arm64: fix KASAN_INLINE

Since commit:

  a004393f45d9a55e ("arm64: idreg-override: use early FDT mapping in ID map")

Kernels built with KASAN_INLINE=y die early in boot before producing any
console output. This is because the accesses made to the FDT (e.g. in
generic string processing functions) are instrumented with KASAN, and
with KASAN_INLINE=y any access to an address in TTBR0 results in a bogus
shadow VA, resulting in a data abort.

This patch fixes this by reverting commits:

  7559d9f97581654f ("arm64: setup: drop early FDT pointer helpers")
  bd0c3fa21878b6d0 ("arm64: idreg-override: use early FDT mapping in ID map")

... and using the TTBR1 fixmap mapping of the FDT.

Note that due to a later commit:

  b65e411d6cc2f12a ("arm64: Save state of HCR_EL2.E2H before switch to EL1")

... which altered the prototype of init_feature_override() (and
invocation from head.S), commit bd0c3fa21878b6d0 does not revert
cleanly, and I've fixed that up manually.

Fixes: a004393f45d9 ("arm64: idreg-override: use early FDT mapping in ID map")
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Will Deacon <will@kernel.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20220713140949.45440-1-mark.rutland@arm.com
Signed-off-by: Will Deacon <will@kernel.org>

diff --git a/arch/arm64/include/asm/setup.h b/arch/arm64/include/asm/setup.h
index 5f147a418281ec95d00dce32525b40f502fc200e..6437df661700920473aa9ccb1f217985436f856c 100644 (file)
--- a/arch/arm64/include/asm/setup.h
+++ b/arch/arm64/include/asm/setup.h
@@ -5,6 +5,9 @@
 
 #include <uapi/asm/setup.h>
 
+void *get_early_fdt_ptr(void);
+void early_fdt_map(u64 dt_phys);
+
 /*
  * These two variables are used in the head.S file.
  */

diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
index 29d641290293bfabff48992092815c4410661f0b..cefe6a73ee546c26e8971bce4abf4b01f6e5f96d 100644 (file)
--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S
@@ -456,8 +456,9 @@ SYM_FUNC_START_LOCAL(__primary_switched)
 #if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
        bl      kasan_early_init
 #endif
-       mov     x0, x22                         // pass FDT address in x0
-       mov     x1, x20                         // pass the full boot status
+       mov     x0, x21                         // pass FDT address in x0
+       bl      early_fdt_map                   // Try mapping the FDT early
+       mov     x0, x20                         // pass the full boot status
        bl      init_feature_override           // Parse cpu feature overrides
        mov     x0, x20
        bl      finalise_el2                    // Prefer VHE if possible

diff --git a/arch/arm64/kernel/idreg-override.c b/arch/arm64/kernel/idreg-override.c
index aa2a53d0d4172e3259e4d1f74aaaf4a296696541..7206fd0ed9eb47d139a5eafeee54d5ab1ccbe0ba 100644 (file)
--- a/arch/arm64/kernel/idreg-override.c
+++ b/arch/arm64/kernel/idreg-override.c
@@ -262,11 +262,16 @@ static __init void __parse_cmdline(const char *cmdline, bool parse_aliases)
        } while (1);
 }
 
-static __init const u8 *get_bootargs_cmdline(const void *fdt)
+static __init const u8 *get_bootargs_cmdline(void)
 {
        const u8 *prop;
+       void *fdt;
        int node;
 
+       fdt = get_early_fdt_ptr();
+       if (!fdt)
+               return NULL;
+
        node = fdt_path_offset(fdt, "/chosen");
        if (node < 0)
                return NULL;
@@ -278,9 +283,9 @@ static __init const u8 *get_bootargs_cmdline(const void *fdt)
        return strlen(prop) ? prop : NULL;
 }
 
-static __init void parse_cmdline(const void *fdt)
+static __init void parse_cmdline(void)
 {
-       const u8 *prop = get_bootargs_cmdline(fdt);
+       const u8 *prop = get_bootargs_cmdline();
 
        if (IS_ENABLED(CONFIG_CMDLINE_FORCE) || !prop)
                __parse_cmdline(CONFIG_CMDLINE, true);
@@ -290,9 +295,9 @@ static __init void parse_cmdline(const void *fdt)
 }
 
 /* Keep checkers quiet */
-void init_feature_override(const void *fdt, u64 boot_status);
+void init_feature_override(u64 boot_status);
 
-asmlinkage void __init init_feature_override(const void *fdt, u64 boot_status)
+asmlinkage void __init init_feature_override(u64 boot_status)
 {
        int i;
 
@@ -305,7 +310,7 @@ asmlinkage void __init init_feature_override(const void *fdt, u64 boot_status)
 
        __boot_status = boot_status;
 
-       parse_cmdline(fdt);
+       parse_cmdline();
 
        for (i = 0; i < ARRAY_SIZE(regs); i++) {
                if (regs[i]->override)

diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
index d0e6c7a291da8ab8b956f41b0de0c9198461c494..fea3223704b6339a0381ddee334168ec5d83201b 100644 (file)
--- a/arch/arm64/kernel/setup.c
+++ b/arch/arm64/kernel/setup.c
@@ -163,6 +163,21 @@ static void __init smp_build_mpidr_hash(void)
                pr_warn("Large number of MPIDR hash buckets detected\n");
 }
 
+static void *early_fdt_ptr __initdata;
+
+void __init *get_early_fdt_ptr(void)
+{
+       return early_fdt_ptr;
+}
+
+asmlinkage void __init early_fdt_map(u64 dt_phys)
+{
+       int fdt_size;
+
+       early_fixmap_init();
+       early_fdt_ptr = fixmap_remap_fdt(dt_phys, &fdt_size, PAGE_KERNEL);
+}
+
 static void __init setup_machine_fdt(phys_addr_t dt_phys)
 {
        int size;