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Diffstat (limited to 'libsframe/doc/sframe-spec.texi')
| -rw-r--r-- | libsframe/doc/sframe-spec.texi | 34 |
1 files changed, 28 insertions, 6 deletions
diff --git a/libsframe/doc/sframe-spec.texi b/libsframe/doc/sframe-spec.texi index ae11570..69fe873 100644 --- a/libsframe/doc/sframe-spec.texi +++ b/libsframe/doc/sframe-spec.texi @@ -21,6 +21,8 @@ License''. @titlepage @title The SFrame Format @subtitle Version 2 +@sp 15 +@center @today{} @author Indu Bhagat @page @@ -126,6 +128,17 @@ the data structure. @item The above two imply that each SFrame function descriptor entry has a fixed size of 20 bytes instead of its size of 17 bytes in SFrame format version 1. +@item +Add a new flag SFRAME_F_FDE_FUNC_START_PCREL, as an erratum to SFrame +Version 2, to indicate the encoding of the SFrame FDE function start address +field: + @itemize @minus + @item if set, @code{sfde_func_start_address} field contains the offset in +bytes to the start PC of the associated function from the field itself. + @item if unset, @code{sfde_func_start_address} field contains the offset in +bytes to the start PC of the associated function from the start of the SFrame +section. + @end itemize @end itemize SFrame version 1 is now obsolete and should not be used. @@ -232,21 +245,28 @@ describe various section-wide properties. The following flags are currently defined. -@multitable {@code{SFRAME_F_FRAME_POINTER}} {Versions} {Value} {Function Descriptor Entries} -@headitem Flag @tab Versions @tab Value @tab Meaning +@multitable {@code{SFRAME_F_FRAME_POINTER}} {Version} {Value} {Function Descriptor Entries are sorted} +@headitem Flag @tab Version @tab Value @tab Meaning @tindex SFRAME_F_FDE_SORTED @item @code{SFRAME_F_FDE_SORTED} @tab All @tab 0x1 @tab Function Descriptor Entries are sorted on PC. @tindex SFRAME_F_FRAME_POINTER @item @code{SFRAME_F_FRAME_POINTER} @tab All @tab 0x2 @tab All functions in the object file preserve frame pointer. +@tindex SFRAME_F_FDE_FUNC_START_PCREL +@item @code{SFRAME_F_FDE_FUNC_START_PCREL} @tab 2 @tab 0x4 +@tab The @code{sfde_func_start_address} field in the SFrame FDE is an offset in +bytes to the function's start address, from the field itself. If unset, the +@code{sfde_func_start_address} field in the SFrame FDE is an offset in bytes to +the function's start address, from the start of the SFrame section. @end multitable The purpose of SFRAME_F_FRAME_POINTER flag is to facilitate stack tracers to reliably fallback on the frame pointer based stack tracing method, if SFrame information is not present for some function in the SFrame section. -Further flags may be added in future. +Further flags may be added in future. Bits corresponding to the currently +undefined flags must be set to zero. @node SFrame Header @section SFrame Header @@ -459,9 +479,11 @@ Following table describes each component of the SFrame FDE structure: @tab @code{int32_t} @tab @code{sfde_func_start_address} @tab Signed 32-bit integral field denoting the virtual memory address of the -described function, for which the SFrame FDE applies. The value encoded in -the @code{sfde_func_start_address} field is the offset in bytes of the -function's start address, from the SFrame section. +described function, for which the SFrame FDE applies. If the flag +@code{SFRAME_F_FDE_FUNC_START_PCREL}, @xref{SFrame Flags}, in the SFrame +header is set, the value encoded in the @code{sfde_func_start_address} field is +the offset in bytes to the function's start address, from the SFrame +@code{sfde_func_start_address} field. @item 0x04 @tab @code{uint32_t} |