, ds, ss and cs */ + mov %gs, %rcx + movl %ecx, -4(%rsp) /* gs */ + mov %fs, %rcx + movl %ecx, -8(%rsp) /* fs */ + movl $0, -12(%rsp) /* es */ + movl $0, -16(%rsp) /* ds */ + movq 32(%rax), %rcx + movl %ecx, -20(%rsp) /* ss */ + movq 8(%rax), %rcx + movl %ecx, -24(%rsp) /* cs */ + sub $24, %rsp + + push 16(%rax) /* rflags */ + push (%rax) /* rip */ + push %r15 + push %r14 + push %r13 + push %r12 + push %r11 + push %r10 + push %r9 + push %r8 + push 24(%rax) /* rsp */ + push %rbp + push %rdi + push %rsi + push %rdx + push old_rcx /* rcx */ + push %rbx + push old_rax /* rax */ + + /* + * Call the C exception handler. It will find the exception state + * using the exception_state global pointer. Not + * passing parameters means we don't have to worry about what ABI + * is being used. + */ + mov %rsp, exception_state + call exception_dispatch + + /* + * Restore state from the exception state structure, including any + * changes that might have been made. + */ + pop old_rax + pop %rbx + pop old_rcx + pop %rdx + pop %rsi + pop %rdi + pop %rbp + lea exception_stack, %rax + pop 24(%rax) /* rsp */ + pop %r8 + pop %r9 + pop %r10 + pop %r11 + pop %r12 + pop %r13 + pop %r14 + pop %r15 + pop (%rax) /* rip */ + pop 16(%rax) /* rflags */ + + /* pop of the gs, fs, es, ds, ss and cs */ + movl (%rsp), %ecx + movq %rcx, 8(%rax) /* cs */ + movl 4(%rsp), %ecx + movq %rcx, 32(%rax) /* ss */ + movl 16(%rsp), %ecx + mov %rcx, %fs /* fs */ + movl 20(%rsp), %ecx + mov %rcx, %gs /* gs */ + + mov %rax, %rsp + movq old_rax, %rax + movq old_rcx, %rcx + + iretq
/* * We need segment selectors for the IDT, so we need to know where things are @@ -139,18 +247,18 @@
/* selgdt 0x18, flat 4GB data segment */ .word 0xffff, 0x0000 - .byte 0x00, 0x92, 0xcf, 0x00 + .byte 0x00, 0x92, 0xcf, 0x00
/* selgdt 0x20, flat x64 code segment */ - .word 0xffff, 0x0000 - .byte 0x00, 0x9b, 0xaf, 0x00 + .word 0xffff, 0x0000 + .byte 0x00, 0x9b, 0xaf, 0x00 gdt_end:
/* GDT pointer for use with lgdt */ .global gdt_ptr gdt_ptr: - .word gdt_end - gdt - 1 - .quad gdt + .word gdt_end - gdt - 1 + .quad gdt
/* * Record the target and construct the actual entry at init time. This @@ -158,8 +266,11 @@ * for us. */ .macro interrupt_gate target - .quad \target - .quad \target + .word 0 /* patchable */ + .word 0x20 /* Target code segment selector */ + .word 0xee00 /* Present, Type 64-bit Interrupt Gate */ + .word 0 /* patchable */ + .quad \target /* patchable */ .endm
.altmacro @@ -171,7 +282,7 @@ .endm
.align 16 - .global idt + .global idt idt: interrupt_gate exception_stub_0 interrupt_gate exception_stub_1 @@ -216,6 +327,25 @@ .word idt_end - idt - 1 .quad idt
- .global exception_init_asm +.section .text.exception_init_asm +.globl exception_init_asm +.type exception_init_asm, @function + exception_init_asm: + /* Set up IDT entries */ + mov $idt, %rax +1: + movq 8(%rax), %rdi + movw %di, (%rax) /* procedure entry point offset bits 0..15 */ + shr $16, %rdi + movw %di, 6(%rax) /* procedure entry point offset bits 16..31 */ + shr $16, %rdi + movl %edi, 8(%rax) /* procedure entry point offset bits 32..63 */ + movl $0, 12(%rax) /* reserved */ + add $16, %rax + cmp $idt_end, %rax + jne 1b + + /* Load the IDT */ + lidt idt_ptr ret
-
Nick Vaccaro (Code Review)