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Message-Id: <20230329052926.69632-5-alexghiti@rivosinc.com>
Date: Wed, 29 Mar 2023 07:29:26 +0200
From: Alexandre Ghiti <alexghiti@...osinc.com>
To: Paul Walmsley <paul.walmsley@...ive.com>,
Palmer Dabbelt <palmer@...belt.com>,
Albert Ou <aou@...s.berkeley.edu>,
Ard Biesheuvel <ardb@...nel.org>,
linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
linux-efi@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Cc: Alexandre Ghiti <alexghiti@...osinc.com>
Subject: [PATCH v2 4/4] riscv: libstub: Implement KASLR by using generic functions
We can now use arm64 functions to handle the move of the kernel physical
mapping: if KASLR is enabled, we will try to get a random seed from the
firmware, if not possible, the kernel will be moved to a location that
suits its alignment constraints.
Signed-off-by: Alexandre Ghiti <alexghiti@...osinc.com>
---
arch/riscv/kernel/image-vars.h | 1 +
drivers/firmware/efi/libstub/arm64.c | 5 ++++
.../firmware/efi/libstub/efi-stub-helper.c | 2 +-
drivers/firmware/efi/libstub/efistub.h | 2 ++
drivers/firmware/efi/libstub/riscv-stub.c | 28 +++++++------------
drivers/firmware/efi/libstub/riscv.c | 5 ++++
6 files changed, 24 insertions(+), 19 deletions(-)
diff --git a/arch/riscv/kernel/image-vars.h b/arch/riscv/kernel/image-vars.h
index 15616155008c..ea1a10355ce9 100644
--- a/arch/riscv/kernel/image-vars.h
+++ b/arch/riscv/kernel/image-vars.h
@@ -27,6 +27,7 @@ __efistub__start = _start;
__efistub__start_kernel = _start_kernel;
__efistub__end = _end;
__efistub__edata = _edata;
+__efistub___init_text_end = __init_text_end;
__efistub_screen_info = screen_info;
#endif
diff --git a/drivers/firmware/efi/libstub/arm64.c b/drivers/firmware/efi/libstub/arm64.c
index 399770266372..48bc7428d6df 100644
--- a/drivers/firmware/efi/libstub/arm64.c
+++ b/drivers/firmware/efi/libstub/arm64.c
@@ -108,3 +108,8 @@ void __noreturn efi_enter_kernel(unsigned long entrypoint,
enter_kernel = (void *)entrypoint + primary_entry_offset();
enter_kernel(fdt_addr, 0, 0, 0);
}
+
+void efi_icache_sync(unsigned long start, unsigned long end)
+{
+ caches_clean_inval_pou(start, end);
+}
diff --git a/drivers/firmware/efi/libstub/efi-stub-helper.c b/drivers/firmware/efi/libstub/efi-stub-helper.c
index 40ac2625949c..63c7275d42e7 100644
--- a/drivers/firmware/efi/libstub/efi-stub-helper.c
+++ b/drivers/firmware/efi/libstub/efi-stub-helper.c
@@ -865,7 +865,7 @@ efi_status_t efi_kaslr_relocate_kernel(unsigned long *image_addr,
memcpy((void *)*reserve_addr, (void *)*image_addr, kernel_size);
*image_addr = *reserve_addr;
- caches_clean_inval_pou(*image_addr, *image_addr + kernel_codesize);
+ efi_icache_sync(*image_addr, *image_addr + kernel_codesize);
return status;
}
diff --git a/drivers/firmware/efi/libstub/efistub.h b/drivers/firmware/efi/libstub/efistub.h
index 64273371ce96..9ce114e04b23 100644
--- a/drivers/firmware/efi/libstub/efistub.h
+++ b/drivers/firmware/efi/libstub/efistub.h
@@ -1107,4 +1107,6 @@ efi_status_t efi_kaslr_relocate_kernel(unsigned long *image_addr,
u32 phys_seed);
u32 efi_kaslr_get_phys_seed(efi_handle_t image_handle);
+void efi_icache_sync(unsigned long start, unsigned long end);
+
#endif
diff --git a/drivers/firmware/efi/libstub/riscv-stub.c b/drivers/firmware/efi/libstub/riscv-stub.c
index 145c9f0ba217..7af07b33a993 100644
--- a/drivers/firmware/efi/libstub/riscv-stub.c
+++ b/drivers/firmware/efi/libstub/riscv-stub.c
@@ -30,32 +30,24 @@ efi_status_t handle_kernel_image(unsigned long *image_addr,
efi_loaded_image_t *image,
efi_handle_t image_handle)
{
- unsigned long kernel_size = 0;
- unsigned long preferred_addr;
+ unsigned long kernel_size, kernel_codesize, kernel_memsize;
efi_status_t status;
kernel_size = _edata - _start;
+ kernel_codesize = __init_text_end - _start;
+ kernel_memsize = kernel_size + (_end - _edata);
*image_addr = (unsigned long)_start;
- *image_size = kernel_size + (_end - _edata);
-
- /*
- * RISC-V kernel maps PAGE_OFFSET virtual address to the same physical
- * address where kernel is booted. That's why kernel should boot from
- * as low as possible to avoid wastage of memory. Currently, dram_base
- * is occupied by the firmware. So the preferred address for kernel to
- * boot is next aligned address. If preferred address is not available,
- * relocate_kernel will fall back to efi_low_alloc_above to allocate
- * lowest possible memory region as long as the address and size meets
- * the alignment constraints.
- */
- preferred_addr = EFI_KIMG_PREFERRED_ADDRESS;
- status = efi_relocate_kernel(image_addr, kernel_size, *image_size,
- preferred_addr, efi_get_kimg_min_align(),
- 0x0);
+ *image_size = kernel_memsize;
+ *reserve_size = *image_size;
+ status = efi_kaslr_relocate_kernel(image_addr,
+ reserve_addr, reserve_size,
+ kernel_size, kernel_codesize, kernel_memsize,
+ efi_kaslr_get_phys_seed(image_handle));
if (status != EFI_SUCCESS) {
efi_err("Failed to relocate kernel\n");
*image_size = 0;
}
+
return status;
}
diff --git a/drivers/firmware/efi/libstub/riscv.c b/drivers/firmware/efi/libstub/riscv.c
index 8022b104c3e6..365f891e598f 100644
--- a/drivers/firmware/efi/libstub/riscv.c
+++ b/drivers/firmware/efi/libstub/riscv.c
@@ -96,3 +96,8 @@ void __noreturn efi_enter_kernel(unsigned long entrypoint, unsigned long fdt,
csr_write(CSR_SATP, 0);
jump_kernel(hartid, fdt);
}
+
+void efi_icache_sync(unsigned long start, unsigned long end)
+{
+ asm volatile ("fence.i" ::: "memory");
+}
--
2.37.2
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