7.3-stable review patch. If anyone has any objections, please let me know. ------------------ From: Yo'av Moshe [ Upstream commit 242757d109bd5c9b8fb7194fb4d44625be0b859a ] The suspend code that runs from OCRAM is copied there with fncpy(), which does not copy the kCFI type hash preceding the function. With CONFIG_CFI=y the indirect call through imx6_suspend_in_ocram_fn therefore panics. Keep the call covered by CFI instead of exempting it: - Add SYM_TYPED_FUNC_START_ALIGNED(), a variant of SYM_TYPED_FUNC_START() that aligns the function entry rather than the type hash preceding it, and use it to declare imx6_suspend(): fncpy() requires the entry point of the function it copies to be 8-byte aligned. The macro lives in arch/arm/include/asm/linkage.h since the requirement comes from arm's fncpy(). - Add a cfi_type member at the end of struct imx6_cpu_pm_info, which directly precedes the OCRAM copy of the function. It fits in the struct's tail padding, so no sizes or offsets change. Fill it using cfi_get_func_hash(), putting the hash where the caller's CFI check expects it: four bytes before the function entry. Also mark ccm_base, suspend_ocram_base and imx6_suspend_in_ocram_fn as __ro_after_init: they are only written during __init, and the function pointer in particular should not be writable afterwards. Suggested-by: Nick Desaulniers Cc: stable@vger.kernel.org Signed-off-by: Yo'av Moshe Reviewed-by: Nick Desaulniers Reviewed-by: Sami Tolvanen Signed-off-by: Frank Li Signed-off-by: Sasha Levin --- arch/arm/include/asm/linkage.h | 29 +++++++++++++++++++++++++++++ arch/arm/mach-imx/pm-imx6.c | 26 +++++++++++++++++++++++--- arch/arm/mach-imx/suspend-imx6.S | 6 ++++-- 3 files changed, 56 insertions(+), 5 deletions(-) diff --git a/arch/arm/include/asm/linkage.h b/arch/arm/include/asm/linkage.h index c4670694ada79..bba992f5d7a80 100644 --- a/arch/arm/include/asm/linkage.h +++ b/arch/arm/include/asm/linkage.h @@ -9,4 +9,33 @@ .type name, %function; \ END(name) +#ifdef __ASSEMBLY__ + +/* + * Variants of SYM_TYPED_START/SYM_TYPED_FUNC_START that align the + * function entry itself instead of the kCFI type hash preceding it, + * for functions whose entry point must meet an alignment requirement, + * such as the 8-byte alignment fncpy() demands of its source. + */ +#ifdef CONFIG_CFI + +#define SYM_TYPED_START_ALIGNED(name, linkage, align) \ + linkage(name) ASM_NL \ + .balign align ASM_NL \ + .fill (align) - 4, 1, 0 ASM_NL \ + __CFI_TYPE(name) ASM_NL \ + name: + +#else /* CONFIG_CFI */ + +#define SYM_TYPED_START_ALIGNED(name, linkage, align) \ + SYM_START(name, linkage, .balign align) + +#endif /* CONFIG_CFI */ + +#define SYM_TYPED_FUNC_START_ALIGNED(name, align) \ + SYM_TYPED_START_ALIGNED(name, SYM_L_GLOBAL, align) + +#endif /* __ASSEMBLY__ */ + #endif diff --git a/arch/arm/mach-imx/pm-imx6.c b/arch/arm/mach-imx/pm-imx6.c index a671ca498f887..3c73e2cdb8ceb 100644 --- a/arch/arm/mach-imx/pm-imx6.c +++ b/arch/arm/mach-imx/pm-imx6.c @@ -4,6 +4,8 @@ * Copyright 2011 Linaro Ltd. */ +#include +#include #include #include #include @@ -18,6 +20,7 @@ #include #include #include +#include #include #include #include @@ -61,9 +64,9 @@ #define MX6Q_SUSPEND_OCRAM_SIZE 0x1000 #define MX6_MAX_MMDC_IO_NUM 33 -static void __iomem *ccm_base; -static void __iomem *suspend_ocram_base; -static void (*imx6_suspend_in_ocram_fn)(void __iomem *ocram_vbase); +static void __iomem *ccm_base __ro_after_init; +static void __iomem *suspend_ocram_base __ro_after_init; +static void (*imx6_suspend_in_ocram_fn)(void __iomem *ocram_vbase) __ro_after_init; /* * suspend ocram space layout: @@ -229,8 +232,18 @@ struct imx6_cpu_pm_info { struct imx6_pm_base l2_base; u32 mmdc_io_num; /* Number of MMDC IOs which need saved/restored. */ u32 mmdc_io_val[MX6_MAX_MMDC_IO_NUM][2]; /* To save offset and value */ + u32 cfi_type; /* kCFI type hash of imx6_suspend() */ } __aligned(8); +/* + * The ocram copy of imx6_suspend() starts right after struct imx6_cpu_pm_info, + * and the CFI check on the indirect call reads the kCFI type hash from the + * four bytes preceding the function entry, so cfi_type must occupy the last + * four bytes of the struct, i.e. fit into its tail padding. + */ +static_assert(offsetofend(struct imx6_cpu_pm_info, cfi_type) == + sizeof(struct imx6_cpu_pm_info)); + void imx6_set_int_mem_clk_lpm(bool enable) { u32 val = readl_relaxed(ccm_base + CGPR); @@ -568,6 +581,13 @@ static int __init imx6q_suspend_init(const struct imx6_pm_socdata *socdata) mmdc_offset_array[i]); } + /* + * Mask out the Thumb bit, as cfi_get_func_hash() expects the + * function's actual start address. Returns 0 if CONFIG_CFI=n. + */ + pm_info->cfi_type = + cfi_get_func_hash((void *)((uintptr_t)&imx6_suspend & ~1UL)); + imx6_suspend_in_ocram_fn = fncpy( suspend_ocram_base + sizeof(*pm_info), &imx6_suspend, diff --git a/arch/arm/mach-imx/suspend-imx6.S b/arch/arm/mach-imx/suspend-imx6.S index 63ccc2d0e920a..95d5f723ea0ed 100644 --- a/arch/arm/mach-imx/suspend-imx6.S +++ b/arch/arm/mach-imx/suspend-imx6.S @@ -3,6 +3,7 @@ * Copyright 2014 Freescale Semiconductor, Inc. */ +#include #include #include #include @@ -148,7 +149,8 @@ .endm -ENTRY(imx6_suspend) +/* fncpy() requires an 8-byte-aligned entry; see arch/arm/include/asm/fncpy.h */ +SYM_TYPED_FUNC_START_ALIGNED(imx6_suspend, 8) ldr r1, [r0, #PM_INFO_PBASE_OFFSET] ldr r2, [r0, #PM_INFO_RESUME_ADDR_OFFSET] ldr r3, [r0, #PM_INFO_DDR_TYPE_OFFSET] @@ -329,4 +331,4 @@ resume: resume_mmdc ret lr -ENDPROC(imx6_suspend) +SYM_FUNC_END(imx6_suspend) -- 2.53.0