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    Subject[TRIVIAL PATCH 01/26] vsprintf: Add extension %pSR - print_symbol replacement
    Date
    print_symbol takes a long and converts it to a function
    name and offset. %pS does something similar, but doesn't
    translate the address via __builtin_extract_return_addr.
    %pSR does the translation.

    This will enable replacing multiple calls like
    printk(...);
    printk_symbol(addr);
    printk("\n");
    with a single non-interleavable in dmesg
    printk("... %pSR\n", (void *)addr);

    Update documentation too.

    Signed-off-by: Joe Perches <joe@perches.com>
    ---
    Documentation/printk-formats.txt | 2 ++
    lib/vsprintf.c | 18 +++++++++++++-----
    2 files changed, 15 insertions(+), 5 deletions(-)

    diff --git a/Documentation/printk-formats.txt b/Documentation/printk-formats.txt
    index 8ffb274..69a5ca1 100644
    --- a/Documentation/printk-formats.txt
    +++ b/Documentation/printk-formats.txt
    @@ -17,6 +17,8 @@ Symbols/Function Pointers:
    %pF versatile_init+0x0/0x110
    %pf versatile_init
    %pS versatile_init+0x0/0x110
    + %pSR versatile_init+0x9/0x110
    + (with __builtin_extract_return_addr() translation)
    %ps versatile_init
    %pB prev_fn_of_versatile_init+0x88/0x88

    diff --git a/lib/vsprintf.c b/lib/vsprintf.c
    index fab33a9..832ff0b 100644
    --- a/lib/vsprintf.c
    +++ b/lib/vsprintf.c
    @@ -534,14 +534,21 @@ char *string(char *buf, char *end, const char *s, struct printf_spec spec)

    static noinline_for_stack
    char *symbol_string(char *buf, char *end, void *ptr,
    - struct printf_spec spec, char ext)
    + struct printf_spec spec, const char *fmt)
    {
    - unsigned long value = (unsigned long) ptr;
    + unsigned long value;
    #ifdef CONFIG_KALLSYMS
    char sym[KSYM_SYMBOL_LEN];
    - if (ext == 'B')
    +#endif
    +
    + if (fmt[1] == 'R')
    + ptr = __builtin_extract_return_addr(ptr);
    + value = (unsigned long)ptr;
    +
    +#ifdef CONFIG_KALLSYMS
    + if (*fmt == 'B')
    sprint_backtrace(sym, value);
    - else if (ext != 'f' && ext != 's')
    + else if (*fmt != 'f' && *fmt != 's')
    sprint_symbol(sym, value);
    else
    sprint_symbol_no_offset(sym, value);
    @@ -987,6 +994,7 @@ int kptr_restrict __read_mostly;
    * - 'f' For simple symbolic function names without offset
    * - 'S' For symbolic direct pointers with offset
    * - 's' For symbolic direct pointers without offset
    + * - '[FfSs]R' as above with __builtin_extract_return_addr() translation
    * - 'B' For backtraced symbolic direct pointers with offset
    * - 'R' For decoded struct resource, e.g., [mem 0x0-0x1f 64bit pref]
    * - 'r' For raw struct resource, e.g., [mem 0x0-0x1f flags 0x201]
    @@ -1059,7 +1067,7 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr,
    case 'S':
    case 's':
    case 'B':
    - return symbol_string(buf, end, ptr, spec, *fmt);
    + return symbol_string(buf, end, ptr, spec, fmt);
    case 'R':
    case 'r':
    return resource_string(buf, end, ptr, spec, fmt);
    --
    1.7.8.112.g3fd21


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