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authorPatrick Rudolph <patrick.rudolph@9elements.com>2021-12-03 17:32:07 +0100
committerLean Sheng Tan <sheng.tan@9elements.com>2024-01-11 10:55:30 +0000
commit1c4c7ad1e5af3a9d9bdd061f5bb4780a4292021f (patch)
treeee373ebd36cef2f72f35c13dfadc88229bc30def /src/arch
parent2fb1928b3c1bd74b1c3d412fb119629197868fa4 (diff)
arch/x86/c_start.S: Add proper x86_64 code
Don't truncate upper bits in assembly code and thus allow loading of ramstage above 4GiB. Tested on qemu with cbmem_top set to TOUUD. Change-Id: Ifc9b45f69d0b7534b2faacaad0d099cef2667478 Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com> Co-authored-by: Benjamin Doron <benjamin.doron@9elements.com> Reviewed-on: https://review.coreboot.org/c/coreboot/+/59874 Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Diffstat (limited to 'src/arch')
-rw-r--r--src/arch/x86/c_start.S24
1 files changed, 24 insertions, 0 deletions
diff --git a/src/arch/x86/c_start.S b/src/arch/x86/c_start.S
index 02ddf75d12..6bea8db10d 100644
--- a/src/arch/x86/c_start.S
+++ b/src/arch/x86/c_start.S
@@ -59,6 +59,24 @@ _start:
leal _stack, %edi
#endif
+#if ENV_X86_64
+ /** poison the stack. Code should not count on the
+ * stack being full of zeros. This stack poisoning
+ * recently uncovered a bug in the broadcast SIPI
+ * code.
+ */
+ movabs $_estack, %rcx
+ sub %rdi, %rcx
+ shr $3, %rcx /* it is 64 bit aligned, right? */
+ movq $0xDEADBEEFDEADBEEF, %rax
+ rep
+ stosq
+
+ /* Set new stack with enforced alignment. */
+ movabs $_estack, %rsp
+ movq $(0xfffffffffffffff0), %rax
+ and %rax, %rsp
+#else
/** poison the stack. Code should not count on the
* stack being full of zeros. This stack poisoning
* recently uncovered a bug in the broadcast SIPI
@@ -74,6 +92,7 @@ _start:
/* Set new stack with enforced alignment. */
movl $_estack, %esp
andl $(0xfffffff0), %esp
+#endif
/*
* Now we are finished. Memory is up, data is copied and
@@ -82,7 +101,12 @@ _start:
*/
post_code(POSTCODE_PRE_HARDWAREMAIN) /* post 6e */
+#if ENV_X86_64
+ movq $0xFFFFFFFFFFFFFFF0, %rax
+ and %rax, %rsp
+#else
andl $0xFFFFFFF0, %esp
+#endif
#if CONFIG(ASAN_IN_RAMSTAGE)
call asan_init